From: | secret <secret(at)kearneydev(dot)com> |
---|---|
To: | Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us> |
Cc: | pgsql-sql(at)postgreSQL(dot)org |
Subject: | Re: [SQL] Very disappointing performance -- All Indexes Ignored. |
Date: | 1999-03-11 19:30:54 |
Message-ID: | 36E819EE.ED2911E6@kearneydev.com |
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Thread: | |
Lists: | pgsql-sql |
Bruce Momjian wrote:
> OK, some questions. First, how long does EXPLAIN take to run. It is a
> significant percentage of the query time? If so, please download the
> current snapshot, and try that. Should be much faster.
>
Not very long, maybe 10 seconds at maximum... I checked this because I
was
paranoid it might be that... No problem there.
>
> Second, indexes are not of a huge value in this query, because there are
> no restrictions, i.e. x=3. In most cases, walking the index and then
> going to the heap table takes longer than just reading the entire table
> into a hash and doing the join there.
I see, and after doing a more specific query(from_job_id=xxx) the speed
is much increased... The main thing that disturbed me is the rather large
time between the query with joins(300 seconds) and with the functions(30s)...
Shouldn't the functions be far slower?(Seems like they would be less
efficient)
PostgreSQL is also crashing 1-2 times a day on me, although I have a
handy perl script to keep it alive now <grin>... If PostgreSQL does work for
my project I'll of course buy CDs/books/whatever to support the project.
Despite the 2 problems I'm having I am very impressed with the project.
--David
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