Date: Tue, 29 Jul 2003 22:57:27 -0400
From: Mark Bronnimann <meb@speakeasy.net>
To: Rod Taylor <rbt@rbt.ca>
Cc: pgsql-sql@postgresql.org
Subject: Re: function returning setof performance question
Message-ID: <20030730025727.GA2094@spiff.astoria.bogus>
References: <20030730020859.GA1795@spiff.astoria.bogus>
	<1059532098.54325.23.camel@jester>
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  Thanks for the reply. 

  I was hoping to eliminate the parse call on the view because I was doing 
the where clause on the view instead of putting the where in the view. 
In all, I was hoping to keep a single view called from multiple functions 
with different where clauses. Yep... I shoulda known better...

  Thanks again!


And Rod Taylor (rbt@rbt.ca) said...:

> > The performance hit is tiny, we're talking less than 1/2 a second, 
> > but when I've done this sort of thing in Oracle I've seen a performance 
> > increase, not a decrease. 
> 
> Thats just plain strange (never tried on Oracle).  Why in the world
> would adding the overhead of a function call (with no other changes)
> increase performance?
> 
> The function has additional overhead in the form of the plpgsql
> interpreter.  You may find a c function will give close to identical
> performance as with the standard view so long as the query is the same.
> 
> 
> One thing to keep in mind is that the view can be rearranged to give a
> better query overall. The exact work completed for the view may be
> different when called from within a different SQL statement.  Most
> functions -- some SQL language based functions are strange this way --
> cannot do this
> 


-- 

Mark Bronnimann
meb@speakeasy.net
      
-- Let's organize this thing and take all the fun out of it. --