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Correctly mark pg_subscription_rel.srsublsn as nullable. 

The code has always set this column to NULL when it's not valid,
but the catalog header's description failed to reflect that,
as did the SGML docs, as did some of the code.  To prevent future
coding errors of the same ilk, let's hide the field from C code
as though it were variable-length (which, in a sense, it is).

As with commit 72eab84a5, we can only fix this cleanly in HEAD
and v13; the problem extends further back but we'll need some
klugery in the released branches.

Discussion: https://postgr.es/m/367660.1595202498@sss.pgh.pa.us
This commit is contained in:
Tom Lane 2020-07-20 14:55:56 -04:00
parent 2f1f189cf8
commit e5372b48b9
4 changed files with 32 additions and 6 deletions
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4
doc/src/sgml/catalogs.sgml
View File

@ -7620,7 +7620,9 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
<structfield>srsublsn</structfield> <type>pg_lsn</type>
</para>
<para>
End LSN for <literal>s</literal> and <literal>r</literal> states.
Remote LSN of the state change used for synchronization coordination
when in <literal>s</literal> or <literal>r</literal> states,
otherwise null
</para></entry>
</row>
</tbody>

18
src/backend/catalog/pg_subscription.c
View File

@ -451,13 +451,20 @@ GetSubscriptionRelations(Oid subid)
{
Form_pg_subscription_rel subrel;
SubscriptionRelState *relstate;
Datum d;
bool isnull;
subrel = (Form_pg_subscription_rel) GETSTRUCT(tup);
relstate = (SubscriptionRelState *) palloc(sizeof(SubscriptionRelState));
relstate->relid = subrel->srrelid;
relstate->state = subrel->srsubstate;
relstate->lsn = subrel->srsublsn;
d = SysCacheGetAttr(SUBSCRIPTIONRELMAP, tup,
Anum_pg_subscription_rel_srsublsn, &isnull);
if (isnull)
relstate->lsn = InvalidXLogRecPtr;
else
relstate->lsn = DatumGetLSN(d);
res = lappend(res, relstate);
}
@ -503,13 +510,20 @@ GetSubscriptionNotReadyRelations(Oid subid)
{
Form_pg_subscription_rel subrel;
SubscriptionRelState *relstate;
Datum d;
bool isnull;
subrel = (Form_pg_subscription_rel) GETSTRUCT(tup);
relstate = (SubscriptionRelState *) palloc(sizeof(SubscriptionRelState));
relstate->relid = subrel->srrelid;
relstate->state = subrel->srsubstate;
relstate->lsn = subrel->srsublsn;
d = SysCacheGetAttr(SUBSCRIPTIONRELMAP, tup,
Anum_pg_subscription_rel_srsublsn, &isnull);
if (isnull)
relstate->lsn = InvalidXLogRecPtr;
else
relstate->lsn = DatumGetLSN(d);
res = lappend(res, relstate);
}

2
src/include/catalog/catversion.h
View File

@ -53,6 +53,6 @@
*/
/* yyyymmddN */
#define CATALOG_VERSION_NO 202007191
#define CATALOG_VERSION_NO 202007201
#endif

14
src/include/catalog/pg_subscription_rel.h
View File

@ -33,8 +33,18 @@ CATALOG(pg_subscription_rel,6102,SubscriptionRelRelationId)
Oid srsubid; /* Oid of subscription */
Oid srrelid; /* Oid of relation */
char srsubstate; /* state of the relation in subscription */
XLogRecPtr srsublsn; /* remote lsn of the state change used for
* synchronization coordination */
/*
* Although srsublsn is a fixed-width type, it is allowed to be NULL, so
* we prevent direct C code access to it just as for a varlena field.
*/
#ifdef CATALOG_VARLEN /* variable-length fields start here */
XLogRecPtr srsublsn BKI_FORCE_NULL; /* remote LSN of the state change
* used for synchronization
* coordination, or NULL if not
* valid */
#endif
} FormData_pg_subscription_rel;
typedef FormData_pg_subscription_rel *Form_pg_subscription_rel;