From: | Howie <caffeine(at)toodarkpark(dot)org> |
---|---|
To: | "Gene Selkov Jr(dot)" <selkovjr(at)mcs(dot)anl(dot)gov> |
Cc: | pierre <pierre(at)desertmoon(dot)com>, pgsql-sql(at)postgreSQL(dot)org |
Subject: | Re: [SQL] Joining bug???? |
Date: | 1998-10-27 23:48:56 |
Message-ID: | Pine.LNX.3.96.981027184101.589F-100000@brap-eth0.toodarkpark.org |
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Thread: | |
Lists: | pgsql-sql |
On Mon, 26 Oct 1998, Gene Selkov Jr. wrote:
>
> > I've been attempting to get my DB tuned to handle joins as best as
> > possible. However, no matter which way I try to perform the joins, if I
> > attempt to join more than two or three tables the joins becomes
> > unbearably long not matter how many indexes I create in however many ways.
>
> Ditto. Never saw a quadruple join succeed, even with relatively small tables.
Ive been playing with the idea of moving a client from MySQL to Postgres (
views, triggers, and subselects would _really_ make my life easier ).
---[ CUT ]---
SELECT
account.accnum,
account.accname,
((customers.firstname || ' ') || customers.lastname) as Customer,
acctype.descr,
account.balance,
account.status,
billdate.next
FROM
account,customers,acctype,billdate
WHERE
account.custnum=customers.custnum AND
account.acctype=acctype.accid AND
account.accnum=billdate.accnum AND
account.accnum<20
ORDER BY
account.accnum
---[ CUT ]---
works perfectly, takes about 2 seconds to complete. granted i have
( sometimes unique ) indexes on all the join columns.
account has 7k rows, customers has 5k rows, acctype has 12 rows,
billdate has 7k rows.
a somewhat modified, real-world query ends up crashing postgres, though:
---[ CUT ]---
select
account.accnum,
account.accname,
account.totalfee,
billdate.next,
((customers.firstname || ' ') || customers.lastname) as Customer,
customers.company,
customers.street,
acctype.yearly
FROM
account,customers,acctype,billdate
where
account.totalfee>0.00 AND
billtype=1 OR (billcc1stmo=1 AND account.created=billdate.last)
AND
balance<>0.00 AND
billdate.next>='1998-01-01' AND
billdate.next<='1998-01-05' AND
account.status<>'C' AND
billdate.accnum=account.accnum AND
account.custnum=customers.custnum AND
account.acctype=acctype.accid
---[ CUT ]---
> > My only solution was to create a hybrid table that contains the join of
> > all of the tables I'm searching on with multi-keyed indexes. This is a
> > VERY kludgy solution that makes changing the keys to my DB hard to change.
>
> The solution I use may be the worst imaginable kludge, but it works
> great: I do the joins (as well as other set operations) on the client
> side. Perl hashes are very good for that.
try making a view. from what others have said, views save the query plan
and have usually, at least for me, been _alot_ faster than normal queries.
---
Howie <caffeine(at)toodarkpark(dot)org> URL: http://www.toodarkpark.org
"Oh my god, they killed init! YOU BASTARDS!"
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