Re: Dramatic slowdown of sql when placed in a function

Jeff Boes <jboes(at)nexcerpt(dot)com> wrote in message news:<971d398a3317a5af5086277b2a1487f4(at)news(dot)teranews(dot)com>...
> At some point in time, mike_moran(at)mac(dot)com (Mike Moran) wrote:
>
> >Hi. I currently have a fairly large query which I have been optimizing
> >for later use in a function. There are things in the query which I
> >have been keeping constant whilst optimizing, but which are variables
> >in the function. When I run this query as sql, with the `variables'
> >constant, I get a runtime of about 3 or 4 seconds. However, when I
> >place this same sql in an sql function, and then pass my constants
> >from before in as arguments, I get a runtime of about 215 seconds.
> >
[ ... ]
>
> My first guess would be that the indexes being used in the query are
> mis-matching on data type compared to your function arguments. For instance,
[ ... ]

Hi. I think it is something like this that is going on. A couple of
the variables are dates which are
specified in the table as 'timestamp without time zone', whilst the
function was using 'timestamp with time zone'. I confirmed the
slowdown by casting the types to the 'slow' type in the original
query.

However, when I change the signature of the function and do a cast of
the variable within the function body I still get the same speed. I
even cast the arguments to the function given at the psql prompt and
still I get the same speed.

I will have to sanity-check this again tomorrow (posting from home)
but I couldn't see anywhere else that I could force the type to be the
same as that specified on the table.

Many thanks,

--
Mike