Hi Monty, On Tue, Jun 21, 2016 at 9:30 AM, Michael Widenius <monty@mariadb.org> wrote:

Hi!

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"Nirbhay" == Nirbhay Choubey <nirbhay@mariadb.com> writes:

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Nirbhay> ALTER TABLE implementation takes a shortcut for operations not affecting Nirbhay> .frm files, Nirbhay> which includes simple RENAMEs. But this is skipped for temp tables and thus Nirbhay> copying Nirbhay> always takes place for temp tables.

Nirbhay> The following commit (from 2002) added this exception for temp tables: Nirbhay> https://github.com/MariaDB/server/commit/a7798dfd0a6472bf65fffc2ade543605e17...

The above old patch is not really working for the current code.

Nirbhay> I have created a patch to also include temp tables to this shortcut : Nirbhay> https://gist.github.com/nirbhayc/442a0c269ce48b283543cac434aaf44e

This solves the problem of doing a simple rename, but not for things like:

alter table t1 add column c int, rename to t2;

Which will still produce crashes.

When it comes to last_version, is still vote for that we should be using THD::rename_temporary_table when renaming temporary tables instead of doing any handler calls.

Right.

Maybe we could move THD::rename_temporary_tables to ha_rename_table to get all temporary tables handled in one place ?

handler::ha_rename_table() is currently being used only for non-temporary tables at places which do not support temporary tables like partitions, DDL logs, RENAME TABLE, etc. So, moving rename_temporary_table to ha_rename_table seem overkill and possibly inappropriate. Here's the latest version of patch : http://lists.askmonty.org/pipermail/commits/2016-June/009477.html Best, Nirbhay

Regards, Monty