1.8 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
Parent topic: Oracle GoldenGate Parameters