crdb_internal

On this page Carat arrow pointing down

The crdb_internal system catalog is a schema that contains information about internal objects, processes, and metrics related to a specific database. crdb_internal tables are read-only.

Tables

Warning:

Do not use the crdb_internal tables marked with ✗ in production environments for the following reasons:

  • The contents of these tables are unstable, and subject to change in new releases of CockroachDB, without prior notice.
  • There are memory and latency costs associated with each table in crdb_internal. Accessing the tables in the schema can impact cluster stability and performance.

To view the schema and query examples for a table supported in production, click the table name.

Table name Description Use in production
active_range_feeds Contains information about range feeds on nodes in your cluster.
backward_dependencies Contains information about backward dependencies.
builtin_functions Contains information about supported functions.
cluster_contended_indexes Contains information about contended indexes in your cluster.
cluster_contended_keys Contains information about contended keys in your cluster.
cluster_contended_tables Contains information about contended tables in your cluster.
cluster_contention_events Contains information about contention in your cluster.
cluster_locks Contains information about locks held by transactions on specific keys.
cluster_database_privileges Contains information about the database privileges on your cluster.
cluster_execution_insights Contains information about SQL statement executions on your cluster.
cluster_distsql_flows Contains information about the flows of the DistSQL execution scheduled in your cluster.
cluster_inflight_traces Contains information about in-flight tracing in your cluster.
cluster_queries Contains information about queries running on your cluster.
cluster_sessions Contains information about cluster sessions, including current and past queries.
cluster_settings Contains information about cluster settings.
cluster_transactions Contains information about transactions running on your cluster.
create_statements Contains information about tables and indexes in your database.
create_function_statements Contains information about user-defined functions in your database.
create_type_statements Contains information about user-defined types in your database.
cross_db_references Contains information about objects that reference other objects, such as foreign keys or views, across databases in your cluster.
databases Contains information about the databases in your cluster.
default_privileges Contains information about per-database default privileges.
feature_usage Contains information about feature usage on your cluster.
forward_dependencies Contains information about forward dependencies.
gossip_alerts Contains information about gossip alerts.
gossip_liveness Contains information about your cluster's gossip liveness.
gossip_network Contains information about your cluster's gossip network.
gossip_nodes Contains information about nodes in your cluster's gossip network.
index_columns Contains information about indexed columns in your cluster.
index_usage_statistics Contains statistics about the primary and secondary indexes used in statements.
invalid_objects Contains information about invalid objects in your cluster.
jobs Contains information about jobs running on your cluster.
kv_node_liveness Contains information about node liveness.
kv_node_status Contains information about node status at the key-value layer.
kv_store_status Contains information about the key-value store for your cluster.
leases Contains information about leases in your cluster.
lost_descriptors_with_data Contains information about table descriptors that have been deleted but still have data left over in storage.
node_build_info Contains information about nodes in your cluster.
node_contention_events Contains information about contention on the gateway node of your cluster.
node_execution_insights Contains information about SQL statement executions on the gateway node of your cluster.
node_distsql_flows Contains information about the flows of the DistSQL execution scheduled on nodes in your cluster.
node_inflight_trace_spans Contains information about currently in-flight spans in the current node.
node_metrics Contains metrics for nodes in your cluster.
node_queries Contains information about queries running on nodes in your cluster.
node_runtime_info Contains runtime information about nodes in your cluster.
node_sessions Contains information about sessions to nodes in your cluster.
node_statement_statistics Contains statement statistics for nodes in your cluster.
node_transaction_statistics Contains transaction statistics for nodes in your cluster.
node_transactions Contains information about transactions for nodes in your cluster.
node_txn_stats Contains transaction statistics for nodes in your cluster.
partitions Contains information about partitions in your cluster.
predefined_comments Contains predefined comments about your cluster.
ranges Contains information about ranges in your cluster.
ranges_no_leases Contains information about ranges in your cluster, without leases.
regions Contains information about cluster regions.
schema_changes Contains information about schema changes in your cluster.
session_trace Contains session trace information for your cluster.
session_variables Contains information about session variables in your cluster.
statement_statistics Aggregates in-memory and persisted statistics from system.statement_statistics within hourly time intervals based on UTC time, rounded down to the nearest hour. To reset the statistics call SELECT crdb_internal.reset_sql_stats().
table_columns Contains information about table columns in your cluster.
table_indexes Contains information about table indexes in your cluster.
table_row_statistics Contains row count statistics for tables in the current database.
tables Contains information about tables in your cluster.
transaction_contention_events Contains information about historical transaction contention events.
transaction_statistics Aggregates in-memory and persisted statistics from system.transaction_statistics within hourly time intervals based on UTC time, rounded down to the nearest hour. To reset the statistics, call SELECT crdb_internal.reset_sql_stats().
zones Contains information about zone configurations in your cluster.

List crdb_internal tables

To list the crdb_internal tables for the current database, use the following SHOW TABLES statement:

icon/buttons/copy
> SHOW TABLES FROM crdb_internal;
   schema_name  |         table_name              | type  | owner | estimated_row_count | locality
----------------+---------------------------------+-------+-------+---------------------+-----------
  crdb_internal | active_range_feeds              | table | NULL  |                NULL | NULL
  crdb_internal | backward_dependencies           | table | NULL  |                NULL | NULL
  crdb_internal | builtin_functions               | table | NULL  |                NULL | NULL
  crdb_internal | cluster_contended_indexes       | view  | NULL  |                NULL | NULL
  crdb_internal | cluster_contended_keys          | view  | NULL  |                NULL | NULL
  crdb_internal | cluster_contended_tables        | view  | NULL  |                NULL | NULL
  crdb_internal | cluster_contention_events       | table | NULL  |                NULL | NULL
  crdb_internal | cluster_database_privileges     | table | NULL  |                NULL | NULL
  crdb_internal | cluster_distsql_flows           | table | NULL  |                NULL | NULL
  crdb_internal | cluster_inflight_traces         | table | NULL  |                NULL | NULL
  ...

Query crdb_internal tables

To get detailed information about objects, processes, or metrics related to your database, you can read from the crdb_internal table that corresponds to the item of interest.

Tip:
  • To ensure that you can view all of the tables in crdb_internal, query the tables as a user with the admin role.
  • Unless specified otherwise, queries to crdb_internal assume the current database.

For example, to return the crdb_internal table for the index usage statistics of the movr database, you can use the following statement:

icon/buttons/copy
> SELECT * FROM movr.crdb_internal.index_usage_statistics;
  table_id | index_id | total_reads |           last_read
-----------+----------+-------------+--------------------------------
        53 |        1 |       36792 | 2021-12-02 22:35:39.270713+00
        54 |        1 |       24527 | 2021-12-02 22:35:39.053428+00
        54 |        2 |      582120 | 2021-12-02 22:35:39.985883+00
        55 |        1 |      309194 | 2021-12-02 22:35:39.619138+00
        55 |        2 |           1 | 2021-12-02 00:28:26.176012+00
        55 |        3 |           1 | 2021-12-02 00:28:31.122689+00
        56 |        1 |           1 | 2021-12-02 00:28:32.074418+00
        57 |        1 |        6116 | 2021-12-02 22:34:50.446242+00
        58 |        1 |        3059 | 2021-12-02 22:34:50.447769+00

Table schema

This section provides the schema and examples for tables supported in production.

cluster_contended_indexes

Column Type Description
database_name STRING The name of the database experiencing contention.
schema_name STRING The name of the schema experiencing contention.
table_name STRING The name of the table experiencing contention.
index_name STRING The name of the index experiencing contention.
num_contention_events INT8 The number of contention events.

View all indexes that have experienced contention

icon/buttons/copy
SELECT * FROM movr.crdb_internal.cluster_contended_indexes;

  database_name | schema_name | table_name |              index_name               | num_contention_events
----------------+-------------+------------+---------------------------------------+------------------------
  movr          | public      | vehicles   | vehicles_auto_index_fk_city_ref_users |                     2

cluster_contended_keys

Column Type Description
database_name STRING The name of the database experiencing contention.
schema_name STRING The name of the schema experiencing contention.
table_name STRING The name of the table experiencing contention.
index_name STRING The name of the index experiencing contention.
key BYTES The key experiencing contention.
num_contention_events INT8 The number of contention events.

