maria-discuss team mailing list archive

[Sergei Golubchik <serg@xxxxxxxxxxx>]

Hi, Rhys.Campbell!

On May 04, Rhys.Campbell@xxxxxxxxxxxx wrote:
> Hi All,
> 
> For the following statement...
> 
> ALTER ONLINE TABLE dom_audit_event ENGINE=INNODB, ALGORITHM=INPLACE;
> 
> I can still see that MariaDB is still using the value of tmpdir. We
> have this set to tmpfs on some of our servers and this causes some
> ALTER statements on big tables to fail. It was my understanding that
> if you specified INPLACE then the statement would fail if this was not
> possible.

Yes, your understanding is correct.

Furthermore, copy (not inplace) ALTER does not use tmpdir, it creates a
temporary table in the datadir, and later renames it to the actual table
name. If the temporary table were created in tmpdir, it could not be
renamed to a different filesystem.

So, that tmpdir usage you're seeing is not due to not-inplace alter.
The alter isstill done inplace, and tmpdir is used for something else.
Probaby for merge sort.

Regards,
Sergei
Chief Architect MariaDB
and security@xxxxxxxxxxx