> ## Documentation Index
> Fetch the complete documentation index at: https://cockroachlabs.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.
# Session Variables
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The `SET` statement can modify one of the session configuration variables. These can also be queried via `SHOW`.
## 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 | |
| `autocommit\_before\_ddl` | When the `autocommit\_before\_ddl` session setting is set to `on`, any schema change statement that is sent during an explicit transaction will cause the transaction to commit before executing the schema change. | `off` | 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 | |
| `copy\_from\_atomic\_enabled` | If set to `on`, `COPY FROM` statements are committed atomically, matching PostgreSQL behavior. If set to `off`, `COPY FROM` statements are segmented into batches of 100 rows unless issued within an explicit transaction, matching the CockroachDB behavior in versions prior to v22.2. | `on` | Yes | Yes | |
| `copy\_transaction\_quality\_of\_service` | The default quality of service for `COPY` statements in the current session. The supported options are `regular`, `critical`, and `background`. See Set quality of service level. | `background` | Yes | Yes | |
| `cost\_scans\_with\_default\_col\_size` | Whether to prevent the optimizer from considering column size when costing plans. | `false` | 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\_text\_search\_config` | The dictionary used to normalize tokens and eliminate stop words when calling a full-text search function without a configuration parameter. See Full-Text Search. | `english` | Yes | Yes | |
| `default\_transaction\_isolation` | The isolation level at which transactions in the session execute (`SERIALIZABLE` or `READ COMMITTED`). See Isolation levels. | `SERIALIZABLE` | Yes | 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` | 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 | |
| `disable\_changefeed\_replication` | When `true`, changefeeds will not emit messages for any changes (e.g., `INSERT`, `UPDATE`) issued to watched tables during that session. | `false` | Yes | Yes | |
| `disallow\_full\_table\_scans` | If set to `on`, queries on "large" tables with a row count greater than [`large\_full\_scan\_rows`](#large-full-scan-rows) will not use full table or index scans. If no other query plan is possible, queries 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 | |
| `enable\_auto\_rehoming` | When enabled, the home regions of rows in `REGIONAL BY ROW` tables are automatically set to the region of the gateway node from which any `UPDATE` or `UPSERT` statements that operate on those rows originate. | `off` | Yes | Yes | |
| `enable\_create\_stats\_using\_extremes` | If `on`, allows manual creation of partial statistics using the `CREATE STATISTICS ... USING EXTREMES` syntax. | `on` | Yes | Yes | |
| `enable\_durable\_locking\_for\_serializable` | Indicates whether CockroachDB replicates `FOR UPDATE` and `FOR SHARE` locks via Raft, allowing locks to be preserved when leases are transferred. Note that replicating `FOR UPDATE` and `FOR SHARE` locks will add latency to those statements. This setting only affects `SERIALIZABLE` transactions and matches the default `READ COMMITTED` behavior when enabled. | `off` | Yes | Yes | |
| `enable\_experimental\_alter\_column\_type\_general` | If `on`, it is possible to alter column data types. | `off` | Yes | Yes | |
| `enable\_implicit\_fk\_locking\_for\_serializable` | Indicates whether CockroachDB uses shared locks to perform foreign key checks. To take effect, the [`enable\_shared\_locking\_for\_serializable`](#enable-shared-locking-for-serializable) setting must also be enabled. This setting only affects `SERIALIZABLE` transactions and matches the default `READ COMMITTED` behavior when enabled. | `off` | 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\_implicit\_transaction\_for\_batch\_statements` | Indicates whether multiple statements in a single query (a "batch statement") will all run in the same implicit transaction, which matches the PostgreSQL wire protocol. | `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\_shared\_locking\_for\_serializable` | Indicates whether shared locks are enabled for `SERIALIZABLE` transactions. When `off`, `SELECT` statements using `FOR SHARE` are still permitted under `SERIALIZABLE` isolation, but silently do not lock. | `off` | Yes | Yes | |
| `enable\_super\_regions` | When enabled, you can define a super region: a set of database regions on a multi-region cluster such that your schema objects will have all of their replicas stored *only* in regions that are members of the super region. | `off` | Yes | Yes | |
