SET {session variable}

The SET statement can modify one of the session configuration variables. These can also be queried via SHOW. By default, session variable values are set for the duration of the current session.

CockroachDB supports setting session variables for the duration of a single transaction, using the LOCAL keyword.

Note:

The SET statement for session variables is unrelated to the other SET TRANSACTION and SET CLUSTER SETTING statements.

Warning:

In some cases, client drivers can drop and restart the connection to the server. When this happens, any session configurations made with SET statements are lost. It is therefore more reliable to configure the session in the client's connection string. For examples in different languages, see the Build an App with CockroachDB tutorials.

Required privileges

To set the role session variable, the current user must be a member of the admin role, or a member of the target role.

All other session variables do not require privileges to modify.

Synopsis

The SET statement can set a session variable for the duration of the current session (SET {variable}/SET SESSION {variable}), or for the duration of a single transaction (SET LOCAL {variable}).

SET SESSION

SET SESSION var_name = TO var_value ,
Note:

By default, session variables are set for the duration of the current session. As a result, SET {variable} and SET SESSION {variable} are equivalent.

SET LOCAL

SET LOCAL var_name = TO var_value ,
Note:

SET LOCAL is compatible with savepoints. Executing a ROLLBACK, ROLLBACK TO SAVEPOINT, or RELEASE TO SAVEPOINT statement rolls back any variables set by SET LOCAL.

Parameters

Parameter Description
var_name The name of the session variable to set. The variable name is case-insensitive.
var_value The value, or list of values, to assign to the session variable.

Supported variables

Variable name Description Initial value Modify with SET? View with SHOW?
application_name The current application name for statistics collection. Empty string, or cockroach for sessions from the built-in SQL client. Yes Yes
bytea_output The mode for conversions from STRING to BYTES. hex Yes Yes
client_min_messages The severity level of notices displayed in the SQL shell. Accepted values include debug5, debug4, debug3, debug2, debug1, log, notice, warning, and error. notice Yes Yes
crdb_version The version of CockroachDB. CockroachDB OSS version No Yes
database The current database. Database in connection string, or empty if not specified. Yes Yes
datestyle The input string format for DATE and TIMESTAMP values. Accepted values include ISO,MDY, ISO,DMY, and ISO,YMD. The value set by the sql.defaults.datestyle cluster setting (ISO,MDY, by default). Yes Yes
default_int_size The size, in bytes, of an INT type. 8 Yes Yes
default_transaction_isolation All transactions execute with SERIALIZABLE isolation. See Transactions: Isolation levels. SERIALIZABLE No Yes
default_transaction_priority The default transaction priority for the current session. The supported options are low, normal, and high. normal Yes Yes
default_transaction_quality_of_service New in v22.1: The default transaction quality of service for the current session. The supported options are regular, critical, and background. See Set quality of service level. regular Yes Yes
default_transaction_read_only The default transaction access mode for the current session.
If set to on, only read operations are allowed in transactions in the current session; if set to off, both read and write operations are allowed. See SET TRANSACTION for more details.
off Yes Yes
default_transaction_use_follower_reads If set to on, all read-only transactions use AS OF SYSTEM TIME follower_read_timestamp() to allow the transaction to use follower reads.
If set to off, read-only transactions will only use follower reads if an AS OF SYSTEM TIME clause is specified in the statement, with an interval of at least 4.8 seconds.
off Yes Yes
disallow_full_table_scans If set to on, all queries that have planned a full table or full secondary index scan will return an error message. This setting does not apply to internal queries, which may plan full table or index scans without checking the session variable. off Yes Yes
distsql The query distribution mode for the session. By default, CockroachDB determines which queries are faster to execute if distributed across multiple nodes, and all other queries are run through the gateway node. auto Yes Yes
enable_implicit_select_for_update Indicates whether UPDATE and UPSERT statements acquire locks using the FOR UPDATE locking mode during their initial row scan, which improves performance for contended workloads.

