Backport into build-200911241145-5.1.40sp1
> ------------------------------------------------------------ > revno: 3190 [merge] > revision-id: kostja@sun.com-20091103174552-bfpak6r7ngf5cbjb > parent: magnus.blaudd@sun.com-20091103170719-6b64sjnivsiyz6xy > parent: kostja@sun.com-20091103165854-7di545xruez8w207 > committer: Konstantin Osipov <kostja@sun.com> > branch nick: 5.1-41756 > timestamp: Tue 2009-11-03 20:45:52 +0300 > message: > A fix and a test case for > Bug#41756 "Strange error messages about locks from InnoDB". > > In JT_EQ_REF (join_read_key()) access method, > don't try to unlock rows in the handler, unless certain that > a) they were locked > b) they are not used. > > Unlocking of rows is done by the logic of the nested join loop, > and is unaware of the possible caching that the access method may > have. This could lead to double unlocking, when a row > was unlocked first after reading into the cache, and then > when taken from cache, as well as to unlocking of rows which > were actually used (but taken from cache). > > Delegate part of the unlocking logic to the access method, > and in JT_EQ_REF count how many times a record was actually > used in the join. Unlock it only if it's usage count is 0. > > Implemented review comments. > ------------------------------------------------------------ > Use --include-merges or -n0 to see merged revisions.
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