| `enable\_zigzag\_join` | Indicates whether the cost-based optimizer will plan certain queries using a zigzag 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 | |
| `enforce\_home\_region` | If set to `on`, queries return an error and in some cases a suggested resolution if they cannot run entirely in their home region. This can occur if a query has no home region (for example, if it reads from different home regions in a regional by row table) or a query's home region differs from the gateway region. Note that only tables with `ZONE`survivability can be scanned without error when this is enabled. For more information about home regions, see Table localities. This feature is in preview. It is subject to change. | `off` | Yes | Yes | |
| `enforce\_home\_region\_follower\_reads\_enabled` | If `on` while the `enforce\_home\_region` setting is `on`, allows `enforce\_home\_region` to perform `AS OF SYSTEM TIME`follower reads to detect and report a query's home region, if any. This feature is in preview. It is subject to change. | `off` | Yes | Yes | |
| `expect\_and\_ignore\_not\_visible\_columns\_in\_copy` | If `on`, `COPY FROM` with no column specifiers will assume that hidden columns are in the copy data, but will ignore them when applying `COPY FROM`. | `off` | 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` | 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` | 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 Test 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 `0`, which disallows all full table or index scans. | User-dependent | No | Yes | |
| `legacy\_varchar\_typing` | **New in v24.3.2:** If `on`, type checking and overload resolution for `VARCHAR` types ignore overloads that cause errors, allowing comparisons between `VARCHAR` and non-`STRING`-like placeholder values to execute successfully. If `off`, type checking of these comparisons is more strict and must be handled with explicit type casts. | `on` | Yes | 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 | |
| `multiple\_active\_portals\_enabled` | Whether to enable the multiple active portals pgwire feature. | `false` | 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` | Set the default ordering of `NULL`s. The default order is `NULL`s first for ascending order and `NULL`s last for descending order. | `false` | Yes | Yes | |
| `optimizer\_merge\_joins\_enabled` | If `on`, the optimizer will explore query plans with merge joins. | `on` | Yes | Yes | |
| `optimizer\_push\_offset\_into\_index\_join` | If `on`, the optimizer will attempt to push offset expressions into index join expressions to produce more efficient query plans. | `on` | Yes | Yes | |
| `optimizer\_use\_forecasts` | If `on`, the optimizer uses forecasted statistics for query planning. | `on` | Yes | Yes | |
| `optimizer\_use\_histograms` | If `on`, the optimizer uses collected histograms for cardinality estimation. | `on` | No | Yes | |
| `optimizer\_use\_improved\_multi\_column\_selectivity\_estimate` | If `on`, the optimizer uses an improved selectivity estimate for multi-column predicates. | `on` | Yes | Yes | |
| `optimizer\_use\_improved\_zigzag\_join\_costing` | If `on`, the cost of zigzag joins is updated so they will be never be chosen over scans unless they produce fewer rows. To take effect, the [`enable\_zigzag\_join`](#enable-zigzag-join) setting must also be enabled. | `on` | Yes | Yes | |
| `optimizer\_use\_lock\_op\_for\_serializable` | If `on`, the optimizer uses a `Lock` operator to construct query plans for `SELECT` statements using the `FOR UPDATE` and `FOR SHARE` clauses. This setting only affects `SERIALIZABLE` transactions. `READ COMMITTED` transactions are evaluated with the `Lock` operator regardless of the setting. | `off` | Yes | Yes | |
| `optimizer\_use\_merged\_partial\_statistics` | If `on`, the optimizer uses partial statistics merged with existing full table statistics for cardinality estimation. | `off` | Yes | Yes | |
| `optimizer\_use\_multicol\_stats` | If `on`, the optimizer uses collected multi-column statistics for cardinality estimation. | `on` | No | Yes | |
| `optimizer\_use\_not\_visible\_indexes` | If `on`, the optimizer uses not visible indexes for planning. | `off` | No | Yes | |
| `optimizer\_use\_virtual\_computed\_column\_stats` | If `on`, the optimizer uses table statistics on virtual computed columns. | `on` | Yes | Yes | |
| `plan\_cache\_mode` | The type of plan that is cached in the query plan cache: `auto`, `force\_generic\_plan`, or `force\_custom\_plan`. For more information, refer to Query plan type. | `force\_custom\_plan` | Yes | Yes | |
| `plpgsql\_use\_strict\_into` | If `on`, PL/pgSQL `SELECT ... INTO` and `RETURNING ... INTO` statements behave as though the `STRICT` option is specified. This causes the SQL statement to error if it does not return exactly one row. | `off` | Yes | Yes | |