For more information about how FOR UPDATE locking works, see the documentation for SELECT FOR UPDATE.
on Yes Yes
enable_insert_fast_path Indicates whether CockroachDB will use a specialized execution operator for inserting into a table. We recommend leaving this setting on. on Yes Yes
enable_zigzag_join Indicates whether the cost-based optimizer will plan certain queries using a zig-zag merge join algorithm, which searches for the desired intersection by jumping back and forth between the indexes based on the fact that after constraining indexes, they share an ordering. on Yes Yes
extra_float_digits The number of digits displayed for floating-point values. Only values between -15 and 3 are supported. 0 Yes Yes
force_savepoint_restart When set to true, allows the SAVEPOINT statement to accept any name for a savepoint. off Yes Yes
foreign_key_cascades_limit Limits the number of cascading operations that run as part of a single query. 10000 Yes Yes
idle_in_session_timeout Automatically terminates sessions that idle past the specified threshold.

When set to 0, the session will not timeout.
The value set by the sql.defaults.idle_in_session_timeout cluster setting (0s, by default). Yes Yes
idle_in_transaction_session_timeout Automatically terminates sessions that are idle in a transaction past the specified threshold.

When set to 0, the session will not timeout.
The value set by the sql.defaults.idle_in_transaction_session_timeout cluster setting (0s, by default). Yes Yes
index_recommendations_enabled New in v22.1: If true, display recommendations to create indexes required to eliminate full table scans.
For more details, see Default statement plans.
true Yes Yes
inject_retry_errors_enabled New in v22.1: If true, any statement executed inside of an explicit transaction (with the exception of SET statements) will return a transaction retry error. If the client retries the transaction using the special cockroach_restart SAVEPOINT name, after the 3rd retry error, the transaction will proceed as normal. Otherwise, the errors will continue until inject_retry_errors_enabled is set to false. For more details, see Testing transaction retry logic. false Yes Yes
intervalstyle The input string format for INTERVAL values. Accepted values include postgres, iso_8601, and sql_standard. The value set by the sql.defaults.intervalstyle cluster setting (postgres, by default). Yes Yes
is_superuser If on or true, the current user is a member of the admin role. User-dependent No Yes
large_full_scan_rows Determines which tables are considered "large" such that disallow_full_table_scans rejects full table or index scans of "large" tables. The default value is 1000. To reject all full table or index scans, set to 0. User-dependent No Yes
locality The location of the node.

For more information, see Locality.
Node-dependent No Yes
lock_timeout The amount of time a query can spend acquiring or waiting for a single row-level lock.
In CockroachDB, unlike in PostgreSQL, non-locking reads wait for conflicting locks to be released. As a result, the lock_timeout configuration applies to writes, and to locking and non-locking reads in read-write and read-only transactions.
If lock_timeout = 0, queries do not timeout due to lock acquisitions.
The value set by the sql.defaults.lock_timeout cluster setting (0, by default) Yes Yes
node_id The ID of the node currently connected to.

This variable is particularly useful for verifying load balanced connections.
Node-dependent No Yes
null_ordered_last New in v22.1: Set the default ordering of NULLs. The default order is NULLs first for ascending order and NULLs last for descending order. false Yes Yes
optimizer_use_histograms If on, the optimizer uses collected histograms for cardinality estimation. on No Yes
optimizer_use_multicol_stats If on, the optimizer uses collected multi-column statistics for cardinality estimation. on No Yes
prefer_lookup_joins_for_fks If on, the optimizer prefers lookup joins to merge joins when performing foreign key checks. off Yes Yes
reorder_joins_limit Maximum number of joins that the optimizer will attempt to reorder when searching for an optimal query execution plan.

