Re: Extremely Low performance with ODBC

Richard Broersma wrote:
> On Fri, May 23, 2008 at 9:47 AM, Sebastian Rychter
> <srychter@anvet.com.ar> wrote:
>> Thanks.. All logs are already off and I'm just sending one query directly
>> from the application (from Visual Foxpro using SQL Pass through and in
>> VB.net using ado.net). I've found that the "problem" is that I'm using
>> implicit joins, and when I change it to explicit Inner Joins the query only
>> takes 3 seconds (as with PgAdmin). I still can't understand if the problem
>> resides on the ODBC driver, the Query Planner or it's just a mix of both.
> 
> The next step would be to turn on PostgreSQL's statement logging and
> statement duration.  Issue the queries from VFP and then check what
> statement that PG is actually getting.  If the statement that PG is
> getting looks good, try executing that statement prefixed with explain
> analyze from the psql command line to help identify where the
> performance problem is.

You know what'd be incredibly handy for this sort of issue?

The ability to set an `always explain analyze' flag on a connection, 
preferably as a driver parameter (for ODBC/JDBC) or failing that as a 
per-connection variable like the ones to enable/disable seqscan, nested 
loop, etc.

That might really help with tracking down issues that appear to only 
happen with queries run by an app, or though a particular interface.

Can it be done? Or is the DB server not capable of generating explain 
output (say to a log) and also returning a resultset?

--
Craig Ringer