diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c index 44d500eab5579d40131c4d5b83fbf20c6f82c108..ebc76eaa2079d1d8111ce3ab12b53916c3a35a1b 100644 --- a/src/backend/commands/vacuum.c +++ b/src/backend/commands/vacuum.c @@ -477,6 +477,7 @@ vacuum_set_xid_limits(Relation rel, int effective_multixact_freeze_max_age; TransactionId limit; TransactionId safeLimit; + MultiXactId oldestMxact; MultiXactId mxactLimit; MultiXactId safeMxactLimit; @@ -552,7 +553,8 @@ vacuum_set_xid_limits(Relation rel, Assert(mxid_freezemin >= 0); /* compute the cutoff multi, being careful to generate a valid value */ - mxactLimit = GetOldestMultiXactId() - mxid_freezemin; + oldestMxact = GetOldestMultiXactId(); + mxactLimit = oldestMxact - mxid_freezemin; if (mxactLimit < FirstMultiXactId) mxactLimit = FirstMultiXactId; @@ -566,7 +568,11 @@ vacuum_set_xid_limits(Relation rel, ereport(WARNING, (errmsg("oldest multixact is far in the past"), errhint("Close open transactions with multixacts soon to avoid wraparound problems."))); - mxactLimit = safeMxactLimit; + /* Use the safe limit, unless an older mxact is still running */ + if (MultiXactIdPrecedes(oldestMxact, safeMxactLimit)) + mxactLimit = oldestMxact; + else + mxactLimit = safeMxactLimit; } *multiXactCutoff = mxactLimit;