***BOGO*** Re: MyIsam Locking Questions

["Perrin Harkins" <perrin@xxxxxxxx>]

On Thu, Aug 28, 2008 at 10:59 AM, Jose Estuardo Avila
<tachu@xxxxxxxxxxxxxxx> wrote:
> I understand that reads are locked by writes but nowhere does of mention
> that reads also block reads.

How could they not?  You can't simultaneously read and write the same
data -- the read would get half-written garbage.  Read locks are
shared, but write locks are exclusive, so they have to wait for reads
to finish.

You may find this section on locking helpful:
http://dev.mysql.com/doc/refman/5.0/en/internal-locking.html

It also links to an explanation of concurrent inserts, which is a
specific situation where MyISAM can handle reads and writes
concurrently.

For any application that has a significant percentage of writes or
long-running SELECTs, you will get better concurrency from InnoDB with
its MVCC approach.

- Perrin

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