db-derby-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Katherine Marsden <kmarsdende...@sbcglobal.net>
Subject Re: Peculiar sorting behaviour?
Date Tue, 02 Apr 2013 17:05:23 GMT
On 4/2/2013 9:53 AM, John English wrote:
> On 02/04/2013 18:34, Knut Anders Hatlen wrote:
>> My guess is that it's the sort avoidance code that somehow gets confused
>> into thinking the result is already in the correct order and that the
>> sorting could be skipped. Hope you manage to reproduce it so we can fix
>> it.
>
> OK, this sounds possible. However, I've just tried a stripped-down 
> example using a prepared statement (yes, the username is a PS 
> parameter) and it works correctly, so I'm still trying.
>
> Is there a way to get at the execution plan at the right level of 
> detail that I could use to see what's happening on a copy of the live 
> database?
In derby.properties set:

derby.language.logStatementText=true
derby.language.logQueryPlan=true

> (I am a bear of very little brain when it gets to understanding 
> execution plans!)
>
     If you can post  the two plans, someone might be able to give you 
the optimizer overrides to force the plan with incorrect sorting.

> Many thanks,


Mime
View raw message