View all keys that have experienced contention

icon/buttons/copy
SELECT table_name, index_name, key, num_contention_events FROM movr.crdb_internal.cluster_contended_keys where database_name = 'movr';
  table_name |              index_name               |                                                             key                                                             | num_contention_events
-------------+---------------------------------------+-----------------------------------------------------------------------------------------------------------------------------+------------------------
  vehicles   | vehicles_auto_index_fk_city_ref_users | /107/2/"amsterdam"/"\xe2\xc2\xdcJ$\xf3A\xa2\x98\xad.\xe6<Y\x05\xef"/"\x98\x05\xe1B\x82sE\x13\xba\xfe+,k\xd3\xc6\xd3"/0      |                     1
  vehicles   | vehicles_auto_index_fk_city_ref_users | /107/2/"seattle"/"v\xd4J%\x90\x1bF\v\x97\x02v\xc7\xee\xa9\xc7R"/"s\xa1\xad\x8c\xca\xe4G\t\xadG\x91\xa3\xa4\xae\xb7\xc7"/0   |                     1
  vehicles   | vehicles_auto_index_fk_city_ref_users | /107/2/"seattle"/"7\xfe\x953~\x94F\x95\xacàP\x8e_A\x18"/"\xccέ\xa0\xcaoAژ\x81\xab\xe9\xb6'ɐ"/0                              |                     1
  vehicles   | vehicles_auto_index_fk_city_ref_users | /107/2/"rome"/"oAņ\xd8\xcdE\xfb\xb6\xb7\x8e9\xb4\xae\xc1,"/"ڲ@\x1f\x1d\x05LɌ\xba\xb9\x97\x84\x9e\x98\x1d"/0                 |                     1
  vehicles   | vehicles_auto_index_fk_city_ref_users | /107/2/"paris"/"^\xefĦ\xed\vFI\x89\xe7\xfe\xbd\x8em\xe0\xb8"/"F%\xffZ\xe8\x93N\xfc\xa6\x17\xc0S\xb6\x86\xdd\xec"/0          |                     1
  vehicles   | vehicles_auto_index_fk_city_ref_users | /107/2/"new york"/"\xfd\x81\xc0UK\x9cEE\xa7\x14b\xdb\x02\xad\x80\xe8"/"a\xc0q\x82\x8e)@\x89\xa2\x9c\xcc\xdb\x01\x1d\x8e_"/0 |                     1
  vehicles   | vehicles_auto_index_fk_city_ref_users | /107/2/"new york"/"\xe9\xf9<\x99\\\x18K\xa2\x8d\xd2a\xa1d\x937\n"/"ͮ\x18\xd4\xe9\xb3A\xf3\xb5\x9c\x177\x8c\xf6\x0e\xc5"/0    |                     1
  vehicles   | vehicles_auto_index_fk_city_ref_users | /107/2/"new york"/"\x0f\x05\x9b\x1a[\xda@\x13\x83v\xfb\x8b\xdf4\"\xbd"/"N\xe0>\x1e\xf4gLݷ95\xfc0\x95\xea["/0                |                     1
  vehicles   | vehicles_auto_index_fk_city_ref_users | /107/2/"los angeles"/"h\xc8\xfa\xc5J\xf8A7\xbe\x98\xa3\x94\x8e\xf4\x991"/",\u007fh)\"\x92G̞\xde\xeb\x973\xdfK\xb4"/0         |                     1
  vehicles   | rides_auto_index_fk_city_ref_users    | /107/2/"amsterdam"/"\xe2\xc2\xdcJ$\xf3A\xa2\x98\xad.\xe6<Y\x05\xef"/"\x98\x05\xe1B\x82sE\x13\xba\xfe+,k\xd3\xc6\xd3"/0      |                     1
  vehicles   | rides_auto_index_fk_city_ref_users    | /107/2/"seattle"/"v\xd4J%\x90\x1bF\v\x97\x02v\xc7\xee\xa9\xc7R"/"s\xa1\xad\x8c\xca\xe4G\t\xadG\x91\xa3\xa4\xae\xb7\xc7"/0   |                     1
  vehicles   | rides_auto_index_fk_city_ref_users    | /107/2/"seattle"/"7\xfe\x953~\x94F\x95\xacàP\x8e_A\x18"/"\xccέ\xa0\xcaoAژ\x81\xab\xe9\xb6'ɐ"/0                              |                     1
  vehicles   | rides_auto_index_fk_city_ref_users    | /107/2/"rome"/"oAņ\xd8\xcdE\xfb\xb6\xb7\x8e9\xb4\xae\xc1,"/"ڲ@\x1f\x1d\x05LɌ\xba\xb9\x97\x84\x9e\x98\x1d"/0                 |                     1
  vehicles   | rides_auto_index_fk_city_ref_users    | /107/2/"paris"/"^\xefĦ\xed\vFI\x89\xe7\xfe\xbd\x8em\xe0\xb8"/"F%\xffZ\xe8\x93N\xfc\xa6\x17\xc0S\xb6\x86\xdd\xec"/0          |                     1
  vehicles   | rides_auto_index_fk_city_ref_users    | /107/2/"new york"/"\xfd\x81\xc0UK\x9cEE\xa7\x14b\xdb\x02\xad\x80\xe8"/"a\xc0q\x82\x8e)@\x89\xa2\x9c\xcc\xdb\x01\x1d\x8e_"/0 |                     1
  vehicles   | rides_auto_index_fk_city_ref_users    | /107/2/"new york"/"\xe9\xf9<\x99\\\x18K\xa2\x8d\xd2a\xa1d\x937\n"/"ͮ\x18\xd4\xe9\xb3A\xf3\xb5\x9c\x177\x8c\xf6\x0e\xc5"/0    |                     1
  vehicles   | rides_auto_index_fk_city_ref_users    | /107/2/"new york"/"\x0f\x05\x9b\x1a[\xda@\x13\x83v\xfb\x8b\xdf4\"\xbd"/"N\xe0>\x1e\xf4gLݷ95\xfc0\x95\xea["/0                |                     1
  vehicles   | rides_auto_index_fk_city_ref_users    | /107/2/"los angeles"/"h\xc8\xfa\xc5J\xf8A7\xbe\x98\xa3\x94\x8e\xf4\x991"/",\u007fh)\"\x92G̞\xde\xeb\x973\xdfK\xb4"/0         |                     1
(18 rows)             6

cluster_contended_tables

Column Type Description
database_name STRING The name of the database experiencing contention.
schema_name STRING The name of the schema experiencing contention.
table_name STRING The name of the table experiencing contention.
num_contention_events INT8 The number of contention events.

View all tables that have experienced contention

icon/buttons/copy
> SELECT * FROM movr.crdb_internal.cluster_contended_tables;
  database_name | schema_name | table_name | num_contention_events
----------------+-------------+------------+------------------------
  movr          | public      | vehicles   |                     9
(1 row)

cluster_contention_events

Column Type Description
table_id INT8 Unique table identifier.
index_id INT8 Unique index identifier.
num_contention_events INT8 The number of contention events.
cumulative_contention_time INTERVAL The cumulative time that the transaction spends waiting in contention.
key BYTES The key experiencing contention.
txn_id UUID Unique transaction identifier.
count INT8 The number of contention events.

View all contention events

icon/buttons/copy
SELECT * FROM crdb_internal.cluster_contention_events;
  table_id | index_id | num_contention_events | cumulative_contention_time |                                                                               key                                                                               |                txn_id                | count
-----------+----------+-----------------------+----------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------+--------------------------------------+--------
       107 |        2 |                     9 | 00:00:00.039563            | \xf3\x8a\x12amsterdam\x00\x01\x12\xe2\xc2\xdcJ$\xf3A\xa2\x98\xad.\xe6<Y\x05\xef\x00\x01\x12\x98\x05\xe1B\x82sE\x13\xba\xfe+,k\xd3\xc6\xd3\x00\x01\x88           | 2701fe08-44bf-44ca-a2f7-6d2c9b652f9f |     1
       107 |        2 |                     9 | 00:00:00.039563            | \xf3\x8a\x12los angeles\x00\x01\x12h\xc8\xfa\xc5J\xf8A7\xbe\x98\xa3\x94\x8e\xf4\x991\x00\x01\x12,\x7fh)"\x92G\xcc\x9e\xde\xeb\x973\xdfK\xb4\x00\x01\x88         | 2595e2d5-84b1-47a6-acc3-e6fdab47da41 |     1
       107 |        2 |                     9 | 00:00:00.039563            | \xf3\x8a\x12new york\x00\x01\x12\x0f\x05\x9b\x1a[\xda@\x13\x83v\xfb\x8b\xdf4"\xbd\x00\x01\x12N\xe0>\x1e\xf4gL\xdd\xb795\xfc0\x95\xea[\x00\x01\x88               | 58b59e88-87b8-45eb-bc9b-34e6a6b53a2c |     1
       107 |        2 |                     9 | 00:00:00.039563            | \xf3\x8a\x12new york\x00\x01\x12\xe9\xf9<\x99\\\x18K\xa2\x8d\xd2a\xa1d\x937\n\x00\x01\x12\xcd\xae\x18\xd4\xe9\xb3A\xf3\xb5\x9c\x177\x8c\xf6\x0e\xc5\x00\x01\x88 | 9af8a934-7ffa-4715-b802-f532f15bea9c |     1
       107 |        2 |                     9 | 00:00:00.039563            | \xf3\x8a\x12new york\x00\x01\x12\xfd\x81\xc0UK\x9cEE\xa7\x14b\xdb\x02\xad\x80\xe8\x00\x01\x12a\xc0q\x82\x8e)@\x89\xa2\x9c\xcc\xdb\x01\x1d\x8e_\x00\x01\x88      | af7ee3f2-23b8-46ef-bef7-a11b1be73443 |     1
       107 |        2 |                     9 | 00:00:00.039563            | \xf3\x8a\x12paris\x00\x01\x12^\xef\xc4\xa6\xed\x0bFI\x89\xe7\xfe\xbd\x8em\xe0\xb8\x00\x01\x12F%\xffZ\xe8\x93N\xfc\xa6\x17\xc0S\xb6\x86\xdd\xec\x00\x01\x88      | 594bec92-af85-4a8d-bb4d-cc17d5bbd905 |     1
       107 |        2 |                     9 | 00:00:00.039563            | \xf3\x8a\x12rome\x00\x01\x12oA\xc5\x86\xd8\xcdE\xfb\xb6\xb7\x8e9\xb4\xae\xc1,\x00\x01\x12\xda\xb2@\x1f\x1d\x05L\xc9\x8c\xba\xb9\x97\x84\x9e\x98\x1d\x00\x01\x88 | 815dcf03-7a0a-4c3a-98df-be7d84c1fd13 |     1
       107 |        2 |                     9 | 00:00:00.039563            | \xf3\x8a\x12seattle\x00\x01\x127\xfe\x953~\x94F\x95\xac\xc3\xa0P\x8e_A\x18\x00\x01\x12\xcc\xce\xad\xa0\xcaoA\xda\x98\x81\xab\xe9\xb6\'\xc9\x90\x00\x01\x88      | 5d382859-e88d-497a-830b-613fd20ef304 |     1
       107 |        2 |                     9 | 00:00:00.039563            | \xf3\x8a\x12seattle\x00\x01\x12v\xd4J%\x90\x1bF\x0b\x97\x02v\xc7\xee\xa9\xc7R\x00\x01\x12s\xa1\xad\x8c\xca\xe4G\t\xadG\x91\xa3\xa4\xae\xb7\xc7\x00\x01\x88      | e83df970-a01a-470f-914d-f5615eeec620 |     1
(9 rows)

View the tables/indexes with the most time under contention

To view the tables and indexes with the most cumulative time under contention since the last server restart, run the query below.

Note:

The default tracing behavior captures a small percent of transactions so not all contention events will be recorded. When investigating transaction contention, you can set the sql.trace.txn.enable_threshold cluster setting to always capture contention events.

icon/buttons/copy
WITH c AS (SELECT DISTINCT ON (table_id, index_id) table_id, index_id, num_contention_events AS events, cumulative_contention_time AS time FROM crdb_internal.cluster_contention_events) SELECT i.descriptor_name, i.index_name, c.events, c.time FROM crdb_internal.table_indexes AS i JOIN c ON i.descriptor_id = c.table_id AND i.index_id = c.index_id ORDER BY c.time DESC LIMIT 10;
  descriptor_name |   index_name   | events |      time
------------------+----------------+--------+------------------
  warehouse       | warehouse_pkey |      7 | 00:00:01.046293
  district        | district_pkey  |      1 | 00:00:00.191346
  stock           | stock_pkey     |      1 | 00:00:00.158207
  order           | order_pkey     |      1 | 00:00:00.155404
  new_order       | new_order_pkey |      1 | 00:00:00.100949
(5 rows)

(The output above is for a local cluster running the TPC-C workload at a --concurrency of 256.)

cluster_locks

The crdb_internal.cluster_locks schema contains information about locks held by transactions on specific keys. Queries acquire locks on keys within transactions, or they wait until they can acquire locks until other transactions have released locks on those keys.

For more information, see the following sections.

Cluster locks columns

The crdb_internal.cluster_locks table has the following columns that describe each lock:

Column Type Description
range_id INT The ID of the range that stores the key the lock is being acquired on.
table_id INT The ID of the table that includes the key the lock is being acquired on.
database_name STRING The name of the database that includes the key the lock is being acquired on.
schema_name STRING The name of the schema that includes the key this lock is being acquired on.
table_name STRING The name of the table that includes the key this lock is being acquired on.
index_name STRING The name of the index that includes the key this lock is being acquired on.
lock_key BYTES The actual key that this lock is being acquired on.
lock_key_pretty STRING A string representation of the key this lock is being acquired on.
txn_id UUID The ID of the transaction that is acquiring this lock.
ts TIMESTAMP The timestamp at which this lock was acquired.
lock_strength STRING The strength of this lock. Allowed values: "Exclusive" or "None" (read-only requests don't need an exclusive lock).
durability STRING Whether the lock is one of: Replicated or Unreplicated. For more information about lock replication, see types of locking.
granted BOOLEAN Whether this lock has been granted to the transaction requesting it.
contended BOOLEAN Whether multiple transactions are trying to acquire a lock on this key.
duration INTERVAL The length of time this lock has been held for.
Tip:

You can see the types and default values of columns in this and other tables using SHOW COLUMNS FROM {table}.

