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| author | Robert Haas <rhaas@postgresql.org> | 2015-05-07 11:00:47 -0400 |
|---|---|---|
| committer | Robert Haas <rhaas@postgresql.org> | 2015-05-07 11:16:41 -0400 |
| commit | 83fbd9b59906c8543c165c738fc449af24491e63 (patch) | |
| tree | d7c7a79e432bbb82f27055c1feffe3f82d4cb79f | |
| parent | ba3caee8438e631eec2ddcbe7f4b87f70fbfc027 (diff) | |
| download | postgresql-83fbd9b59906c8543c165c738fc449af24491e63.tar.gz postgresql-83fbd9b59906c8543c165c738fc449af24491e63.zip | |
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 5532dc6fc82..424cceb1cf0 100644 --- a/src/backend/access/transam/multixact.c +++ b/src/backend/access/transam/multixact.c @@ -2514,7 +2514,8 @@ 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 */ |