[Dbix-class] Weird RelationShip => SQL behavior and Performance Issue

[Matt S Trout]

On Thu, May 31, 2007 at 03:37:47PM +0200, Benoit Plessis wrote:
> 
> In fact i think it's the generation of the SQL query that take all the
> time or it could be the prefetching.

It's unlikely to be on the DBIC side.

Try setting DBIC_TRACE=1 and running the query against your DB yourself.

MySQL is notoriously crap at handling prefetches across many rels.

> Is it a way to prepare the resultset with all arguments except the
> search condition value, and just run the query in each loop ?
> Like the famous prepare / execute combo in DBI ?

DBIC effectively does that - for a given query it'll re-use the same
already-prepared $sth.

Don't try and micro-optimise your usage - somebody once built almost
exactly what you describe shortly before we implemented the current approach
and found it provided about a 2% speed improvement.

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