Cluster locks - basic example

In this example, we'll use the SELECT FOR UPDATE statement to order two transactions by controlling concurrent access to a table. Then, we will look at the data in cluster_locks to see the locks being held by these transactions on the objects they are accessing.

This example assumes you are running a local unsecured cluster.

First, connect to the running cluster (call this Terminal 1):

icon/buttons/copy
cockroach sql --insecure

Next, create a table and insert some rows:

icon/buttons/copy
CREATE TABLE kv (k INT PRIMARY KEY, v INT);
INSERT INTO kv (k, v) VALUES (1, 5), (2, 10), (3, 15);

Next, we'll start a transaction and lock the row we want to operate on:

icon/buttons/copy
BEGIN;
SELECT * FROM kv WHERE k = 1 FOR UPDATE;

Press Enter twice in the SQL client to send the statements to be evaluated. This will result in the following output:

  k | v
+---+----+
  1 | 5
(1 row)

Now open another terminal and connect to the database from a second client (call this Terminal 2):

icon/buttons/copy
cockroach sql --insecure

From Terminal 2, start a transaction and try to lock the same row for updates that is already being accessed by the transaction we opened in Terminal 1:

icon/buttons/copy
BEGIN;
SELECT * FROM kv WHERE k = 1 FOR UPDATE;

Press Enter twice to send the statements to be evaluated. Because Terminal 1 has already locked this row, the SELECT FOR UPDATE statement from Terminal 2 will appear to "wait".

Now that we have two transactions both trying to update the kv table, let's query the data in crdb_internal.cluster_locks. We should see two locks:

icon/buttons/copy
SELECT database_name, table_name, txn_id, ts, lock_key_pretty, lock_strength, granted, contended FROM crdb_internal.cluster_locks WHERE table_name = 'kv';
  database_name | table_name |                txn_id                |             ts             | lock_key_pretty  | lock_strength | granted | contended
----------------+------------+--------------------------------------+----------------------------+------------------+---------------+---------+------------
  defaultdb     | kv         | d11a08c4-a3a2-4bdb-bf10-8d2373426faf | 2022-07-27 18:57:06.808046 | /Table/107/1/1/0 | Exclusive     |  true   |   true
  defaultdb     | kv         | 34ebadb6-99f1-4547-b487-4b322506b7fe | 2022-07-27 18:57:13.173556 | /Table/107/1/1/0 | Exclusive     |  false  |   true
(2 rows)

As expected, there are two locks. This is the case because:

  • The transaction with the SELECT FOR UPDATE query in Terminal 1 asked for an Exclusive lock on a row in the defaultdb.kv table, as shown in the lock_strength column. We can see that it was able to get that lock, since the granted column is true.
  • The transaction in Terminal 2 is also trying to lock the same row in the kv table with a lock_strength of Exclusive. However, the value of the granted column is false, which means it could not get the exclusive lock yet, and is waiting on the lock from the query in Terminal 1 to be released before it can proceed.

Further, both transactions show the contended column as true, since these transactions are both trying to update rows in the defaultdb.kv table at the same time.

The following more complex query shows additional information about lockholders, sessions, and waiting queries. This may be useful on a busy cluster for figuring out which transactions from which clients are trying to grab locks. Note that joining with cluster_queries will only show queries currently in progress.

icon/buttons/copy
SELECT
    sessions.session_id,
    sessions.client_address,
    sessions.application_name,
    locks.txn_id,
    queries.query_id AS waiting_query_id,
    queries.query AS waiting_query,
    locks.lock_key_pretty,
    locks.ts,
    locks.database_name,
    locks.schema_name,
    locks.table_name,
    locks.lock_strength,
    locks.granted,
    locks.contended
FROM
    crdb_internal.cluster_locks AS locks
    JOIN crdb_internal.cluster_sessions AS sessions ON
            locks.txn_id::STRING = sessions.kv_txn
    LEFT JOIN crdb_internal.cluster_queries AS queries ON
            locks.txn_id = queries.txn_id
              session_id            | client_address  | application_name |                txn_id                |         waiting_query_id         |              waiting_query              | lock_key_pretty  |             ts             | database_name | schema_name | table_name | lock_strength | granted | contended
-----------------------------------+-----------------+------------------+--------------------------------------+----------------------------------+-----------------------------------------+------------------+----------------------------+---------------+-------------+------------+---------------+---------+------------
  17056bb535ead9a00000000000000001 | 127.0.0.1:51093 | $ cockroach sql  | ca692f0a-deca-4d4a-9a15-86f25c3b837f | NULL                             | NULL                                    | /Table/107/1/1/0 | 2022-07-26 15:48:08.294631 | defaultdb     | public      | kv         | Exclusive     |  true   |   true
  17056bb7e47a6ec00000000000000003 | 127.0.0.1:51094 | $ cockroach sql  | 771fe98f-9e39-4ce4-90da-8ecb06d2a856 | 17056bbd362852780000000000000003 | SELECT * FROM kv WHERE k = 1 FOR UPDATE | /Table/107/1/1/0 | 2022-07-26 15:48:18.145594 | defaultdb     | public      | kv         | Exclusive     |  false  |   true
(2 rows)

The output is similar to querying cluster_locks alone, except you can see the text of the SQL queries whose transactions are waiting on other transactions to finish, with additional information about the clients that initiated those transactions.

Note:

Locks are held by transactions, not queries. A lock can be acquired by a transaction as a result of a query, but CockroachDB does not track which query in a transaction caused that transaction to acquire a lock.

Cluster locks - intermediate example

This example assumes you have a cluster in the state it was left in by the previous example.

In this example you will run a workload on the cluster with multiple concurrent transactions using the bank workload. With a sufficiently high concurrency setting, the bank workload will frequently attempt to update multiple accounts at the same time. This will create plenty of locks to view in the crdb_internal.cluster_locks table.

  1. Initialize the workload:

    icon/buttons/copy
    cockroach workload init bank 'postgresql://root@localhost:26257/bank?sslmode=disable'
    
  2. Run it at a high concurrency setting:

    icon/buttons/copy
    cockroach workload run bank --concurrency=128 --duration=3m 'postgresql://root@localhost:26257/bank?sslmode=disable'
    
  3. While the workload is running, issue the following query to view a subset of the locks being requested:

    icon/buttons/copy
    SELECT
        database_name,
        table_name,
        txn_id,
        ts,
        lock_key_pretty,
        lock_strength,
        granted,
        contended
    FROM
        crdb_internal.cluster_locks
    WHERE table_name = 'bank'
    LIMIT
        10
    
      database_name | table_name |                txn_id                |             ts             |  lock_key_pretty   | lock_strength | granted | contended
    ----------------+------------+--------------------------------------+----------------------------+--------------------+---------------+---------+------------
      bank          | bank       | 7f0e262f-78e6-4a52-ad4e-d3cd5a851c82 | 2022-07-27 18:59:09.358877 | /Table/110/1/82/0  | Exclusive     |  true   |   false
      bank          | bank       | c5bdc305-5940-43e1-8017-95260b4a1a39 | 2022-07-27 18:59:06.071559 | /Table/110/1/110/0 | Exclusive     |  true   |   true
      bank          | bank       | ec872809-06b6-4320-b416-88b37c656f28 | 2022-07-27 18:59:05.843786 | /Table/110/1/110/0 | Exclusive     |  false  |   true
      bank          | bank       | 7f4cd00d-2765-4b8d-b2e3-96e1c20e515e | 2022-07-27 18:59:06.345931 | /Table/110/1/110/0 | Exclusive     |  false  |   true
      bank          | bank       | d6683639-a529-43b1-89ce-e7f0aa268426 | 2022-07-27 18:59:06.800857 | /Table/110/1/110/0 | Exclusive     |  false  |   true
      bank          | bank       | ffbeb239-9fba-4cd8-8f20-ccebe3a069cd | 2022-07-27 18:59:07.485126 | /Table/110/1/110/0 | Exclusive     |  false  |   true
      bank          | bank       | 7f64b1f5-e70e-4257-9d5b-5a26e48001cf | 2022-07-27 18:59:07.77492  | /Table/110/1/110/0 | Exclusive     |  false  |   true
      bank          | bank       | 3e4ca7d5-77ef-474b-8ffa-4eeeffa0d190 | 2022-07-27 18:59:08.888788 | /Table/110/1/110/0 | Exclusive     |  false  |   true
      bank          | bank       | 57d984d7-54a9-4c7f-893d-a8c67e748bbe | 2022-07-27 18:59:05.117683 | /Table/110/1/110/0 | Exclusive     |  false  |   true
      bank          | bank       | 3c06319f-31c3-43ba-8323-9807e2c6de04 | 2022-07-27 18:59:05.117683 | /Table/110/1/110/0 | Exclusive     |  false  |   true
    (10 rows)
    

As in the basic example, you can see that some transactions that wanted locks on the bank table are having to wait (granted is false), usually because they are trying to operate on the same rows as one or more other transactions (contended is true).

The following more complex query shows additional information about lockholders, sessions, and waiting queries. This may be useful on a busy cluster for figuring out which transactions from which clients are trying to grab locks. Note that joining with cluster_queries will only show queries currently in progress.

