> > I don't know how big of a performance boost it provides in the cache, but
> > removing the functions associated with the char types shrank the pg_proc
> > table from 906 to 842 entries or a bit over 7%.
> > 
> > Want to shrink it further?  Of those remaining 842, _230_ are for the geometric
> > types!  Throw in 25 more for the cash/money functions.  Bloat city if you
> > never use these things.  Thirty percent could be moved out to contrib and
> > not missed by most postgres users.
> > 
> 
> Yes, but if they are never referenced, the cache is empty for those
> types.  Unless there is some performance change with their removal, why
> remove them?  Disk space of binary?

How does the cache really work then?  Does one pg disk block map to one buffer?

When you say "the cache is empty for those types.", what do you mean?

darrenk

Tue, 24 Mar 1998 10:10:05 -0500
darrenk@insightdist.com (Darren King)
Re: [HACKERS] char types gone.
On Tue, 24 Mar 1998, Darren King wrote:

> > > I don't know how big of a performance boost it provides in the cache, but
> > > removing the functions associated with the char types shrank the pg_proc
> > > table from 906 to 842 entries or a bit over 7%.
> > > 
> > > Want to shrink it further?  Of those remaining 842, _230_ are for the geometric
> > > types!  Throw in 25 more for the cash/money functions.  Bloat city if you
> > > never use these things.  Thirty percent could be moved out to contrib and
> > > not missed by most postgres users.
> > > 
> > 
> > Yes, but if they are never referenced, the cache is empty for those
> > types.  Unless there is some performance change with their removal, why
> > remove them?  Disk space of binary?
> 
> How does the cache really work then?  Does one pg disk block map to one buffer?
> 
> When you say "the cache is empty for those types.", what do you mean?

I think there's some confusion about which cache is meant. I think the 
previous poster (ie. the one before darren) is thinking of processor 
cache, be it first level or second level. Darren is probably meaning a 
postgresql internal cache....

Maarten

_____________________________________________________________________________
| TU Delft, The Netherlands, Faculty of Information Technology and Systems  |
|                   Department of Electrical Engineering                    |
|           Computer Architecture and Digital Technique section             |
|                          M.Boekhold@et.tudelft.nl                         |
-----------------------------------------------------------------------------


Tue, 24 Mar 1998 18:02:46 +0100 (MET)
Maarten Boekhold <maartenb@dutepp2.et.tudelft.nl>
Re: [HACKERS] char types gone.
> > > I don't know how big of a performance boost it provides in the cache, but
> > > removing the functions associated with the char types shrank the pg_proc
> > > table from 906 to 842 entries or a bit over 7%.

No performance impact.

> > > Want to shrink it further?  Of those remaining 842, _230_ are for the geometric
> > > types!  Throw in 25 more for the cash/money functions.  Bloat city if you
> > > never use these things.  Thirty percent could be moved out to contrib and
> > > not missed by most postgres users.
> > 
> > Yes, but if they are never referenced, the cache is empty for those
> > types.  Unless there is some performance change with their removal, why
> > remove them?  Disk space of binary?
> 
> How does the cache really work then? Does one pg disk block map to one buffer?
> 
> When you say "the cache is empty for those types.", what do you mean?

The function cache has one entry for each function in use. If a function has
never been called, then no cache entry is ever created for it. The cache
is organized per function, it is not part of the buffer / page cache so
each entry only takes a few bytes.

-dg

David Gould            dg@illustra.com           510.628.3783 or 510.305.9468 
Informix Software  (No, really)         300 Lakeside Drive  Oakland, CA 94612
 - Linux. Not because it is free. Because it is better.


Tue, 24 Mar 1998 11:17:40 -0800 (PST)
dg@illustra.com (David Gould)
Re: [HACKERS] char types gone.
> > Yes, but if they are never referenced, the cache is empty for those
> > types.  Unless there is some performance change with their removal, why
> > remove them?  Disk space of binary?
> 
> How does the cache really work then?  Does one pg disk block map to one buffer?
> 
> When you say "the cache is empty for those types.", what do you mean?

I believe the buffer page cache does load in those types if they are in
the same page as a requsted type, but the relation/function caches only
store in requested relations/functions, as far as I know.

-- 
Bruce Momjian                          |  830 Blythe Avenue
maillist@candle.pha.pa.us              |  Drexel Hill, Pennsylvania 19026
  +  If your life is a hard drive,     |  (610) 353-9879(w)
  +  Christ can be your backup.        |  (610) 853-3000(h)

Tue, 24 Mar 1998 21:38:35 -0500 (EST)
Bruce Momjian <maillist@candle.pha.pa.us>
Re: [HACKERS] char types gone.