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Re: same question little different test MSSQL vrs Postgres

From: "Joel Fradkin" <jfradkin(at)wazagua(dot)com>
To: "'Richard Huxton'" <dev(at)archonet(dot)com>
Cc: <gsstark(at)mit(dot)edu>, <pgsql-sql(at)postgresql(dot)org>
Subject: Re: same question little different test MSSQL vrs Postgres
Date: 2005-01-26 14:58:00
Message-ID: 000001c503b7$6ea08800$797ba8c0@jfradkin (view raw or flat)
Thread:
Lists: pgsql-sql
Well last evening (did not try it this morning) it was taking the extra
time.

I have made some adjustments to the config file per a few web sites that you
all recommended my looking at.

It is now using 137 of 756 meg avail.
it is now taking 8 secs to return 22,000 rows (using pgadminIII in a sql
edit window).

The EXPLAIN ANALYSE still shows the same as below, but the table has 344,000
recs of which only 22636 are clientnum = 'SAKS'

I am still doing a seq search (this applies to the view question where if it
is a small result set it used a index search but on a larger return set it
did a seq search) in my view, but with the adjustments to the kernel I get a
result in 140 secs (MSSQL was 135 secs).

This is not production, I am still very worried that I have to do all this
tweeking to use this, MSSQL worked out of the box as it does (not saying its
great, but I never had to adjust a kernel setting etc). Since we cannot
afford the 70,000 dollars they want to license it I am not implying I can
use MSSQL, but I could look at other DB's like MYSQL, or Firebird, etc.

I have a lot of time now (two weeks) in this conversion and do not wish to
give up, I will see if I can learn what is needed to get the maximum
performance. I have seen much information available and this list has been a
huge resource. I really appreciate all the help.


Joel Fradkin
 
Wazagua, Inc.
2520 Trailmate Dr
Sarasota, Florida 34243
Tel.  941-753-7111 ext 305
 
> QUERY PLAN
> "Seq Scan on tblcase  (cost=0.00..30066.21 rows=37401 width=996) (actual
> time=0.344..962.260 rows=22636 loops=1)"
> "  Filter: ((clientnum)::text = 'SAKS'::text)"
> "Total runtime: 1034.434 ms"

That's only 1 second - to return 22,636 rows. Not 27 seconds, as in the 
original post. You'll never persuade PG to use the index when some 75% 
of your rows match the filter - it just doesn't make sense.

--
   Richard Huxton
   Archonet Ltd


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