On Mar 7, 2014, at 10:20 AM, Robin Smith <[email protected]> wrote:

> I'm not sure about fetch plans, all i know at the moment is if i remove the 
> LIMIT query i get millisecond performance on my query but if i include a 
> LIMIT clause i get a full table scan.

You can log the query WO generates and run that through EXPLAIN? Try it with 
and without the limit.

> 
> 
> On 7 March 2014 17:15, Jesse Tayler <[email protected]> wrote:
> did you check to make sure your database is using the index fetch plan you 
> expect?
> 
> I recall with MySQL sometimes indexes would fail but there would be no 
> indication until I actually reviewed the fetch internals…
> 
> something chuck would know off the top of his head I’m sure…
> 
> 
> 
> 
> On Mar 7, 2014, at 12:02 PM, Robin Smith <[email protected]> wrote:
> 
>> Hi All
>> 
>> We have been experiencing some performace issues with our DB queries that we 
>> have narrowed down to the "limitClause" applied to sql queries. It seems 
>> that out of the box MySQL uses no indexes when supplied with a LIMIT clause.
>> 
>> Taking this into consideration we were wondering if anything like batch 
>> fetch iterator rely on the limit clause being applied to queries or if we 
>> could safely remove (or add switch to) this part of _MySqlPlugin.
>> 
>> Thanks
>> 
>> Robin
>> 
>> -- 
>> Robin Smith
>> Engineering Team Leader  BEng (Hons) MBCS
>> 
>> http://www.clicktravel.com
>> 
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> 
> 
> 
> 
> -- 
> Robin Smith
> Engineering Team Leader  BEng (Hons) MBCS
> 
> http://www.clicktravel.com
> 
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