Re: Logical Replication of sequences

Hi Vignesh.

I had a quick look at this patch.

======

- * Instead, we invalidate only the relsyncache.
+ * Instead, invalidate the relation sync cache for publications that
+ * include tables. Invalidation is not required for sequences only
+ * publications.
  */
- InvalidatePubRelSyncCache(pub->oid, pub->puballtables);
+ if (!pub->puballsequences || pub->puballtables)
+ InvalidatePubRelSyncCache(pub->oid, pub->puballtables);

I felt all these "sequence only" conditions are becoming difficult to read.

It wonder if it would be better to introduce some function like:

bool
PubHasSequencesOnly(pub)
{
  return pub->puballsequences && !pub->puballtables;
}

IIUC the current patch code only works because publication syntax like
below is not yet supported:

CREATE PUBLICATION pub1 FOR ALL SEQUENCES, TABLE t1;

But when that syntax does become possible, then all these conditions
will be broken.

Should we prepare for that eventuality by introducing some function
right now, so as to contain all the future broken code?

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Kind Regards,
Peter Smith.
Fujitsu Australia