LOCK TABLES on compressed tables...

[Michael Widenius]

Hi!

>>>>> "Paul" == Paul Cadach <paul@stripped> writes:

Paul> Hi,
Paul> I'm uses write locks to prevent other people to write to table when I'm
Paul> updates it. When updating I need to select some additional values from other
Paul> table, so I must lock it too. But because table is compressed (aka
Paul> read-only), I can't lock it with write lock. Why?

Because you don't have the permission to use a write lock on the
table.

Why can't you use a READ lock on the compressed tables.

You will get more concurrency if you use READ locks on tables you just
read from...

Paul> As I understand, write lock delays any writes to locked table performed by
Paul> other connections until a table is unlocked. In case with compressed
Paul> (read-only) table, it can be treaded as 'locked for write' all times when
Paul> LOCK TABLE ... WRITE issued.

I still don't see a reason for using a WRITE lock here.

I think it's actually right that you get an error on this, as you will
not be able to update the table anyway.

Regards,
Monty