maria-developers team mailing list archive

[Zardosht Kasheff <zardosht@xxxxxxxxx>]

Is there something similar in MariaDB?


---------- Forwarded message ----------
From: Øystein Grøvlen <oystein.grovlen@xxxxxxxxxx>
Date: Tue, Feb 12, 2013 at 9:11 AM
Subject: Re: debugging how query plans are made
To: Zardosht Kasheff <zardosht@xxxxxxxxx>
Cc: "internals@xxxxxxxxxxxxxxx" <internals@xxxxxxxxxxxxxxx>


On 02/12/13 02:54 PM, Zardosht Kasheff wrote:
>
> Hello all,
>
> In MySQL and/or MariaDB, are there any hooks or methods one can use to
> learn why a query plan is chosen over alternatives? We sometimes
> notice that a different query plan is chosen for us than InnoDB (which
> may be fine, given we are a different storage engine), and we would
> like to better understand why. Is there any debug parameter that gets
> MySQL to output decisions made in the optimizer?


MySQL 5.6 has optimizer tracing which outputs the decisions made by
the optimizer.  See
http://dev.mysql.com/doc/internals/en/optimizer-tracing.html

Hope this helps,

--
Øystein