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| author | Robert Haas | 2015-05-07 15:00:47 +0000 |
|---|---|---|
| committer | Robert Haas | 2015-05-07 15:19:31 +0000 |
| commit | 7be47c56af3d3013955c91c2877c08f2a0e3e6a2 (patch) | |
| tree | 80847057d957048de9e70b92fc196465a34f26f8 | |
| parent | 82ec7c95b701d18530eb4eed923a305a0d82bdaf (diff) | |
Fix incorrect math in DetermineSafeOldestOffset.
The old formula didn't have enough parentheses, so it would do the wrong
thing, and it used / rather than % to find a remainder. The effect of
these oversights is that the stop point chosen by the logic introduced in
commit b69bf30b9bfacafc733a9ba77c9587cf54d06c0c might be rather
meaningless.
Thomas Munro, reviewed by Kevin Grittner, with a whitespace tweak by me.
| -rw-r--r-- | src/backend/access/transam/multixact.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/src/backend/access/transam/multixact.c b/src/backend/access/transam/multixact.c index 928f9fe5d6c..cbb69f5e10c 100644 --- a/src/backend/access/transam/multixact.c +++ b/src/backend/access/transam/multixact.c @@ -2495,7 +2495,8 @@ DetermineSafeOldestOffset(MultiXactId oldestMXact) */ oldestOffset = find_multixact_start(oldestMXact); /* move back to start of the corresponding segment */ - oldestOffset -= oldestOffset / MULTIXACT_MEMBERS_PER_PAGE * SLRU_PAGES_PER_SEGMENT; + oldestOffset -= oldestOffset % + (MULTIXACT_MEMBERS_PER_PAGE * SLRU_PAGES_PER_SEGMENT); LWLockAcquire(MultiXactGenLock, LW_EXCLUSIVE); /* always leave one segment before the wraparound point */ |