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Received: by postgres.Berkeley.EDU (5.61/1.29)
	id AA09995; Tue, 21 Jul 92 10:06:42 -0700
Message-Id: <9207211706.AA09995@postgres.Berkeley.EDU>
From: postarch (Postgres Mailing Archive)
Subject: Re: Hashjoin
To: postgres@postgres.berkeley.edu
Sender: pg_adm@postgres.berkeley.edu
Reply-To: mer@postgres.berkeley.edu
In-Reply-To: Your message of "Fri, 17 Jul 92 19:56:20 PDT."
             <9207180256.AA03266@postgres.Berkeley.EDU> 
Date: Tue, 21 Jul 92 10:06:32 PDT

you write:

> When I do join by using hashjoin in postgres, I got the following message
> 
> NOTICE:Jul 17 19:52:32:hash table out of memory. expanding.
> NOTICE:Jul 17 19:52:33:PortalHeapMemoryFree: 0x29b840 not in alloc set!
> 
> What's the exact reason? How to avoid it? Thanks!!

I assume you are using postgres version 4 and not 3.1?

I'm not sure on either count offhand.  This is a bug, and I would like to
see your schema, the retrieve query that generated the above NOTICEs, and
some sampling of your data.

One way you can try to avoid the problem is by defining indices on the join
attributes.  This should cause the planner to plan nestloop or mergejoins
over index scans, thereby avoiding hashjoins altogether.


Jeff Meredith
mer@postgres.berkeley.edu