Dear Kenny,
> Right, CREATE_REPLICATION_SLOT always returns exactly 4 columns, so != 4 is
> more accurate. v3 attached uses != 4 and drops "or more" from the errdetail.
Basically LGTM. From my perspective the code comment might be too detail:
"CREATE_REPLICATION_SLOT has always returned a single row with four columns"
might be enough. But it's not the strong opinion - let's confirm the Fujii-san's idea.
Best regards,
Hayato Kuroda
FUJITSU LIMITED