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-rw-r--r--src/backend/commands/vacuum.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index e154507ecd0..4b67b40b285 100644
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -893,6 +893,7 @@ vacuum_set_xid_limits(Relation rel,
int effective_multixact_freeze_max_age;
TransactionId limit;
TransactionId safeLimit;
+ MultiXactId oldestMxact;
MultiXactId mxactLimit;
MultiXactId safeMxactLimit;
@@ -970,7 +971,8 @@ 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;
@@ -984,7 +986,11 @@ 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;