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Re: MDEV-6714: A couple of questions


Hi, Vicențiu!

On Mar 16, Vicențiu Ciorbaru wrote:
> I've achieved the desired performance speedup related to MDEV-6714.
> You can check the preliminary patch on the commits mailing-list. I'll
> clean up the code and then submit a final version for review. I do
> however have two concerns:
> * By using SHOW TABLES LIKE %s, we performed a case insensitive search to
> find the table's correct name case. This command takes a long time with a
> lot of tables. Using an equality operator in I_D speeds it up, but it no
> longer matches if we have a different case.
> Possible solution: Try to search for the table with the provided string via
> INFORMATION_SCHEMA using the equals operator. If we can not find the table,
> fall back to a case insensitive search that takes longer.

Okay, good idea.
A drawback is that if the table doesn't exist, you'll need a slow search
to find it out. But I don't see a solution for this.

At least, you could check lower_case_table_names. And if it's not 0, you
don't need to do a case insensitive search.

> * The I_S.triggers and I_S.tables are available since 5.5 and 5.1
> respectively. I suppose it is safe to assume we will have these tables
> available when running mysqldump. I can code all the changes to fall back
> to the previous query if the one that uses I_S tables fails.

Right, fallback is fine.