For more information, see Join reordering.
8 Yes Yes
results_buffer_size The default size of the buffer that accumulates results for a statement or a batch of statements before they are sent to the client.
This can also be set for all connections using the sql.defaults.results_buffer_size cluster setting. Note that auto-retries generally only happen while no results have been delivered to the client, so reducing this size can increase the number of retryable errors a client receives. On the other hand, increasing the buffer size can increase the delay until the client receives the first result row. Setting to 0 disables any buffering.
16384 Yes Yes
require_explicit_primary_keys If on, CockroachDB throws on error for all tables created without an explicit primary key defined. off Yes Yes
search_path A list of schemas that will be searched to resolve unqualified table or function names.
For more details, see SQL name resolution.
public Yes Yes
serial_normalization Specifies the default handling of SERIAL in table definitions. Valid options include 'rowid', 'virtual_sequence', sql_sequence, and sql_sequence_cached.
If set to 'virtual_sequence', the SERIAL type auto-creates a sequence for better compatibility with Hibernate sequences.
If set to sql_sequence_cached, the sql.defaults.serial_sequences_cache_size cluster setting can be used to control the number of values to cache in a user's session, with a default of 256.
'rowid' Yes Yes
server_version The version of PostgreSQL that CockroachDB emulates. Version-dependent No Yes
server_version_num The version of PostgreSQL that CockroachDB emulates. Version-dependent Yes Yes
session_id The ID of the current session. Session-dependent No Yes
session_user The user connected for the current session. User in connection string No Yes
sql_safe_updates If false, potentially unsafe SQL statements are allowed, including DROP of a non-empty database and all dependent objects, DELETE without a WHERE clause, UPDATE without a WHERE clause, and ALTER TABLE .. DROP COLUMN.
See Allow Potentially Unsafe SQL Statements for more details.
true for interactive sessions from the built-in SQL client,
false for sessions from other clients
Yes Yes
statement_timeout The amount of time a statement can run before being stopped.
This value can be an int (e.g., 10) and will be interpreted as milliseconds. It can also be an interval or string argument, where the string can be parsed as a valid interval (e.g., '4s').
A value of 0 turns it off.
The value set by the sql.defaults.statement_timeout cluster setting (0s, by default). Yes Yes
stub_catalog_tables If off, querying an unimplemented, empty pg_catalog table will result in an error, as is the case in v20.2 and earlier. If on, querying an unimplemented, empty pg_catalog table simply returns no rows. on Yes Yes
timezone The default time zone for the current session. This session variable was named "time zone" (with a space) in CockroachDB 1.x. It has been renamed for compatibility with PostgreSQL. UTC Yes Yes
tracing The trace recording state. off Yes
transaction_isolation All transactions execute with SERIALIZABLE isolation. See Transactions: Isolation levels. This session variable was called transaction isolation level (with spaces) in CockroachDB 1.x. It has been renamed for compatibility with PostgreSQL. SERIALIZABLE No Yes
transaction_priority The priority of the current transaction. See Transactions: Transaction priorities for more details. This session variable was called transaction priority (with a space) in CockroachDB 1.x. It has been renamed for compatibility with PostgreSQL. NORMAL Yes Yes
transaction_read_only The access mode of the current transaction. See SET TRANSACTION for more details. off Yes Yes
transaction_rows_read_err The limit for the number of rows read by a SQL transaction. If this value is exceeded the transaction will fail (or the event will be logged to SQL_INTERNAL_PERF for internal transactions). 0 Yes Yes
transaction_rows_read_log The threshold for the number of rows read by a SQL transaction. If this value is exceeded, the event will be logged to SQL_PERF (or SQL_INTERNAL_PERF for internal transactions). 0 Yes Yes
transaction_rows_written_err The limit for the number of rows written by a SQL transaction. If this value is exceeded the transaction will fail (or the event will be logged to SQL_INTERNAL_PERF for internal transactions). 0 Yes Yes
transaction_rows_written_log The threshold for the number of rows written by a SQL transaction. If this value is exceeded, the event will be logged to SQL_PERF (or SQL_INTERNAL_PERF for internal transactions). 0 Yes Yes
transaction_status The state of the current transaction. See Transactions for more details. This session variable was called transaction status (with a space) in CockroachDB 1.x. It has been renamed for compatibility with PostgreSQL. NoTxn No Yes
vectorize The vectorized execution engine mode. Options include on and off. For more details, see Configure vectorized execution for CockroachDB. on Yes Yes

