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Re: Browsing the tables / why pgsql does not perform well (with temp fix)

From: The Hermit Hacker <scrappy(at)hub(dot)org>
To: Jan Vicherek <honza(at)ied(dot)com>
Cc: Hannu Krosing <hannu(at)trust(dot)ee>, pgsql-hackers(at)postgreSQL(dot)org, vadim(at)sable(dot)krasnoyarsk(dot)su
Subject: Re: Browsing the tables / why pgsql does not perform well (with temp fix)
Date: 1998-01-25 03:55:38
Message-ID: Pine.BSF.3.96.980124235139.28536A-100000@thelab.hub.org (view raw or flat)
Thread:
Lists: pgsql-hackers
On Sat, 24 Jan 1998, Jan Vicherek wrote:

> On Sat, 24 Jan 1998, Hannu Krosing wrote:
> 
> > > if aggregates were able to use indexes you could do:
> > >
> > > select min(n) from table where rowid >n;
> > >
> > > and then
> > >
> > > select * from table where n = n_found by_last_previous_select;
> > >
> > > but as they don't you would get very poor performance from the first
> > > select;
> 
>   This looks good. No transactions necessary, no locking, no mutliple rows
> copying.

	The SELECT above will create a READ lock on the table, preventing
UPDATES from happening for the duration of the SELECT.  There is *no* way
of getting around or away from this lock...

> > > So the real solution would be to use indexes for sorting, maybe at first
> > > for single field sorts.
> 
>     How many hours would that take to write ?

	As Bruce said in another posting, he isn't even sure *where* to
start on this, so I'd say over a month, if not longer...over a month in
the sense that as of the end of this week, there will be no new
developments on the source tree, only stabilization and bug fixes...


 

Marc G. Fournier                                
Systems Administrator @ hub.org 
primary: scrappy(at)hub(dot)org           secondary: scrappy(at){freebsd|postgresql}.org 


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Subject: Re: Browsing the tables / why pgsql does not perform well (with temp fix)
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