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Coordinator DB
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SET ​

SET saves a database setting and applies it to connected clients before later requests. A database must be selected first.

Database management changes require autocommit and no active transactions in the selected database. Resource limits are sampled once per request, so a SET within a batch changes defaults for later requests.

Values are validated before they are persisted. Configured server XML ceilings still limit the effective setting; inspect system.settings or SHOW SETTINGS to see the effective values.

Syntax ​

text
SET setting_name = value

Supported names ​

  • log_queries
  • log_queries_min_query_duration_ms
  • max_execution_time
  • max_memory_usage
  • max_result_rows
  • max_response_bytes
  • max_threads

The four connection/header settings use PRAGMA or validated system.settings writes instead. Consult the database settings reference for types, units and defaults.

Example ​

Enabling query logging ​

sql
SET log_queries = 1;
sql
SELECT name, value
FROM system.settings
WHERE name = 'log_queries'
FORMAT csv;
text
"log_queries","1"

SET and SETTINGS ​

SET persists a database setting. A statement SETTINGS clause configures data-format options for one statement and does not persist them. Format options such as csv_separator are not accepted as database SET names.

See format settings for those statement options.