The following session variables are exposed only for backwards compatibility with earlier CockroachDB releases and have no impact on how CockroachDB runs:

Variable name Initial value Modify with SET? View with SHOW?
backslash_quote safe_encoding No Yes
client_encoding UTF8 No Yes
default_tablespace No Yes
enable_drop_enum_value off Yes Yes
enable_seqscan on Yes Yes
escape_string_warning on No Yes
experimental_enable_hash_sharded_indexes off Yes Yes
integer_datetimes on No Yes
max_identifier_length 128 No Yes
max_index_keys 32 No Yes
row_security off No Yes
standard_conforming_strings on No Yes
server_encoding UTF8 Yes Yes
synchronize_seqscans on No Yes
synchronous_commit on Yes Yes

Special syntax cases

CockroachDB supports the following syntax cases, for compatibility with common SQL syntax patterns:

Syntax Equivalent to Notes
USE ... SET database = ... This is provided as convenience for users with a MySQL/MSSQL background.
SET NAMES ... SET client_encoding = ... This is provided for compatibility with PostgreSQL clients.
SET ROLE <role> SET role = <role> This is provided for compatibility with PostgreSQL clients.
RESET ROLE SET role = 'none'/SET role = current_user() This is provided for compatibility with PostgreSQL clients.
SET SCHEMA <name> SET search_path = <name> This is provided for better compatibility with PostgreSQL.
SET SESSION CHARACTERISTICS AS TRANSACTION ISOLATION LEVEL ... SET default_transaction_isolation = ... This is provided for compatibility with standard SQL.
SET TIME ZONE ... SET timezone = ... This is provided for compatibility with PostgreSQL clients.

Examples

Set simple variables

The following examples demonstrate how to use SET to configure the default database for the current session:

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SET application_name = movr_app;
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SHOW application_name;
  application_name
--------------------
  movr_app
(1 row)

Set variables to values containing spaces

The following demonstrates how to use quoting to use values containing spaces:

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SET application_name = "movr app";
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SHOW application_name;
  application_name
--------------------
  movr app
(1 row)

Set variables to a list of values

The following demonstrates how to assign a list of values:

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SET search_path = pg_catalog,public;
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SHOW search_path;
     search_path
----------------------
  pg_catalog, public
(1 row)

Reset a variable to its default value

Tip:

You can use RESET to reset a session variable as well.

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SHOW search_path;
     search_path
----------------------
  pg_catalog, public
(1 row)
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SET search_path = DEFAULT;
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SHOW search_path;
    search_path
-------------------
  "$user", public
(1 row)

Set a variable for the duration of a single transaction

To set a variable for the duration of a single transaction, use the SET LOCAL statement.

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SHOW application_name;
  application_name
--------------------
  movr app
(1 row)
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BEGIN;
SET LOCAL application_name = demo;
SHOW application_name;
  application_name
--------------------
  demo
(1 row)
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COMMIT;
SHOW application_name;
  application_name
--------------------
  movr app
(1 row)

Roll back session variables set for a transaction

You can roll back session variable settings to savepoints.

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SHOW timezone;
  timezone
------------
  UTC
(1 row)
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BEGIN;
SET timezone = '+3';
SAVEPOINT s1;
SHOW timezone;
  timezone
------------
  +3
(1 row)
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SET LOCAL timezone = '+1';
SHOW timezone;
  timezone
------------
  +1
(1 row)
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ROLLBACK TO SAVEPOINT s1;
SHOW timezone;
  timezone
------------
  +3
(1 row)
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COMMIT;
SHOW timezone;
  timezone
------------
  +3
(1 row)

Assume another role

To assume another role for the duration of a session, use SET ROLE <role>. SET ROLE <role> is equivalent to SET role = <role>.

