Subject: Hashjoin

From: [email-masked] (Postgres Account)
Date: Fri, 17 Jul 92 19:56:20 -0700

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!!

--Shengsong Ni

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From: postarch (Postgres Mailing Archive)
Date: Tue, 21 Jul 92 10:06:32 PDT

> 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
[email-masked]