pgsql: Fix query-duration memory leak with GIN rescans.

From: Heikki Linnakangas <heikki(dot)linnakangas(at)iki(dot)fi>
To: pgsql-committers(at)postgresql(dot)org
Subject: pgsql: Fix query-duration memory leak with GIN rescans.
Date: 2015-01-30 17:18:21
Message-ID: E1YHFD3-0000gX-Ff@gemulon.postgresql.org
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-committers

Fix query-duration memory leak with GIN rescans.

The requiredEntries / additionalEntries arrays were not freed in
freeScanKeys() like other per-key stuff.

It's not obvious, but startScanKey() was only ever called after the keys
have been initialized with ginNewScanKey(). That's why it doesn't need to
worry about freeing existing arrays. The ginIsNewKey() test in gingetbitmap
was never true, because ginrescan free's the existing keys, and it's not OK
to call gingetbitmap twice in a row without calling ginrescan in between.
To make that clear, remove the unnecessary ginIsNewKey(). And just to be
extra sure that nothing funny happens if there is an existing key after all,
call freeScanKeys() to free it if it exists. This makes the code more
straightforward.

(I'm seeing other similar leaks in testing a query that rescans an GIN index
scan, but that's a different issue. This just fixes the obvious leak with
those two arrays.)

Backpatch to 9.4, where GIN fast scan was added.

Branch
------
REL9_4_STABLE

Details
-------
http://git.postgresql.org/pg/commitdiff/dc40ca696313ee8f7e75bb7628990e6e138b0e01

Modified Files
--------------
src/backend/access/gin/ginget.c | 10 +++++++---
src/backend/access/gin/ginscan.c | 16 ++++++++++++----
src/include/access/gin_private.h | 1 +
3 files changed, 20 insertions(+), 7 deletions(-)

Browse pgsql-committers by date

  From Date Subject
Next Message Tom Lane 2015-01-30 17:31:17 pgsql: Fix assorted oversights in range selectivity estimation.
Previous Message Kevin Grittner 2015-01-30 15:11:08 pgsql: Allow pg_dump to use jobs and serializable transactions together