Fix volatility marking of commit timestamp functions

alvherre · alvherre · commit e8e86fbc8b36 · 2015-07-30T15:19:49.000-03:00
They are marked stable, but since they act on instantaneous state and it
is possible to consult state of transactions as they commit, the results
could change mid-query.  They need to be marked volatile, and this
commit does so.

There would normally be a catversion bump here, but this is so much a
niche feature and I don't believe there's real damage from the incorrect
marking, that I refrained.

Backpatch to 9.5, where commit timestamps where introduced.

Per note from Fujii Masao.
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
@@ -3082,10 +3082,10 @@ DESCR("view two-phase transactions");
 DATA(insert OID = 3819 (  pg_get_multixact_members PGNSP PGUID 12 1 1000 0 0 f f f f t t v 1 0 2249 "28" "{28,28,25}" "{i,o,o}" "{multixid,xid,mode}" _null_ _null_ pg_get_multixact_members _null_ _null_ _null_ ));
 DESCR("view members of a multixactid");
 
-DATA(insert OID = 3581 ( pg_xact_commit_timestamp PGNSP PGUID 12 1 0 0 0 f f f f t f s 1 0 1184 "28" _null_ _null_ _null_ _null_ _null_ pg_xact_commit_timestamp _null_ _null_ _null_ ));
+DATA(insert OID = 3581 ( pg_xact_commit_timestamp PGNSP PGUID 12 1 0 0 0 f f f f t f v 1 0 1184 "28" _null_ _null_ _null_ _null_ _null_ pg_xact_commit_timestamp _null_ _null_ _null_ ));
 DESCR("get commit timestamp of a transaction");
 
-DATA(insert OID = 3583 ( pg_last_committed_xact PGNSP PGUID 12 1 0 0 0 f f f f t f s 0 0 2249 "" "{28,1184}" "{o,o}" "{xid,timestamp}" _null_ _null_ pg_last_committed_xact _null_ _null_ _null_ ));
+DATA(insert OID = 3583 ( pg_last_committed_xact PGNSP PGUID 12 1 0 0 0 f f f f t f v 0 0 2249 "" "{28,1184}" "{o,o}" "{xid,timestamp}" _null_ _null_ pg_last_committed_xact _null_ _null_ _null_ ));
 DESCR("get transaction Id and commit timestamp of latest transaction commit");
 
 DATA(insert OID = 3537 (  pg_describe_object		PGNSP PGUID 12 1 0 0 0 f f f f t f s 3 0 25 "26 26 23" _null_ _null_ _null_ _null_ _null_ pg_describe_object _null_ _null_ _null_ ));
