Re: Confused comment about drop replica identity index

On 2021-Dec-15, Michael Paquier wrote:

> On Tue, Dec 14, 2021 at 07:10:49PM +0530, Ashutosh Bapat wrote:
> > This code in RelationGetIndexList() is not according to that comment.
> > 
> >    if (replident == REPLICA_IDENTITY_DEFAULT && OidIsValid(pkeyIndex))
> >         relation->rd_replidindex = pkeyIndex;
> >     else if (replident == REPLICA_IDENTITY_INDEX && OidIsValid(candidateIndex))
> >         relation->rd_replidindex = candidateIndex;
> >     else
> >         relation->rd_replidindex = InvalidOid;
> 
> Yeah, the comment is wrong.  If the index of a REPLICA_IDENTITY_INDEX
> is dropped, I recall that the behavior is the same as
> REPLICA_IDENTITY_NOTHING.

Hmm, so if a table has REPLICA IDENTITY INDEX and there is a publication
with an explicit column list, then we need to forbid the DROP INDEX for
that index.

I wonder why don't we just forbid DROP INDEX of an index that's been
defined as replica identity.  It seems quite silly an operation to
allow.

-- 
Álvaro Herrera           39°49'30"S 73°17'W  —  https://www.EnterpriseDB.com/
"Ed is the standard text editor."
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