ALLOWNULLABLEKEYS | NOALLOWNULLABLEKEYS

Valid For

GLOBALS

ALLOWNULLABLEKEYS is not valid for integrated Replicat.

Description

Use NOALLOWNULLABLEKEYS to change the key selection logic so that it does not consider a nullable unique key as a viable candidate for uniquely identifying a row. When disabled, the nullable unique keys are viable candidates. The default value for NOALLOWNULLABLEKEYS is set to true.

Allowing Oracle GoldenGate to use a nullable key can cause data corruption, as Oracle treats each row with a NULL value as a key column and as a separate unique value. It is recommended to use NOALLOWNULLABLEKEYS unless you are absolutely sure that the key column does not contain any NULL values.

Be careful when using this parameter because it impacts the contents of the trail file and all installations must be in sync when using this parameter.

Upon upgrade to Oracle GoldenGate 19c, it is recommended that you query DBA_LOGSTDBY_NOT_UNIQUE view. If SCHEMATRANDATA is not being used, then for each table in DBA_LOGSTDBY_NOT_UNIQUE view, add KEYCOLS that mirror key columns returned by INFO TRANDATA, DELETE TRANDATA, or ADD TRANDATA for table to select or use a key with non-NULL columns.

Default

NOALLOWNULLABLEKEYS

Syntax

ALLOWNULLABLEKEYS | NOALLOWNULLABLEKEYS