Re: Django SQL Query does not stop

Hi Chris,

thanks for the info. My tables won't have many rows and I don't have the time for optimazation, especially if it is not necessary, but I will keep your words in mind!

Cheers
Ivo

On 02.02.2011, at 06:10, Chris Matthews wrote:

> Hi Ivo,
>
> SQL is like regular expressions. You can go complex (with one mega query/expression) but it could create a maintenance nightmare. See if you cannot simplify the query into multiple queries and a bit of code (for loops and using the joining columns) to lash them together. The code sequence should be such that you limit access to a huge amount of rows; so you filter the data accessed. It is usually easier to debug as well. And using Tom's advice (EXPLAIN SELECT ...) on smaller join queries is often more useful (than the explain on a mega join query).
>
> In my experience it often runs way faster if the query is simplified.
>
> Regards
> Chris
> -----Original Message-----
> From: django-users@googlegroups.com [mailto:django-users@googlegroups.com] On Behalf Of Ivo Brodien
> Sent: 01 February 2011 23:49
> To: django-users@googlegroups.com
> Subject: Re: Django SQL Query does not stop
>
> I found a solution be changing the MySQL server setting optimizer_search_depth to 3 (default 62)
>
> http://dev.mysql.com/doc/refman/5.0/en/controlling-optimizer.html
> http://dev.mysql.com/doc/refman/5.0/en/server-system-variables.html#sysvar_optimizer_search_depth
>
> My query had over 20 INNER JOINTS and it made the optimizer search a long process.
>
> So at the moment a value of 3 is fine.
>
> On 01.02.2011, at 21:20, Ivo Brodien wrote:
>
>> The Change List that I am calling is a Intermediate Table if that is of any interest.
>>
>> Is it possible that there is some sort of circular inner joints or something?
>>
>>
>
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