Re: More 8.2 client issues (Was: [Slow dump?)

[Erik Jones <erik(at)myemma(dot)com>]

Tom Lane wrote:
> Erik Jones <erik(at)myemma(dot)com> writes:
>   
> > Tom Lane wrote:
> >     
> > > I could see this taking an unreasonable amount of time if you had a huge
> > > number of pg_class rows or a very long search_path --- is your database
> > > at all out of the ordinary in those ways?
> > >
> > >       
> > Well, running "select count(*) from pg_class;" returns 524699 rows
> >     
>
> Ouch.
>
>   
> > our search path is the default.  I'd also like to reiterate that \d 
> > pg_class returns instantly when run from the 8.1.4 psql client connected 
> > to the 8.2 db.
> >     
>
> I think I know where the problem is: would you compare timing of
>
> 	select * from pg_class where c.relname ~ '^(pg_class)$';
>   
Approximately 4 seconds.
> 	select * from pg_class where c.relname ~ '^pg_class$';
>   
Instant.
> Recent versions of psql put parentheses into the regex pattern for
> safety in case it's got "|", but I just realized that that probably
> confuses the optimizer's check for an indexable regex :-(
>
> However, this only explains slowdown in psql's \d commands, which
> wasn't your original complaint ...
>   
Well, it explains the slowdown wrt a query against the catalog tables by 
a postgres client application.  Were there any changes made like this to 
pg_dump and/or pg_restore?

--
erik jones <erik(at)myemma(dot)com>
software development
emma(r)