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mysqlmyisam

How long will a MyISAM table lock by default?

I'm seeing a pending insert lock up a MyISAM table. The query itself isn't a standout, but in the FULL PROCESSLIST it looks like there's an INSERT with a lock and a bunch of SELECTs waiting on it.

The query itself isn't a standout. Reading the MySQL docs, I see something that is a standout: "If there are holes, concurrent inserts are disabled."

I presume this means holes in the index, and in my index here there is definitely "holes" in the sense that there are not consecutive ID numbers in the primary key. So I'm wondering: if concurrency is disabled and some INSERT hangs, how long is it going to hold that lock and will it hold that lock on the entire table (and not just the row)?

Solution

  • MyISAM does not support row level locking, so the lock is on entire table. I didn't find any information about lock timeout, it seems that insert can theoretically hang forever.