> ------------------------------------------------------------
> 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.