* Jon Olav Hauglid <jon.hauglid@stripped> [10/07/23 13:14]:
> 3084 Jon Olav Hauglid 2010-07-23
> Bug #55498 SHOW CREATE TRIGGER takes wrong type of metadata lock
>
> The first problem was that SHOW CREATE TRIGGER took a stronger metadata
> lock than required. This caused the statement to be blocked when it was
> not needed. For example, LOCK TABLE WRITE in one connection would block
> SHOW CREATE TRIGGER in another connection.
>
> Another problem was that a SHOW CREATE TRIGGER statement issued inside
> a transaction did not release its metadata locks at the end of the
> statement execution. This happened even if SHOW CREATE TRIGGER is an
> information statement. The consequence was that SHOW CREATE TRIGGER
> was able to block other connections from accessing the table
> (e.g. using ALTER TABLE).
>
> This patch fixes the problem by changing SHOW CREATE TRIGGER to take
> a MDL_SHARED_HIGH_PRIO metadata lock similar to what is already done
> for SHOW CREATE TABLE. The patch also changes SHOW CREATE TRIGGER to
> explicitly release any metadata locks taken by the statement after
> it completes.
OK to push.
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