icon/buttons/copy
SELECT
    sessions.session_id,
    sessions.client_address,
    sessions.application_name,
    locks.txn_id,
    queries.query_id AS waiting_query_id,
    queries.query AS waiting_query,
    locks.lock_key_pretty,
    locks.ts,
    locks.database_name,
    locks.schema_name,
    locks.table_name,
    locks.lock_strength,
    locks.granted,
    locks.contended
FROM
    crdb_internal.cluster_locks AS locks
    JOIN crdb_internal.cluster_sessions AS sessions ON
            locks.txn_id::STRING = sessions.kv_txn
    LEFT JOIN crdb_internal.cluster_queries AS queries ON
            locks.txn_id = queries.txn_id
WHERE
    locks.table_name = 'bank'
LIMIT
    10
             session_id            | client_address  | application_name |                txn_id                |         waiting_query_id         |                                                    waiting_query                                                     |  lock_key_pretty   |             ts             | database_name | schema_name | table_name | lock_strength | granted | contended
-----------------------------------+-----------------+------------------+--------------------------------------+----------------------------------+----------------------------------------------------------------------------------------------------------------------+--------------------+----------------------------+---------------+-------------+------------+---------------+---------+------------
  17056cb7396db5900000000000000001 | 127.0.0.1:51220 | bank             | 3bee08fd-636e-4d41-b28d-104bd0a4235b | 17056cded0850d800000000000000001 | UPDATE bank SET balance = CASE id WHEN 351 THEN balance - 725 WHEN 412 THEN balance + 725 END WHERE id IN (351, 412) | /Table/110/1/351/0 | 2022-07-26 16:09:31.215922 | bank          | public      | bank       | Exclusive     |  false  |   true
  17056cb7396db5900000000000000001 | 127.0.0.1:51220 | bank             | 3bee08fd-636e-4d41-b28d-104bd0a4235b | 17056cded0850d800000000000000001 | UPDATE bank SET balance = CASE id WHEN 351 THEN balance - 725 WHEN 412 THEN balance + 725 END WHERE id IN (351, 412) | /Table/110/1/412/0 | 2022-07-26 16:09:31.215922 | bank          | public      | bank       | Exclusive     |  false  |   true
  17056cb73972ab180000000000000001 | 127.0.0.1:51221 | bank             | 5c27678d-3acb-4d9d-8b98-774c5a10f933 | 17056ce6f3db1d080000000000000001 | UPDATE bank SET balance = CASE id WHEN 627 THEN balance - 794 WHEN 867 THEN balance + 794 END WHERE id IN (627, 867) | /Table/110/1/627/0 | 2022-07-26 16:09:36.945352 | bank          | public      | bank       | Exclusive     |  true   |   false
  17056cb73972ab180000000000000001 | 127.0.0.1:51221 | bank             | 5c27678d-3acb-4d9d-8b98-774c5a10f933 | 17056ce6f3db1d080000000000000001 | UPDATE bank SET balance = CASE id WHEN 627 THEN balance - 794 WHEN 867 THEN balance + 794 END WHERE id IN (627, 867) | /Table/110/1/867/0 | 2022-07-26 16:09:36.945352 | bank          | public      | bank       | Exclusive     |  true   |   false
  17056cb739738da80000000000000001 | 127.0.0.1:51222 | bank             | 1768cc1d-0929-490b-86bd-f39b9f78cc84 | 17056cdc278d47580000000000000001 | UPDATE bank SET balance = CASE id WHEN 351 THEN balance - 412 WHEN 412 THEN balance + 412 END WHERE id IN (351, 412) | /Table/110/1/351/0 | 2022-07-26 16:09:31.215922 | bank          | public      | bank       | Exclusive     |  false  |   true
  17056cb739738da80000000000000001 | 127.0.0.1:51222 | bank             | 1768cc1d-0929-490b-86bd-f39b9f78cc84 | 17056cdc278d47580000000000000001 | UPDATE bank SET balance = CASE id WHEN 351 THEN balance - 412 WHEN 412 THEN balance + 412 END WHERE id IN (351, 412) | /Table/110/1/412/0 | 2022-07-26 16:09:31.215922 | bank          | public      | bank       | Exclusive     |  false  |   true
  17056cb739737e080000000000000001 | 127.0.0.1:51223 | bank             | bf6ab816-67b7-4125-bf88-3d5c36986885 | 17056ce55b0065580000000000000001 | UPDATE bank SET balance = CASE id WHEN 137 THEN balance - 500 WHEN 895 THEN balance + 500 END WHERE id IN (137, 895) | /Table/110/1/137/0 | 2022-07-26 16:09:25.957139 | bank          | public      | bank       | Exclusive     |  false  |   true
  17056cb739772b700000000000000001 | 127.0.0.1:51226 | bank             | a9cff324-00bd-4e33-afc6-ff3341988c7e | 17056cd1cb394ab00000000000000001 | UPDATE bank SET balance = CASE id WHEN 498 THEN balance - 584 WHEN 690 THEN balance + 584 END WHERE id IN (498, 690) | /Table/110/1/690/0 | 2022-07-26 16:09:30.318277 | bank          | public      | bank       | Exclusive     |  false  |   true
  17056cb7397b03d00000000000000001 | 127.0.0.1:51225 | bank             | 5a591e0d-ba25-424f-aa13-502a7044355b | 17056cdb5243ea200000000000000001 | UPDATE bank SET balance = CASE id WHEN 110 THEN balance - 641 WHEN 895 THEN balance + 641 END WHERE id IN (110, 895) | /Table/110/1/110/0 | 2022-07-26 16:09:02.283466 | bank          | public      | bank       | Exclusive     |  false  |   true
  17056cb7397bdaa80000000000000001 | 127.0.0.1:51227 | bank             | 40a7f865-c6a6-40e2-8956-01f3f52b19f2 | 17056ccea1c21de00000000000000001 | UPDATE bank SET balance = CASE id WHEN 895 THEN balance - 506 WHEN 786 THEN balance + 506 END WHERE id IN (895, 786) | /Table/110/1/786/0 | 2022-07-26 16:08:19.842191 | bank          | public      | bank       | Exclusive     |  false  |   true
(10 rows)

The output is similar to querying cluster_locks alone, except you can see the text of the SQL queries whose transactions are waiting on other transactions to finish, with additional information about the clients that initiated those transactions.

Note:

Locks are held by transactions, not queries. A lock can be acquired by a transaction as a result of a query within that transaction, but CockroachDB does not track which query in a transaction caused that transaction to acquire a lock.

Blocked vs. blocking transactions

Run the query below to display a list of pairs of transactions that are holding and waiting on locks for the same keys.

This example assumes you are running the bank workload as described in the intermediate example.

icon/buttons/copy
SELECT
    lh.database_name,
    lh.table_name,
    lh.range_id,
    lh.lock_key_pretty,
    lh.txn_id AS lock_holder,
    lw.txn_id AS lock_waiter,
    q.query AS waiting_query,
    lw.duration AS wait_duration
FROM
    crdb_internal.cluster_locks AS lh
    JOIN crdb_internal.cluster_locks AS lw ON
            lh.lock_key = lw.lock_key
    JOIN crdb_internal.cluster_queries AS q ON
            lw.txn_id = q.txn_id
WHERE
    lh.granted = true
    AND lh.txn_id IS DISTINCT FROM lw.txn_id
    AND lh.table_name = 'bank'
LIMIT
    10
  database_name | table_name | range_id |  lock_key_pretty   |             lock_holder              |             lock_waiter              |                                                    waiting_query                                                     |  wait_duration
----------------+------------+----------+--------------------+--------------------------------------+--------------------------------------+----------------------------------------------------------------------------------------------------------------------+------------------
  bank          | bank       |       50 | /Table/110/1/412/0 | 89d8f3a6-463b-4119-89e9-c797680f35bb | ea5a95cc-923c-4262-b0f7-81014fd19ee1 | UPDATE bank SET balance = CASE id WHEN 351 THEN balance - 39 WHEN 412 THEN balance + 39 END WHERE id IN (351, 412)   | 00:00:01.236359
  bank          | bank       |       50 | /Table/110/1/412/0 | 89d8f3a6-463b-4119-89e9-c797680f35bb | d4a80a8b-ede9-48ea-a7e1-375255f5aabe | UPDATE bank SET balance = CASE id WHEN 351 THEN balance - 551 WHEN 412 THEN balance + 551 END WHERE id IN (351, 412) | 00:00:01.268718
  bank          | bank       |       50 | /Table/110/1/412/0 | 89d8f3a6-463b-4119-89e9-c797680f35bb | 5406a762-1975-4346-ab7d-f32a4ff06469 | UPDATE bank SET balance = CASE id WHEN 351 THEN balance - 395 WHEN 412 THEN balance + 395 END WHERE id IN (351, 412) | 00:00:01.265879
  bank          | bank       |       50 | /Table/110/1/412/0 | 89d8f3a6-463b-4119-89e9-c797680f35bb | be93bcc1-921e-4b8a-9253-98f0848eef2c | UPDATE bank SET balance = CASE id WHEN 351 THEN balance - 725 WHEN 412 THEN balance + 725 END WHERE id IN (351, 412) | 00:00:01.273119
  bank          | bank       |       50 | /Table/110/1/412/0 | 89d8f3a6-463b-4119-89e9-c797680f35bb | a513d77f-9773-48c4-b888-1abbecba12ad | UPDATE bank SET balance = CASE id WHEN 351 THEN balance - 317 WHEN 412 THEN balance + 317 END WHERE id IN (351, 412) | 00:00:01.269164
  bank          | bank       |       50 | /Table/110/1/412/0 | 89d8f3a6-463b-4119-89e9-c797680f35bb | 56d14710-d40f-4bd3-a3f6-f8cc34996bad | UPDATE bank SET balance = CASE id WHEN 351 THEN balance - 758 WHEN 412 THEN balance + 758 END WHERE id IN (351, 412) | 00:00:01.271509
  bank          | bank       |       48 | /Table/110/1/839/0 | 1dd5d45e-98dd-4645-a1c2-9d1656a7c1e2 | 19ecea86-219d-4979-a7ed-04c6fa81e6db | UPDATE bank SET balance = CASE id WHEN 839 THEN balance - 830 WHEN 758 THEN balance + 830 END WHERE id IN (839, 758) | 00:00:00.775891
  bank          | bank       |       50 | /Table/110/1/412/0 | 89d8f3a6-463b-4119-89e9-c797680f35bb | 1a7ce7a8-6145-4d71-a05a-6a22e641a3d5 | UPDATE bank SET balance = CASE id WHEN 351 THEN balance - 711 WHEN 412 THEN balance + 711 END WHERE id IN (351, 412) | 00:00:01.268693
  bank          | bank       |       50 | /Table/110/1/412/0 | 89d8f3a6-463b-4119-89e9-c797680f35bb | 9c9da2b9-a468-45b6-af7f-88f0ade5c9f9 | UPDATE bank SET balance = CASE id WHEN 351 THEN balance - 642 WHEN 412 THEN balance + 642 END WHERE id IN (351, 412) | 00:00:01.267889
  bank          | bank       |       50 | /Table/110/1/412/0 | 89d8f3a6-463b-4119-89e9-c797680f35bb | 997183e4-f1c7-46eb-882b-5b4cf76ff1ab | UPDATE bank SET balance = CASE id WHEN 351 THEN balance - 296 WHEN 412 THEN balance + 296 END WHERE id IN (351, 412) | 00:00:01.269917
(10 rows)

Client sessions holding locks

Run the query below to display a list of sessions that are holding and waiting on locks for the same keys.

