On Mon, Apr 04, 2022 at 10:28:30AM +0900, Masahiko Sawada wrote: > On Sun, Apr 3, 2022 at 9:45 AM Noah Misch <n...@leadboat.com> wrote: > > On Sat, Apr 02, 2022 at 08:44:45PM +0900, Masahiko Sawada wrote: > > > On Sat, Apr 2, 2022 at 7:04 PM Amit Kapila <amit.kapil...@gmail.com> > > > wrote: > > > > On Sat, Apr 2, 2022 at 1:43 PM Noah Misch <n...@leadboat.com> wrote: > > > > > Some options: > > > > > - Move subskiplsn after subdbid, so it's always aligned anyway. I've > > > > > confirmed that this lets the test pass, in 44s.
> --- a/src/include/catalog/pg_subscription.h > +++ b/src/include/catalog/pg_subscription.h > @@ -54,6 +54,17 @@ CATALOG(pg_subscription,6100,SubscriptionRelationId) > BKI_SHARED_RELATION BKI_ROW > > Oid subdbid BKI_LOOKUP(pg_database); /* > Database the > > * subscription is in. */ > + > + /* > + * All changes finished at this LSN are skipped. > + * > + * Note that XLogRecPtr, pg_lsn in the catalog, is 8-byte alignment > + * (TYPALIGN_DOUBLE) and it does not match the alignment on some > platforms > + * such as AIX. Therefore subskiplsn needs to be placed here so it is > + * always aligned. I'm reading this comment as saying that TYPALIGN_DOUBLE is always 8 bytes, but the problem arises precisely because TYPALIGN_DOUBLE==4 on AIX. On most hosts, the C alignment of an XLogRecPtr is 8 bytes, and TYPALIGN_DOUBLE==8. On AIX, C alignment is still 8 bytes, but TYPALIGN_DOUBLE==4. The tuples on disk and in shared buffers use TYPALIGN_DOUBLE to decide how much padding to insert, and that amount of padding needs to match the C alignment padding. Placing the field here reduces the padding to zero, making that invariant hold trivially. > + */ > + XLogRecPtr subskiplsn; > + > NameData subname; /* Name of the subscription */ > > Oid subowner BKI_LOOKUP(pg_authid); /* Owner of the > subscription */ > @@ -71,9 +82,6 @@ CATALOG(pg_subscription,6100,SubscriptionRelationId) > BKI_SHARED_RELATION BKI_ROW > bool subdisableonerr; /* True if a worker error > should cause the > * > subscription to be disabled */ > > - XLogRecPtr subskiplsn; /* All changes finished at this > LSN are > - * skipped */ Some code sites list pg_subscription fields in field order. Please update them so they continue to list fields in field order. CreateSubscription() is one example.