Note:

To assume a new role, the current user must be a member of the admin role, or a member of the target role.

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SHOW role;
  role
--------
  root
(1 row)
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CREATE ROLE new_role;
SHOW ROLES;
  username | options | member_of
-----------+---------+------------
  admin    |         | {}
  new_role | NOLOGIN | {}
  root     |         | {admin}
(3 rows)
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SET ROLE new_role;
SHOW role;
    role
------------
  new_role
(1 row)

To reset the role of the current user, use a RESET statement. RESET ROLE is equivalent to SET role = 'none' and SET role = current_user().

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RESET ROLE;
SHOW role;
  role
--------
  root
(1 row)

To assume a role for the duration of a single transaction, use SET LOCAL ROLE.

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BEGIN;
SET LOCAL ROLE new_role;
SHOW role;
    role
------------
  new_role
(1 row)
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COMMIT;
SHOW role;
  role
--------
  root
(1 row)

SET TIME ZONE

Warning:

As a best practice, we recommend not using this setting and avoid setting a session time for your database. We instead recommend converting UTC values to the appropriate time zone on the client side.

You can control the default time zone for a session with SET TIME ZONE. This will apply an offset to all TIMESTAMPTZ/TIMESTAMP WITH TIME ZONE and TIMETZ/TIME WITH TIME ZONE values in the session. By default, CockroachDB uses UTC as the time zone for SET TIME ZONE offsets.

Parameters

The input passed to SET TIME ZONE indicates the time zone for the current session. This value can be a string representation of a local system-defined time zone (e.g., 'EST', 'America/New_York') or a positive or negative numeric offset from UTC (e.g., -7, +7, or UTC-7, UTC+7) or GMT (e.g., GMT-7, GMT+7). The numeric offset input can also be colon-delimited (e.g., -7:00, GMT+7:00).

When setting a time zone, note the following:

  • Timezone abbreviations are case-insensitive.

  • Timezone abbreviations must be part of the tz database, as recognized by the tzdata Golang package.

  • DEFAULT, LOCAL, or 0 sets the session time zone to UTC.

  • Only offsets specified by integers (e.g., -7, 7) use the ISO 8601 time offset (i.e., the offset input is parsed as hours east of UTC). If you explicitly specify UTC or GMT for the time zone offset (e.g., UTC-7,GMT+7), or if the numeric input is colon-delimited (e.g., -7:00, GMT+7:00), CockroachDB uses the POSIX time offset instead (i.e., hours west of the specified time zone). This means that specifying an offset of -7 (i.e., -7 east of UTC) is equivalent to specifying GMT+7 (i.e., 7 west of UTC).

Example: Set the default time zone via SET TIME ZONE

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> SET TIME ZONE 'EST'; -- same as SET "timezone" = 'EST'
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> SHOW TIME ZONE;
  timezone
+----------+
  EST
(1 row)
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> SET TIME ZONE DEFAULT; -- same as SET "timezone" = DEFAULT
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> SHOW TIME ZONE;
  timezone
+----------+
  UTC
(1 row)

SET TRACING

SET TRACING changes the trace recording state of the current session. A trace recording can be inspected with the SHOW TRACE FOR SESSION statement.

Value Description
off Trace recording is disabled.
cluster Trace recording is enabled; distributed traces are collected.
on Same as cluster.
kv Same as cluster except that "kv messages" are collected instead of regular trace messages. See SHOW TRACE FOR SESSION.
results Result rows and row counts are copied to the session trace. This must be specified in order for the output of a query to be printed in the session trace.

Example: SET tracing = kv, results;

Known Limitations

SET does not properly apply ROLLBACK within a transaction. For example, in the following transaction, showing the TIME ZONE variable does not return 2 as expected after the rollback:

SET TIME ZONE +2;
BEGIN;
SET TIME ZONE +3;
ROLLBACK;
SHOW TIME ZONE;
timezone
------------
3

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See also


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