Hi Sergei
On 25/05/2009, at 7:39 PM, Sergei Golubchik wrote:
>> 3. Are all I_S tables created when user performs select statment
>> about
>> just one of tables of I_S?
>
> No, of course not. Only those tables that are mentioned in the query
> are created.
Given the level of sanity in sql_show.cc, that's not really an "of
course" case, is it?
I mean, if I do a query about 1 table on an information schema table,
then mysqld will first run through all tables in all databases,
prouduce the temporary table of everything (most likely on disk), and
then run my query on it.
Try this on a busy production server, and you may be charged for
server murder. That's the real world.
Please see this as a vote of encouragement for the project.
I sincerely hope that an I_S engine will deal (more) sensibly with
these issues.
Cheers,
Arjen.
--
Arjen Lentz, Director @ Open Query (http://openquery.com)
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