This example assumes you are running the bank workload as described in the intermediate example.

icon/buttons/copy
SELECT
    l.database_name,
    l.table_name,
    l.range_id,
    l.lock_key_pretty,
    l.txn_id,
    l.granted,
    s.node_id,
    s.user_name,
    s.client_address
FROM
    crdb_internal.cluster_locks AS l
    JOIN crdb_internal.cluster_transactions AS t ON
            l.txn_id = t.id
    JOIN crdb_internal.cluster_sessions AS s ON
            t.session_id = s.session_id
WHERE
    l.granted = true AND l.table_name = 'bank';
  database_name | table_name | range_id |  lock_key_pretty   |                txn_id                | granted | node_id | user_name | client_address
----------------+------------+----------+--------------------+--------------------------------------+---------+---------+-----------+------------------
  bank          | bank       |       54 | /Table/110/1/140/0 | 7aa534d6-c6df-4a98-9ef5-33ddb7c20618 |  true   |       1 | root      | 127.0.0.1:51398
  bank          | bank       |       53 | /Table/110/1/786/0 | 92490011-e63b-4157-b7e5-6bd17ac6e94c |  true   |       1 | root      | 127.0.0.1:51400
  bank          | bank       |       50 | /Table/110/1/457/0 | 2e815ed3-4178-4eff-a5c5-b04fd6e76d50 |  true   |       1 | root      | 127.0.0.1:51412
  bank          | bank       |       54 | /Table/110/1/137/0 | fd735721-d8a0-4157-b370-00f132bb6263 |  true   |       1 | root      | 127.0.0.1:51425
  bank          | bank       |       54 | /Table/110/1/110/0 | e7acec14-dbf9-4cd9-9ae6-43adac826810 |  true   |       1 | root      | 127.0.0.1:51443
  bank          | bank       |       49 | /Table/110/1/351/0 | 2ff62140-62d8-46e7-9c4a-c3f778519549 |  true   |       1 | root      | 127.0.0.1:51427
  bank          | bank       |       50 | /Table/110/1/412/0 | 2ff62140-62d8-46e7-9c4a-c3f778519549 |  true   |       1 | root      | 127.0.0.1:51427
  bank          | bank       |       48 | /Table/110/1/895/0 | bd676999-37f5-42b4-9278-7b3de5451abe |  true   |       1 | root      | 127.0.0.1:51439
  bank          | bank       |       65 | /Table/110/1/60/0  | 51aacef3-370e-4760-8e8f-60e6e9db4a19 |  true   |       1 | root      | 127.0.0.1:51461
  bank          | bank       |       54 | /Table/110/1/134/0 | 51aacef3-370e-4760-8e8f-60e6e9db4a19 |  true   |       1 | root      | 127.0.0.1:51461
  bank          | bank       |       49 | /Table/110/1/316/0 | 5bffc2fa-43f1-4b76-acfa-2d1d4e09c793 |  true   |       1 | root      | 127.0.0.1:51472
  bank          | bank       |       47 | /Table/110/1/504/0 | 5bffc2fa-43f1-4b76-acfa-2d1d4e09c793 |  true   |       1 | root      | 127.0.0.1:51472
(12 rows)

Count locks held by sessions

Run the query below to show a list of lock counts being held by different sessions.

This example assumes you are running the bank workload as described in the intermediate example.

icon/buttons/copy
SELECT
    l.database_name,
    l.table_name,
    s.user_name,
    s.client_address,
    s.session_id,
    count(lock_key_pretty) AS lock_count
FROM
    crdb_internal.cluster_locks AS l
    JOIN crdb_internal.cluster_transactions AS t ON
            l.txn_id = t.id
    JOIN crdb_internal.cluster_sessions AS s ON
            t.session_id = s.session_id
WHERE
    l.granted = true AND l.table_name = 'bank'
GROUP BY
    l.database_name,
    l.table_name,
    s.user_name,
    s.client_address,
    s.session_id
  database_name | table_name | user_name | client_address  |            session_id            | lock_count
----------------+------------+-----------+-----------------+----------------------------------+-------------
  bank          | bank       | root      | 127.0.0.1:51403 | 17056d4b2f62aeb80000000000000001 |          1
  bank          | bank       | root      | 127.0.0.1:51405 | 17056d4b2f6cc8a80000000000000001 |          1
  bank          | bank       | root      | 127.0.0.1:51421 | 17056d4b2f8acc400000000000000001 |          1
  bank          | bank       | root      | 127.0.0.1:51425 | 17056d4b2f96ab500000000000000001 |          1
  bank          | bank       | root      | 127.0.0.1:51492 | 17056d4b3019be000000000000000001 |          1
  bank          | bank       | root      | 127.0.0.1:51485 | 17056d4b3026f8b80000000000000001 |          2
(6 rows)

Count queries waiting on locks

Run the query below to show a list of keys ordered by how many transactions are waiting on the locks on those keys.

This example assumes you are running the bank workload as described in the intermediate example.

icon/buttons/copy
SELECT
    l.database_name,
    l.table_name,
    l.range_id,
    l.lock_key_pretty,
    count(*) AS waiter_count,
    max(duration) AS longest_wait_duration
FROM
    crdb_internal.cluster_locks AS l
WHERE
    l.granted = false AND l.table_name = 'bank'
GROUP BY
    l.database_name,
    l.table_name,
    l.range_id,
    l.lock_key_pretty
ORDER BY
    waiter_count DESC, longest_wait_duration DESC
LIMIT
    30
  database_name | table_name | range_id |  lock_key_pretty   | waiter_count | longest_wait_duration
----------------+------------+----------+--------------------+--------------+------------------------
  bank          | bank       |       48 | /Table/110/1/895/0 |           81 | 00:00:02.91943
  bank          | bank       |       54 | /Table/110/1/110/0 |           69 | 00:00:02.074832
  bank          | bank       |       53 | /Table/110/1/786/0 |           41 | 00:01:16.871542
  bank          | bank       |       54 | /Table/110/1/137/0 |           10 | 00:01:49.082237
  bank          | bank       |       55 | /Table/110/1/690/0 |            2 | 00:00:44.526906
  bank          | bank       |       50 | /Table/110/1/498/0 |            2 | 00:00:43.473285
(6 rows)

cluster_queries

Column Type Description
query_id STRING Unique query identifier.
txn_id UUID Unique transaction identifier.
node_id INT8 The ID of the node on which the query is executed.
session_id STRING Unique session identifier.
user_name STRING The name of the user that executed the query.
start TIMESTAMP The time that the query started.
query STRING The query string.
client_address STRING The address of the client that initiated the query.
application_name STRING The name of the application that initiated the query.
distributed BOOLEAN Whether the query is executing in a distributed cluster.
phase STRING The phase that the query is in.

View all active queries for the movr application

icon/buttons/copy
SELECT * FROM crdb_internal.cluster_queries where application_name = 'movr';
              query_id             |                txn_id                | node_id |            session_id            | user_name |           start            |                                                          query                                                           | client_address  | application_name | distributed |   phase
-----------------------------------+--------------------------------------+---------+----------------------------------+-----------+----------------------------+--------------------------------------------------------------------------------------------------------------------------+-----------------+------------------+-------------+------------
  16f762fea4cb17180000000000000001 | 7d55d442-6ae6-4062-ba3b-90656e9a6544 |       1 | 16f762c2af917e800000000000000001 | root      | 2022-06-10 22:30:33.907888 | UPSERT INTO vehicle_location_histories VALUES ('amsterdam', '69db0184-4192-4355-99b0-2e2abe7212c2', now(), 109.0, -45.0) | 127.0.0.1:49198 | movr             |    false    | executing
(1 row)

cluster_sessions

Column Type Description
node_id INT8 The ID of the node the session is connected to.
session_id STRING The ID of the session.
user_name STRING The name of the user that initiated the session.
client_address STRING The address of the client that initiated the session.
application_name STRING The name of the application that initiated the session.
active_queries STRING The SQL queries active in the session.
last_active_query STRING The most recently completed SQL query in the session.
session_start TIMESTAMP The timestamp at which the session started.
active_query_start TIMESTAMP The timestamp at which the currently active SQL query in the session started.
kv_txn STRING The ID of the current key-value transaction for the session.
alloc_bytes INT8 The number of bytes allocated by the session.
max_alloc_bytes INT8 The maximum number of bytes allocated by the session.

View all open SQL sessions for the movr application

icon/buttons/copy
SELECT * FROM crdb_internal.cluster_sessions where application_name = 'movr';
  node_id |            session_id            | user_name | client_address  | application_name |                       active_queries                       |               last_active_query               |       session_start       |     active_query_start     |                kv_txn                | alloc_bytes | max_alloc_bytes
----------+----------------------------------+-----------+-----------------+------------------+------------------------------------------------------------+-----------------------------------------------+---------------------------+----------------------------+--------------------------------------+-------------+------------------
        1 | 16f762c2af917e800000000000000001 | root      | 127.0.0.1:49198 | movr             | SELECT city, id FROM vehicles WHERE city = 'washington dc' | SELECT city, id FROM vehicles WHERE city = $1 | 2022-06-10 22:26:16.39059 | 2022-06-10 22:28:00.646594 | 7883cbe3-7cf3-4155-a1a8-82d1211c9ffa |      133120 |          163840
(1 row)

cluster_transactions

Column Type Description
id UUID The unique ID that identifies the transaction.
node_id INT8 The ID of the node the transaction is connected to.
session_id STRING The ID of the session running the transaction.
start TIMESTAMP The time the transaction started.
txn_string STRING The transaction string.
application_name STRING The name of the application that ran the transaction.
num_stmts INT8 The number of statements in the transaction.
num_retries INT8 The number of times the transaction was retried.
num_auto_retries INT8 The number of times the transaction was automatically retried.

View all active transactions for the movr application

icon/buttons/copy
SELECT * FROM crdb_internal.cluster_transactions where application_name = 'movr';
                   id                  | node_id |            session_id            |           start            |                                                                                                                                            txn_string                                                                                                                                            | application_name | num_stmts | num_retries | num_auto_retries
---------------------------------------+---------+----------------------------------+----------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------+-----------+-------------+-------------------
  9cfb2bbe-e1d8-4650-95d5-7a3fd052c6a7 |       1 | 16f762c2af917e800000000000000001 | 2022-06-10 22:26:20.370946 | "sql txn" meta={id=9cfb2bbe key=/Table/109/1/"rome"/"\xbf\x92\xe2<̯D\v\x94M\x83b0\x1b-\x82"/2022-06-10T22:26:20.370935Z/0 pri=0.00109794 epo=0 ts=1654899980.370940000,0 min=1654899980.370940000,0 seq=1} lock=true stat=PENDING rts=1654899980.370940000,0 wto=false gul=1654899980.870940000,0 | movr             |         1 |           0 |                0
(1 row)

index_usage_statistics

Contains one row for each index in the current database surfacing usage statistics for that specific index. This view is updated every time a transaction is committed. Each user-submitted statement on the specified index is counted as a use of that index and increments corresponding counters in this view. System and internal queries (such as scans for gathering statistics) are not counted.

Column Type Description
table_id INT8 Unique table identifier.
index_id INT8 Unique index identifier.
total_reads INT8 Number of times an index was selected for a read.
last_read TIMESTAMPTZ Time of last read.

