Re: [BUG] Logical replication failure "ERROR: could not map filenode "base/13237/442428" to relation OID" with catalog modifying txns

On Mon, May 30, 2022 at 11:13 AM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>
> I've attached three POC patches:
>

I think it will be a good idea if you can add a short commit message
at least to say which patch is proposed for HEAD and which one is for
back branches. Also, it would be good if you can add some description
of the fix in the commit message. Let's remove poc* from the patch
name.

Review poc_add_running_catchanges_xacts_to_serialized_snapshot
=====================================================
1.
+ /*
+ * Array of transactions that were running when the snapshot serialization
+ * and changed system catalogs,

The part of the sentence after serialization is not very clear.

2.
- if (ReorderBufferXidHasCatalogChanges(builder->reorder, subxid))
+ if (ReorderBufferXidHasCatalogChanges(builder->reorder, subxid) ||
+ bsearch(&xid, builder->catchanges.xip, builder->catchanges.xcnt,
+ sizeof(TransactionId), xidComparator) != NULL)

Why are you using xid instead of subxid in bsearch call? Can we add a
comment to say why it is okay to use xid if there is a valid reason?
But note, we are using subxid to add to the committed xact array so
not sure if this is a good idea but I might be missing something.

Suggestions for improvement in comments:
- /*
- * Update the transactions that are running and changes
catalogs that are
- * not committed.
- */
+ /* Update the catalog modifying transactions that are yet not
committed. */
if (builder->catchanges.xip)
pfree(builder->catchanges.xip);
builder->catchanges.xip =
ReorderBufferGetCatalogChangesXacts(builder->reorder,
@@ -1647,7 +1644,7 @@ SnapBuildSerialize(SnapBuild *builder, XLogRecPtr lsn)
COMP_CRC32C(ondisk->checksum, ondisk_c, sz);
ondisk_c += sz;

- /* copy catalog-changes xacts */
+ /* copy catalog modifying xacts */
sz = sizeof(TransactionId) * builder->catchanges.xcnt;
memcpy(ondisk_c, builder->catchanges.xip, sz);
COMP_CRC32C(ondisk->checksum, ondisk_c, sz);

--
With Regards,
Amit Kapila.