| `pg\_trgm.similarity\_threshold` | The threshold above which a `%` string comparison returns `true`. The value must be between `0` and `1`. For more information, see Trigram Indexes. | `0.3` | Yes | 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 | |
| `require\_explicit\_primary\_keys` | If `on`, CockroachDB throws an 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`, `sql\_sequence\_cached`, `sql\_sequence\_cached\_node`, and `unordered\_rowid`. If set to `'virtual\_sequence'`, the `SERIAL` type auto-creates a sequence for [better compatibility with Hibernate sequences](https://forum.cockroachlabs.com/t/hibernate-sequence-generator-returns-negative-number-and-ignore-unique-rowid/1885). If set to `sql\_sequence\_cached` or `sql\_sequence\_cached\_node`, you can use the `sql.defaults.serial\_sequences\_cache\_size`cluster setting to control the number of values to cache in a user's session, with a default of 256. If set to `unordered\_rowid`, the `SERIAL` type generates a globally unique 64-bit integer (a combination of the insert timestamp and the ID of the node executing the statement) that does not have unique ordering. | `'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 `true`, the following potentially unsafe SQL statements are disallowed: `DROP DATABASE` of a non-empty database and all dependent objects; `DELETE` and `UPDATE` without a `WHERE` clause, unless a `LIMIT` clause is included; `SELECT ... FOR UPDATE` and `SELECT ... FOR SHARE` without a `WHERE` or `LIMIT` clause; `ALTER TABLE ... DROP COLUMN`; and converting an existing table to `REGIONAL BY ROW` using `ALTER TABLE ... LOCALITY`, unless a region column has already been added to the table. For more details, refer to Allow potentially unsafe SQL statements. | `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. | `UTC` | Yes | Yes |
| | `tracing` | The trace recording state. | `off` | Yes | Yes |
| `transaction\_isolation` | The isolation level at which the transaction executes (`SERIALIZABLE` or `READ COMMITTED`). See Isolation levels. | `SERIALIZABLE` | Yes | 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. | `NoTxn` | No | Yes | |
| `transaction\_timeout` | Aborts an explicit transaction when it runs longer than the configured duration. Stored in milliseconds; can be expressed in milliseconds or as an `INTERVAL`. | `0` | Yes | Yes | |
| `troubleshooting\_mode\_enabled` | When enabled, avoid performing additional work on queries, such as collecting and emitting telemetry data. This session variable is particularly useful when the cluster is experiencing issues, unavailability, or failure. | `off` | Yes | Yes | |
| `use\_declarative\_schema\_changer` | Whether to use the declarative schema changer for supported statements. | `on` | Yes | Yes | |
| | `vectorize` | The vectorized execution engine mode. Options include `on` and `off`. For more details, see Configure vectorized execution for CockroachDB. | `on` | Yes | Yes |
| `virtual\_cluster\_name` | The name of the virtual cluster that the SQL client is connected to. | Session-dependent | No | 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 |
## Considerations
### Session variable precedence
When a session starts, CockroachDB determines the initial value of each session variable by evaluating the settings in the following order (items earlier in the list take precedence over later items):
1. Connection string parameters: A value supplied as a query parameter in the connection URL (for example, `.../movr?sslmode=disable&timezone=UTC` ).
2. Per-role, per-database defaults: A value set by `ALTER ROLE {role_name} IN DATABASE {db_name} SET {var}={value}`.
3. Per-role, all-database defaults: A value set by `ALTER ROLE {role_name} SET {var}={value}`.
4. All-role, per-database defaults: A value set by `ALTER ROLE ALL IN DATABASE {db_name} SET {var}={value}` or equivalently by `ALTER DATABASE {db_name} SET {var}={value}`.
5. Cluster-wide defaults for all roles and all databases: A value set by `ALTER ROLE ALL SET {var}={value}`.
If a session variable is not modified using any of the preceding methods, the built-in system default value is used. Note that the `root` user is exempt from settings 3–5. The `root` user is only affected by values specified in the connection string.
You can also set session variables for the duration of a single transaction by using `SET LOCAL {var}={value}`.
Changes to defaults using the preceding methods only apply to **future** sessions. This is because session variable resolution happens at session start time. To change a default value in an existing open session, set the variable explicitly with `SET`.
## See also
* `SET session variable`
* `SET TRANSACTION`
* `SET CLUSTER SETTING`
* `SHOW session variable`
* The `TIMESTAMP` and `TIMESTAMPTZ` data types.
* `SHOW TRACE FOR SESSION`
* `pg_catalog`
* `SHOW DEFAULT SESSION VARIABLES FOR ROLE`