You can reset the index usages statistics by invoking the function crdb_internal.reset_index_usage_stats(). For example:

icon/buttons/copy
SELECT crdb_internal.reset_index_usage_stats();
  crdb_internal.reset_index_usage_stats
-----------------------------------------
                  true
(1 row)

View index statistics by table and index name

To view index usage statistics by table and index name, join with table_indexes:

icon/buttons/copy
SELECT  ti.descriptor_name as table_name, ti.index_name, total_reads
FROM  crdb_internal.index_usage_statistics AS us
JOIN crdb_internal.table_indexes ti
ON us.index_id = ti.index_id AND us.table_id = ti.descriptor_id
ORDER BY total_reads desc;
          table_name         |                  index_name                   | total_reads
-----------------------------+-----------------------------------------------+--------------
  vehicles                   | vehicles_auto_index_fk_city_ref_users         |      412266
  rides                      | rides_pkey                                    |      216137
  users                      | users_pkey                                    |       25709
  vehicles                   | vehicles_pkey                                 |       17185
  promo_codes                | promo_codes_pkey                              |        4274
  user_promo_codes           | user_promo_codes_pkey                         |        2138
  rides                      | rides_auto_index_fk_city_ref_users            |           1
  rides                      | rides_auto_index_fk_vehicle_city_ref_vehicles |           1
  vehicle_location_histories | vehicle_location_histories_pkey               |           1
(9 rows)

Determine which indexes haven't been used in the past week

To determine if there are indexes that have become stale and are no longer needed, show which indexes haven't been used during the past week with the following query:

icon/buttons/copy
SELECT  ti.descriptor_name as table_name, ti.index_name, total_reads
FROM  crdb_internal.index_usage_statistics AS us
JOIN crdb_internal.table_indexes ti
ON us.index_id = ti.index_id AND us.table_id = ti.descriptor_id
WHERE last_read < NOW() - INTERVAL '1 WEEK'
ORDER BY total_reads desc;

Determine which indexes are no longer used

View which indexes are no longer used with the following query:

icon/buttons/copy
SELECT  ti.descriptor_name as table_name, ti.index_name, total_reads
FROM crdb_internal.index_usage_statistics AS us
JOIN crdb_internal.table_indexes ti
ON us.index_id = ti.index_id AND us.table_id = ti.descriptor_id
WHERE total_reads = 0;

statement_statistics

Column Type Description
aggregated_ts TIMESTAMPTZ NOT NULL The time that statistics aggregation started.
fingerprint_id BYTES NOT NULL Unique identifier of the statement statistics. This is constructed using the statement fingerprint text, and statement metadata (e.g., query type, database name, etc.)
transaction_fingerprint_id BYTES NOT NULL Uniquely identifies a transaction statistics. The transaction fingerprint ID that this statement statistic belongs to.
plan_hash BYTES NOT NULL Uniquely identifies a query plan that was executed by the current statement. The query plan can be retrieved from the sampled_plan column.
app_name STRING NOT NULL The name of the application that executed the statement.
metadata JSONB NOT NULL Metadata that describes the statement. See metadata column.
statistics JSONB NOT NULL Statistics for the statement. See statistics column.
sampled_plan JSONB NOT NULL The sampled query plan of the current statement statistics. This column is unfilled if there is no sampled query plan.
aggregation_interval INTERVAL NOT NULL The interval over which statistics are aggregated.
index_recommendations STRING[] NOT NULL An array of strings containing index recommendations of the format {type} : {sql query}.

fingerprint_id column

The value is in hexadecimal format. The following examples show how to use this value to query statement_statistics:

  1. Add the escape character \x at the start of the fingerprint_id:
    icon/buttons/copy
> SELECT * FROM crdb_internal.statement_statistics WHERE fingerprint_id='\x97ffc170783445fd';
  1. Encode the fingerprint_id as hex:
    icon/buttons/copy
> SELECT * FROM crdb_internal.statement_statistics WHERE encode(fingerprint_id, 'hex')='97ffc170783445fd';

metadata column

Field Type Description
db STRING The database on which the statement is executed.
distsql BOOLEAN Whether the statement is being executed by the Distributed SQL (DistSQL) engine.
failed BOOLEAN Whether the statement execution failed.
fullScan BOOLEAN Whether the statement performed a full scan of the table.
implicitTxn BOOLEAN Whether the statement executed in an implicit transaction.
query STRING The statement string.
querySummary STRING The statement string summary.
stmtTyp STRING The type of SQL statement: "TypeDDL", "TypeDML", "TypeDCL", or "TypeTCL". These types map to the CockroachDB statement types data definition language (DDL), data manipulation language (DML), data control language (DCL), and transaction control language (TCL).
vec BOOLEAN Whether the statement executed in the vectorized query engine.

statistics column

The DB Console Statements and Statement Fingerprint pages display information from statistics.

The statistics column contains a JSONB object with statistics and execution_statistics subobjects. statistics are always populated and are updated each time a new statement of that statement fingerprint is executed. execution_statistics are collected using sampling. CockroachDB probabilistically runs a query with tracing enabled to collect fine-grained statistics of the query execution.

The NumericStat type tracks two running values: the running mean mean and the running sum of squared differences sqDiff from the mean. You can use these statistics along with the total number of values to compute the variance using Welford's method. CockroachDB computes the variance and displays it along with mean in the Statements table.

Field Type Description
execution_statistics -> cnt INT64 The number of times execution statistics were recorded.
execution_statistics -> contentionTime -> [mean|sqDiff] NumericStat The time the statement spent contending for resources before being executed.
execution_statistics -> maxDiskUsage -> [mean|sqDiff] NumericStat The maximum temporary disk usage that occurred while executing this statement. This is set in cases where a query had to spill to disk, e.g., when performing a large sort where not all of the tuples fit in memory.
execution_statistics -> maxMemUsage -> [mean|sqDiff] NumericStat The maximum memory usage that occurred on a node.
execution_statistics -> networkBytes -> [mean|sqDiff] NumericStat The number of bytes sent over the network.
execution_statistics -> networkMsgs -> [mean|sqDiff] NumericStat The number of messages sent over the network.
statistics -> bytesRead -> [mean|sqDiff] NumericStat The number of bytes read from disk.
statistics -> cnt INT8 The total number of times this statement was executed since the begin of the aggregation period.
statistics -> firstAttemptCnt INT8 The total number of times a first attempt was executed (either the one time in explicitly committed statements, or the first time in implicitly committed statements with implicit retries).
statistics -> lastExecAt TIMESTAMP The last timestamp the statement was executed.
statistics -> maxRetries INT8 The maximum observed number of automatic retries in the aggregation period.
statistics -> nodes Array of INT64 An ordered list of nodes IDs on which the statement was executed.
statistics -> numRows -> [mean|sqDiff] NumericStat The number of rows returned or observed.
statistics -> ovhLat -> [mean|sqDiff] NumericStat The difference between svcLat and the sum of parseLat+planLat+runLat latencies.
statistics -> parseLat -> [mean|sqDiff] NumericStat The time to transform the SQL string into an abstract syntax tree (AST).
statistics -> planGists String A sequence of bytes representing the flattened tree of operators and various operator specific metadata of the statement plan.
statistics -> planLat -> [mean|sqDiff] NumericStat The time to transform the AST into a logical query plan.
statistics -> rowsRead -> [mean|sqDiff] NumericStat The number of rows read from disk.
statistics -> rowsWritten -> [mean|sqDiff] NumericStat The number of rows written to disk.
statistics -> runLat -> [mean|sqDiff] NumericStat The time to run the query and fetch or compute the result rows.
statistics -> svcLat -> [mean|sqDiff] NumericStat The time to service the query, from start of parse to end of execute.

View historical statement statistics and the sampled logical plan per fingerprint

This example command shows how to query the two most important JSON columns: metadata and statistics. It displays the first 60 characters of query text, statement statistics, and sampled plan for DDL and DML statements for the movr demo database:

icon/buttons/copy
SELECT substring(metadata ->> 'query',1,60) AS statement_text,
   metadata ->> 'stmtTyp' AS statement_type,
   metadata -> 'distsql' AS is_distsql,
   metadata -> 'fullScan' AS has_full_scan,
   metadata -> 'vec' AS used_vec,
   statistics -> 'execution_statistics' -> 'contentionTime' -> 'mean' AS contention_time_mean,
   statistics -> 'statistics' -> 'cnt' AS execution_count,
   statistics -> 'statistics' -> 'firstAttemptCnt' AS num_first_attempts,
   statistics -> 'statistics' -> 'numRows' -> 'mean' AS num_rows_returned_mean,
   statistics -> 'statistics' -> 'rowsRead' -> 'mean' AS num_rows_read_mean,
   statistics -> 'statistics' -> 'runLat' -> 'mean' AS runtime_latency_mean,
   jsonb_pretty(sampled_plan) AS sampled_plan
FROM movr.crdb_internal.statement_statistics
WHERE metadata @> '{"db":"movr"}' AND (metadata @> '{"stmtTyp":"TypeDDL"}' OR metadata @> '{"stmtTyp":"TypeDML"}') LIMIT 20;
                         statement_text                        | statement_type | is_distsql | has_full_scan | used_vec | contention_time_mean | execution_count | num_first_attempts | num_rows_returned_mean | num_rows_read_mean | runtime_latency_mean |                                                         sampled_plan
---------------------------------------------------------------+----------------+------------+---------------+----------+----------------------+-----------------+--------------------+------------------------+--------------------+----------------------+--------------------------------------------------------------------------------------------------------------------------------
  ALTER TABLE rides ADD FOREIGN KEY (city, rider_id) REFERENCE | TypeDDL        | false      | false         | true     |                    0 |               1 |                  1 |                      0 |                  0 |             0.007348 | {
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Children": [],
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Name": "alter table"
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      | }
  ALTER TABLE rides ADD FOREIGN KEY (vehicle_city, vehicle_id) | TypeDDL        | false      | false         | true     |                    0 |               1 |                  1 |                      0 |                  0 |             0.006618 | {
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Children": [],
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Name": "alter table"
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      | }
  ALTER TABLE rides SCATTER FROM ('_', '_') TO ('_', '_')      | TypeDML        | false      | false         | true     |                    0 |               8 |                  8 |                      1 |                  0 |           0.00066175 | {
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Children": [],
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Name": "scatter"
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      | }
  ALTER TABLE rides SPLIT AT VALUES ('_', '_')                 | TypeDML        | false      | false         | true     |                    0 |               8 |                  8 |                      1 |                  0 |          0.031441875 | {
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Children": [
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |         {
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |             "Children": [],
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |             "Name": "values",
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |             "Size": "2 columns, 1 row"
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |         }
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     ],
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Name": "split"
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      | }
  ALTER TABLE user_promo_codes ADD FOREIGN KEY (city, user_id) | TypeDDL        | false      | false         | true     |                    0 |               1 |                  1 |                      0 |                  0 |             0.008143 | {
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Children": [],
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Name": "alter table"
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      | }
  ALTER TABLE users SCATTER FROM ('_', '_') TO ('_', '_')      | TypeDML        | false      | false         | true     |                    0 |               8 |                  8 |                      1 |                  0 |             0.001272 | {
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Children": [],
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Name": "scatter"
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      | }
  ALTER TABLE users SPLIT AT VALUES ('_', '_')                 | TypeDML        | false      | false         | true     |                    0 |               8 |                  8 |                      1 |                  0 |          0.179651125 | {
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Children": [
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |         {
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |             "Children": [],
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |             "Name": "values",
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |             "Size": "2 columns, 1 row"
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |         }
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     ],
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Name": "split"
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      | }
  ALTER TABLE vehicle_location_histories ADD FOREIGN KEY (city | TypeDDL        | false      | false         | true     |                    0 |               1 |                  1 |                      0 |                  0 |             0.007684 | {
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Children": [],
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Name": "alter table"
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      | }
  ALTER TABLE vehicles ADD FOREIGN KEY (city, owner_id) REFERE | TypeDDL        | false      | false         | true     |                    0 |               1 |                  1 |                      0 |                  0 |             0.004085 | {
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Children": [],
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Name": "alter table"
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      | }
  ALTER TABLE vehicles SCATTER FROM ('_', '_') TO ('_', '_')   | TypeDML        | false      | false         | true     |                    0 |               8 |                  8 |                      1 |                  0 |             0.000702 | {
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Children": [],
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Name": "scatter"
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      | }
  ALTER TABLE vehicles SPLIT AT VALUES ('_', '_')              | TypeDML        | false      | false         | true     |                    0 |               8 |                  8 |                      1 |                  0 |          0.008966375 | {
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Children": [
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |         {
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |             "Children": [],
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |             "Name": "values",
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |             "Size": "2 columns, 1 row"
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |         }
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     ],
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Name": "split"
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      | }
  CREATE DATABASE movr                                         | TypeDDL        | false      | false         | true     |                    0 |               1 |                  1 |                      0 |                  0 |             0.001397 | {
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Children": [],
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Name": "create database"
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      | }
  CREATE TABLE IF NOT EXISTS promo_codes (code VARCHAR NOT NUL | TypeDDL        | false      | false         | true     |                    0 |               1 |                  1 |                      0 |                  0 |             0.001789 | {
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Children": [],
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Name": "create table"
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      | }
  CREATE TABLE IF NOT EXISTS rides (id UUID NOT NULL, city VAR | TypeDDL        | false      | false         | true     |                    0 |               1 |                  1 |                      0 |                  0 |             0.002374 | {
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Children": [],
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Name": "create table"
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      | }
  CREATE TABLE IF NOT EXISTS user_promo_codes (city VARCHAR NO | TypeDDL        | false      | false         | true     |                    0 |               1 |                  1 |                      0 |                  0 |             0.006318 | {
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Children": [],
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Name": "create table"
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      | }
  CREATE TABLE IF NOT EXISTS users (id UUID NOT NULL, city VAR | TypeDDL        | false      | false         | true     |                    0 |               1 |                  1 |                      0 |                  0 |             0.002014 | {
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Children": [],
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Name": "create table"
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      | }
  CREATE TABLE IF NOT EXISTS vehicle_location_histories (city  | TypeDDL        | false      | false         | true     |                    0 |               1 |                  1 |                      0 |                  0 |             0.001906 | {
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Children": [],
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Name": "create table"
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      | }
  CREATE TABLE IF NOT EXISTS vehicles (id UUID NOT NULL, city  | TypeDDL        | false      | false         | true     |                    0 |               1 |                  1 |                      0 |                  0 |             0.003346 | {
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Children": [],
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Name": "create table"
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      | }
  INSERT INTO promo_codes VALUES ($1, $2, __more3__), (__more9 | TypeDML        | false      | false         | true     |                    0 |             250 |                250 | 1E+3                   |                  0 | 0.010470284000000002 | {
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Auto Commit": "",
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Children": [],
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Into": "promo_codes(code, description, creation_time, expiration_time, rules)",
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Name": "insert fast path",
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Size": "5 columns, 1000 rows"
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      | }
  INSERT INTO rides VALUES ($1, $2, __more8__), (__more900__)  | TypeDML        | false      | false         | true     |                    0 |             125 |                125 | 1E+3                   |                  0 | 0.054189928000000005 | {
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Auto Commit": "",
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Children": [
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |         {
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |             "Children": [
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |                 {
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |                     "Children": [],
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |                     "Name": "values",
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |                     "Size": "10 columns, 1000 rows"
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |                 }
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |             ],
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |             "Estimated Row Count": "1,000",
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |             "Name": "render"
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |         }
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     ],
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Into": "rides(id, city, vehicle_city, rider_id, vehicle_id, start_address, end_address, start_time, end_time, revenue)",
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      |     "Name": "insert"
                                                               |                |            |               |          |                      |                 |                    |                        |                    |                      | }

