From: | Seth Ladd <seth(at)picklematrix(dot)net> |
---|---|
To: | pgsql-performance(at)postgresql(dot)org |
Subject: | ways to force index use? |
Date: | 2003-10-13 23:48:15 |
Message-ID: | B6A1D046-FDD7-11D7-A960-000A9576D038@picklematrix.net |
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Lists: | pgsql-hackers pgsql-performance |
Hello,
Thanks to all the previous suggestions for my previous question. I've
done a lot more research and playing around since then, and luckily I
think I have a better understanding of postgresql.
I still have some queries that don't use an index, and I was wondering
if there were some other tricks to try out?
My system: RH9, PG 7.3.4, IDE, 1 gig RAM, celeron 1.7
My Table Columns (all bigints): start, stop, step1, step2, step3
My Indexes: btree(start), btree(stop), btree(start, stop)
Size of table: 16212 rows
Params: shared_buffers = 128, effective_cache_size = 8192
The Query: explain analyze select * from path where start = 653873 or
start = 649967 or stop = 653873 or stop = 649967
The Result:
Seq Scan on "path" (cost=0.00..450.22 rows=878 width=48) (actual time=0
.08..40.50 rows=1562 loops=1)
Filter: (("start" = 653873) OR ("start" = 649967) OR (stop = 653873) OR
(stop = 649967))
Total runtime: 42.41 msec
Does anyone have a suggestion on how to get that query to use an index?
Is it even possible? I did run vacuum analyze right before this test.
I'm only beginning to customize the parameters in postgresql.conf
(mainly from tips from this list).
Thanks very much!
Seth
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