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MediaWiki settings: $wgDebugDBTransactions

Introduced in version: 1.20.0 (r113487)(git #cfb8e9a2)
Removed in version: 1.27.0 (git #a88df43d)
Allowed values: (boolean)
Default value: false
Other settings: Alphabetical | By function


This setting enables additional database transaction lifecycle tracing in the debug output:

Transaction state changed from IDLE -> TRANS

Whenever transaction status is changed

no database transaction is open
a transaction has been open
a transaction is in an error state

Example output:

Query trunk (15) (slave): BEGIN
Transaction state changed from IDLE -> TRANS
Query trunk (16) (slave): SELECT /* DatabasePostgres::schemaExists  */  1  
            FROM "pg_catalog"."pg_namespace"  WHERE nspname = 'mediawiki'  LIMIT 1  
Query trunk (17) (slave): SELECT /* DatabasePostgres::getSchemas  */ current_schemas(false)
Schema "mediawiki" already in the search path
Query trunk (18) (slave): COMMIT
Transaction state changed from TRANS -> IDLE

This feature is useful in troubleshooting situations where some operations seem to be ignored (phab:T37572) or whenever 25P02: ERROR: current transaction is aborted, commands ignored until end of transaction block error message is returned (phab:T39172) or where it is necessary to understand what was the transaction progress in case of deferred reference check failure (phab:T60189).

An end-to-end transaction logging may help to pinpoint situations where features like localization cache or deferred updates might interfere with the expected state of the transaction during mainline processing.

See also[edit]