Detect suboptimal and regressed plans

Historical plans are stored in plan gists in statistics->'statistics'->'planGists'. To detect suboptimal and regressed plans over time you can compare plans for the same query by extracting them from the plan gists.

Suppose you wanted to compare plans of the following query:

icon/buttons/copy
SELECT
  name, count(rides.id) AS sum
FROM
  users JOIN rides ON users.id = rides.rider_id
WHERE
  rides.start_time BETWEEN '2018-12-31 00:00:00' AND '2020-01-01 00:00:00'
GROUP BY
  name
ORDER BY
  sum DESC
LIMIT
  10;

To decode plan gists, use the crdb_internal.decode_plan_gist function, as shown in the following query. The example shows the performance impact of adding an index on the start_time column in the rides table. The first row of the output shows the improved performance (reduced number of rows read and latency) after the index was added. The second row shows the query, which performs a full scan on the rides table, before the index was added.

icon/buttons/copy
SELECT
substring(metadata ->> 'query',1,60) AS statement_text,
  string_agg(  crdb_internal.decode_plan_gist(statistics->'statistics'->'planGists'->>0), '
  ') AS plan,
  max(aggregated_ts) as timestamp_interval,
  max(statistics -> 'statistics' -> 'rowsRead' -> 'mean') AS num_rows_read_mean,
  max(statistics -> 'statistics' -> 'runLat' -> 'mean') AS runtime_latency_mean,
  statistics->'statistics'->'planGists'->>0 as plan_id
FROM movr.crdb_internal.statement_statistics
WHERE substring(metadata ->> 'query',1,35)='SELECT name, count(rides.id) AS sum'
group by metadata ->> 'query', statistics->'statistics'->'planGists'->>0;
                         statement_text                        |                        plan                         |   timestamp_interval   | num_rows_read_mean | runtime_latency_mean |                     plan_id
---------------------------------------------------------------+-----------------------------------------------------+------------------------+--------------------+----------------------+---------------------------------------------------
  SELECT name, count(rides.id) AS sum FROM users JOIN rides ON | • top-k                                             | 2022-04-12 22:00:00+00 |              24786 |             0.028525 | AgHYAQgAiAECAAAB1AEEAAUAAAAJAAICAAAFAgsCGAYE
                                                               |   │ order                                           |                        |                    |                      |
                                                               |   │                                                 |                        |                    |                      |
                                                               |   └── • group (hash)                                |                        |                    |                      |
                                                               |       │ group by: rider_id                          |                        |                    |                      |
                                                               |       │                                             |                        |                    |                      |
                                                               |       └── • hash join                               |                        |                    |                      |
                                                               |           │ equality: (rider_id) = (id)             |                        |                    |                      |
                                                               |           │                                         |                        |                    |                      |
                                                               |           ├── • scan                                |                        |                    |                      |
                                                               |           │     table: rides@rides_start_time_idx   |                        |                    |                      |
                                                               |           │     spans: 1 span                       |                        |                    |                      |
                                                               |           │                                         |                        |                    |                      |
                                                               |           └── • scan                                |                        |                    |                      |
                                                               |                 table: users@users_city_id_name_key |                        |                    |                      |
                                                               |                 spans: FULL SCAN                    |                        |                    |                      |
  SELECT name, count(rides.id) AS sum FROM users JOIN rides ON | • top-k                                             | 2022-04-12 22:00:00+00 | 1.375E+5           |             0.279083 | AgHYAQIAiAEAAAADAdQBBAAFAAAACQACAgAABQILAhgGBA==
                                                               |   │ order                                           |                        |                    |                      |
                                                               |   │                                                 |                        |                    |                      |
                                                               |   └── • group (hash)                                |                        |                    |                      |
                                                               |       │ group by: rider_id                          |                        |                    |                      |
                                                               |       │                                             |                        |                    |                      |
                                                               |       └── • hash join                               |                        |                    |                      |
                                                               |           │ equality: (rider_id) = (id)             |                        |                    |                      |
                                                               |           │                                         |                        |                    |                      |
                                                               |           ├── • filter                              |                        |                    |                      |
                                                               |           │   │                                     |                        |                    |                      |
                                                               |           │   └── • scan                            |                        |                    |                      |
                                                               |           │         table: rides@rides_pkey         |                        |                    |                      |
                                                               |           │         spans: FULL SCAN                |                        |                    |                      |
                                                               |           │                                         |                        |                    |                      |
                                                               |           └── • scan                                |                        |                    |                      |
                                                               |                 table: users@users_city_id_name_key |                        |                    |                      |
                                                               |                 spans: FULL SCAN                    |                        |                    |                      |
(2 rows)

transaction_contention_events

Contains one row for each transaction contention event.

Requires either the VIEWACTIVITY or VIEWACTIVITYREDACTED system privilege (or the legacy VIEWACTIVITY or VIEWACTIVITYREDACTED role option) to access. If you have the VIEWACTIVITYREDACTED privilege, contending_key will be redacted.

Contention events are stored in memory. You can control the amount of contention events stored per node via the sql.contention.event_store.capacity cluster setting.

The sql.contention.event_store.duration_threshold cluster setting specifies the minimum contention duration to cause the contention events to be collected into the crdb_internal.transaction_contention_events table. The default value is 0. If contention event collection is overwhelming the CPU or memory you can raise this value to reduce the load.

Column Type Description
collection_ts TIMESTAMPTZ NOT NULL The timestamp when the transaction contention event was collected.
blocking_txn_id UUID NOT NULL The ID of the blocking transaction. You can join this column into the cluster_contention_events table.
blocking_txn_fingerprint_id BYTES NOT NULL The ID of the blocking transaction fingerprint. To surface historical information about the transactions that caused the contention, you can join this column into the statement_statistics and transaction_statistics tables to surface historical information about the transactions that caused the contention.
waiting_txn_id UUID NOT NULL The ID of the waiting transaction. You can join this column into the cluster_contention_events table.
waiting_txn_fingerprint_id BYTES NOT NULL The ID of the waiting transaction fingerprint. To surface historical information about the transactions that caused the contention, you can join this column into the statement_statistics and transaction_statistics tables.
contention_duration INTERVAL NOT NULL The interval of time the waiting transaction spent waiting for the blocking transaction.
contending_key BYTES NOT NULL The key on which the transactions contended.

Example

The following example shows how to join the transaction_contention_events table with transaction_statistics and statement_statistics tables to extract blocking and waiting transaction information.

