SET (storage parameter)

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The SET (storage parameter) statement sets a storage parameter on an existing table.

Note:

The SET (storage parameter) is a subcommand of ALTER TABLE.

To set a storage parameter on an existing index, you must drop and recreate the index with the storage parameter.

Syntax

alter_table_set_storage_param ::=

ALTER TABLE IF EXISTS table_name SET ( storage_parameter_key = var_value )

Command parameters

Parameter Description
table The table to which you are setting the parameter.
parameter_name The name of the storage parameter. See Storage parameters for a list of available parameters.

Storage parameters

Table parameters

Parameter name Description Data type Default value
exclude_data_from_backup New in v22.1: Excludes the data in this table from any future backups. Boolean false
ttl Signifies if a TTL is active. Automatically set and controls the reset of all TTL-related storage parameters. N/A N/A
ttl_automatic_column If set, use the value of the crdb_internal_expiration hidden column. Always set to true and cannot be reset. Boolean true
ttl_delete_batch_size The number of rows to delete at a time. Minimum: 1. Integer 100
ttl_delete_rate_limit The maximum number of rows to be deleted per second (rate limit). 0 means no limit. Integer 0
ttl_expire_after The interval when a TTL will expire. This parameter is required to enable TTL. Minimum: '1 microsecond'.

Use RESET (ttl) to remove from the table.
Interval N/A
ttl_job_cron The frequency at which the TTL job runs. CRON syntax '@hourly'
ttl_label_metrics Whether or not TTL metrics are labelled by table name (at the risk of added cardinality). Boolean false
ttl_pause If set, stops the TTL job from executing. Boolean false
ttl_range_concurrency The Row-Level TTL queries split up scans by ranges, and this determines how many concurrent ranges are processed at a time. Minimum: 1. Integer 1
ttl_row_stats_poll_interval If set, counts rows and expired rows on the table to report as Prometheus metrics while the TTL job is running. Unset by default, meaning no stats are fetched and reported. Interval N/A
ttl_select_batch_size The number of rows to select at one time during the row expiration check. Minimum: 1. Integer 500

The following parameters are included for PostgreSQL compatibility and do not affect how CockroachDB runs:

  • autovacuum_enabled
  • fillfactor

Required privileges

The user must be a member of the admin or owner roles, or have the CREATE privilege on the table.

Examples

Exclude a table's data from backups

New in v22.1: In some situations, you may want to exclude a table's row data from a backup. For example, you have a table that contains high-churn data that you would like to garbage collect more quickly than the incremental backup schedule for the database or cluster holding the table. You can use the exclude_data_from_backup = true parameter with a CREATE TABLE or ALTER TABLE statement to mark a table's row data for exclusion from a backup.

For more detail and an example through the backup and restore process using this parameter, see Take Full and Incremental Backups.

To set the exclude_data_from_backup parameter for a table, run the following:

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ALTER TABLE movr.user_promo_codes SET (exclude_data_from_backup = true);

The CREATE statement for this table will now show the parameter set:

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SHOW CREATE user_promo_codes;
table_name         |                                                create_statement
-------------------+------------------------------------------------------------------------------------------------------------------
user_promo_codes   | CREATE TABLE public.user_promo_codes (
                   |     city VARCHAR NOT NULL,
                   |     user_id UUID NOT NULL,
                   |     code VARCHAR NOT NULL,
                   |     "timestamp" TIMESTAMP NULL,
                   |     usage_count INT8 NULL,
                   |     CONSTRAINT user_promo_codes_pkey PRIMARY KEY (city ASC, user_id ASC, code ASC),
                   |     CONSTRAINT user_promo_codes_city_user_id_fkey FOREIGN KEY (city, user_id) REFERENCES public.users(city, id)
                   | ) WITH (exclude_data_from_backup = true)
(1 row)

Backups will no longer include the data within the user_promo_codes table. The table will still be present in the backup, but it will be empty.

To remove this parameter from a table, run:

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ALTER TABLE movr.user_promo_codes SET (exclude_data_from_backup = false);

This will ensure that the table's data is stored in subsequent backups that you take.

See also


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