  1. Display contention table removing in-progress transactions.

    icon/buttons/copy
    SELECT
      collection_ts,
      blocking_txn_id,
      encode(blocking_txn_fingerprint_id, 'hex') as blocking_txn_fingerprint_id,
      waiting_txn_id,
      encode(waiting_txn_fingerprint_id, 'hex') as waiting_txn_fingerprint_id
    FROM
      crdb_internal.transaction_contention_events
    WHERE
      encode(blocking_txn_fingerprint_id, 'hex') != '0000000000000000' AND encode(waiting_txn_fingerprint_id, 'hex') != '0000000000000000';
    
              collection_ts         |           blocking_txn_id            | blocking_txn_fingerprint_id |            waiting_txn_id            | waiting_txn_fingerprint_id
    --------------------------------+--------------------------------------+-----------------------------+--------------------------------------+-----------------------------
      2022-04-11 23:41:56.951687+00 | 921e3d5b-22ab-4a94-a7a4-407e143cfa73 | 79ac4a19cff03b60            | 74ac5efa-a1e4-4c24-a648-58b82a192f9d | b7a98a63d6932458
      2022-04-12 22:55:55.968825+00 | 25c75267-c091-44d4-8c33-8f5247409da5 | f07b4a806f8b7a2e            | 5397acb0-69f3-4c5c-b7a3-75d51180df44 | b7a98a63d6932458
    (2 rows)
    
  2. Display counts for each blocking and waiting transaction fingerprint pair.

    icon/buttons/copy
    SELECT
      encode(hce.blocking_txn_fingerprint_id, 'hex') as blocking_txn_fingerprint_id,
      encode(hce.waiting_txn_fingerprint_id, 'hex') as waiting_txn_fingerprint_id,
      count(*) AS contention_count
    FROM
      crdb_internal.transaction_contention_events hce
    WHERE
      encode(blocking_txn_fingerprint_id, 'hex') != '0000000000000000' AND encode(waiting_txn_fingerprint_id, 'hex') != '0000000000000000'
    GROUP BY
      hce.blocking_txn_fingerprint_id, hce.waiting_txn_fingerprint_id
    ORDER BY
      contention_count
    DESC;
    
      blocking_txn_fingerprint_id | waiting_txn_fingerprint_id | contention_count
    ------------------------------+----------------------------+-------------------
      79ac4a19cff03b60            | b7a98a63d6932458           |                1
      f07b4a806f8b7a2e            | b7a98a63d6932458           |                1
    (3 rows)
    
  3. Join to show blocking statements text.

    icon/buttons/copy
    SELECT DISTINCT
      hce.blocking_statement,
      substring(ss2.metadata ->> 'query', 1, 60) AS waiting_statement,
      hce.contention_count
    FROM (SELECT
            blocking_txn_fingerprint_id,
            waiting_txn_fingerprint_id,
            contention_count,
            substring(ss.metadata ->> 'query', 1, 60) AS blocking_statement
          FROM (SELECT
                  encode(blocking_txn_fingerprint_id, 'hex') as blocking_txn_fingerprint_id,
                  encode(waiting_txn_fingerprint_id, 'hex') as waiting_txn_fingerprint_id,
                  count(*) AS contention_count
                FROM
                  crdb_internal.transaction_contention_events
                GROUP BY
                  blocking_txn_fingerprint_id, waiting_txn_fingerprint_id
                ),
              crdb_internal.statement_statistics ss
          WHERE
            blocking_txn_fingerprint_id = encode(ss.transaction_fingerprint_id, 'hex')) hce,
          crdb_internal.statement_statistics ss2
    WHERE
      hce.blocking_txn_fingerprint_id != '0000000000000000' AND
      hce.waiting_txn_fingerprint_id != '0000000000000000' AND
      hce.waiting_txn_fingerprint_id = encode(ss2.transaction_fingerprint_id, 'hex')
    ORDER BY
      contention_count
    DESC;
    
                       blocking_statement                   |                      waiting_statement                       | contention_count
    --------------------------------------------------------+--------------------------------------------------------------+-------------------
      CREATE UNIQUE INDEX ON users (city, id, name)         | SELECT status, payload, progress, crdb_internal.sql_liveness |                1
      CREATE INDEX ON rides (start_time) STORING (rider_id) | SELECT status, payload, progress, crdb_internal.sql_liveness |                1
    (2 rows)
    

transaction_statistics

Column Type Description
aggregated_ts TIMESTAMPTZ The time that statistics aggregation started.
fingerprint_id BYTES The ID of the transaction fingerprint.
app_name STRING The name of the application that executed the transaction.
metadata JSONB Metadata that describes the transaction. See metadata column.
statistics JSONB Statistics for the transaction. See statistics column.
aggregation_interval INTERVAL The interval of time over which statistics are aggregated.

View historical transaction statistics per fingerprint

This example command shows how to query the two most important JSON columns: metadata and statistics. It displays the statistics for transactions on the movr demo database:

icon/buttons/copy
SELECT
   metadata -> 'stmtFingerprintIDs' AS statement_fingerprint_id,
   statistics -> 'execution_statistics' -> 'cnt' AS execution_count,
   statistics -> 'execution_statistics' -> 'contentionTime' -> 'mean' AS contention_time_mean,
   statistics -> 'execution_statistics' -> 'maxDiskUsage'  -> 'mean' AS max_disk_usage_mean,
   statistics -> 'execution_statistics' -> 'maxMemUsage'  -> 'mean' AS max_mem_usage_mean,
   statistics -> 'execution_statistics' -> 'networkBytes' -> 'mean' AS num_ntwk_bytes_mean,
   statistics -> 'execution_statistics' -> 'networkMsgs' -> 'mean' AS num_ntwk_msgs_mean,
   statistics -> 'statistics' -> 'bytesRead' -> 'mean' AS bytes_read_mean,
   statistics -> 'statistics' -> 'cnt' AS count,
   statistics -> 'statistics' -> 'commitLat' -> 'mean' AS commit_lat_mean,
   statistics -> 'statistics' -> 'maxRetries' AS max_retries,
   statistics -> 'statistics' -> 'numRows'  -> 'mean' AS num_rows_mean,
   statistics -> 'statistics' -> 'retryLat' -> 'mean' AS retry_latency_mean,
   statistics -> 'statistics' -> 'rowsRead' -> 'mean' AS num_rows_read_mean,
   statistics -> 'statistics' -> 'rowsWritten' -> 'mean' AS num_rows_written_mean,
   statistics -> 'statistics' -> 'svcLat' -> 'mean' AS service_lat_mean
FROM crdb_internal.transaction_statistics WHERE app_name = 'movr' LIMIT 20;
  statement_fingerprint_id | execution_count | contention_time_mean | max_disk_usage_mean | max_mem_usage_mean | num_ntwk_bytes_mean | num_ntwk_msgs_mean |  bytes_read_mean   | count |     commit_lat_mean      | max_retries | num_rows_mean | retry_latency_mean | num_rows_read_mean | num_rows_written_mean |   service_lat_mean
---------------------------+-----------------+----------------------+---------------------+--------------------+---------------------+--------------------+--------------------+-------+--------------------------+-------------+---------------+--------------------+--------------------+-----------------------+------------------------
  ["ae6bf00068ea788b"]     |               7 |                    0 |                   0 | 2.048E+4           |                   0 |                  0 | 299.35812133072403 |   511 |   0.00000699021526418786 |           0 |             1 |                  0 | 1.9315068493150669 |                     0 | 0.0020743385518591003
  ["ae6bf00068ea788b"]     |               7 |                    0 |                   0 | 2.048E+4           |                   0 |                  0 | 300.61684210526295 |   475 |   0.00000655368421052631 |           0 |             1 |                  0 | 1.9389473684210534 |                     0 | 0.0019613578947368414
  ["bd6cff84f3c76319"]     |               6 |                    0 |                   0 | 2.048E+4           |                   0 |                  0 | 215.77310924369766 |   714 |  0.000008922969187675072 |           0 |             1 |                  0 | 1.9621848739495786 |                     0 |   0.00228533193277311
  ["bd6cff84f3c76319"]     |               7 |                    0 |                   0 | 2.048E+4           |                   0 |                  0 |  214.7635658914728 |   774 | 0.0000071511627906976775 |           0 |             1 |                  0 | 1.9547803617571062 |                     0 |  0.002103399224806201
  ["cfc8fc0503422c76"]     |               3 |                    0 |                   0 | 1.024E+4           |                   0 |                  0 |                  0 |   368 |    0.0013085163043478267 |           0 |             1 |                  0 |                  0 |                     1 |  0.001331747282608696
  ["cfc8fc0503422c76"]     |               4 |                    0 |                   0 | 1.024E+4           |                   0 |                  0 |                  0 |   361 |    0.0011630997229916886 |           0 |             1 |                  0 |                  0 |                     1 | 0.0019714072022160665
  ["dc9d9b4fcdd7511e"]     |               1 |                    0 |                   0 | 4.096E+4           |                 152 |                  3 |                  0 |   116 |  0.000006956896551724138 |           0 |             1 |                  0 |                  0 |                     0 | 0.0014110603448275855
  ["dc9d9b4fcdd7511e"]     |               1 |                    0 |                   0 | 4.096E+4           |                 152 |                  3 |                  0 |   126 |  0.000006730158730158729 |           0 |             1 |                  0 |                  0 |                     0 | 0.0013825634920634914
  ["22295b56d9b279f5"]     |               4 |                    0 |                   0 | 1.024E+4           |                   0 |                  0 |                  0 |   140 |  0.000007021428571428573 |           0 |             1 |                  0 |                  0 |                     1 | 0.0021642071428571432
  ["22295b56d9b279f5"]     |               0 |                    0 |                   0 |                  0 |                   0 |                  0 |                  0 |   116 |  0.000008215517241379309 |           0 |             1 |                  0 |                  0 |                     1 | 0.0021244137931034483
  ["051aca13769620d3"]     |               0 |                    0 |                   0 |                  0 |                   0 |                  0 |                  0 |    95 |    0.0012012000000000008 |           0 |             1 |                  0 |                  1 |                     1 |  0.002633694736842105
  ["051aca13769620d3"]     |               0 |                    0 |                   0 |                  0 |                   0 |                  0 |                  0 |    93 |     0.001323118279569892 |           0 |             1 |                  0 |                  1 |                     1 | 0.0024401720430107525
  ["1b8e962ebb4b2c5c"]     |               2 |                    0 |                   0 | 1.024E+4           |                   0 |                  0 |                  0 |   132 |    0.0011926818181818182 |           0 |             1 |                  0 |                  0 |                     1 | 0.0023831893939393945
  ["1b8e962ebb4b2c5c"]     |               0 |                    0 |                   0 |                  0 |                   0 |                  0 |                  0 |   110 |    0.0013019909090909092 |           0 |             1 |                  0 |                  0 |                     1 | 0.0026221727272727276
  ["15489d7704332101"]     |             125 |                    0 |                   0 | 5.12E+4            |                   0 |                  0 |                  0 | 12199 |    0.0014255228297401419 |           0 |             1 |                  0 |                  1 |                     1 |  0.004390958439216331
  ["15489d7704332101"]     |             114 |                    0 |                   0 | 5.12E+4            |                   0 |                  0 |                  0 | 12380 |    0.0014023091276251975 |           0 |             1 |                  0 |                  1 |                     1 |  0.004440339660743126
  ["1165541b8979eb40"]     |               1 |                    0 |                   0 | 3.072E+4           |                 208 |                  3 | 482.75193798449624 |   129 | 0.0000073410852713178325 |           0 |             1 |                  0 |  1.984496124031008 |                     0 |  0.002383465116279069
  ["1165541b8979eb40"]     |               1 |                    0 |                   0 | 2.048E+4           |                   0 |                  0 | 473.58394160583924 |   137 |  0.000006656934306569342 |           0 |             1 |                  0 | 1.9416058394160585 |                     0 |  0.001756532846715328
  ["485a374e9e1c11d0"]     |              11 |                    0 |                   0 | 1.024E+4           |                   0 |                  0 |                  0 |   480 |    0.0014361895833333342 |           0 |             1 |                  0 |                  0 |                     1 | 0.0027399666666666684
  ["485a374e9e1c11d0"]     |               9 |                    0 |                   0 | 1.024E+4           |                   0 |                  0 |                  0 |   465 |    0.0011626645161290328 |           0 |             1 |                  0 |                  0 |                     1 | 0.0026638344086021525

See also


Yes No
On this page

Yes No