long runtimes cured by cutting hash_area_size by 90% - ???

From: Chris Barr <cbarr_at_hotpop.com>
Date: Mon, 07 Apr 2003 20:43:38 -0800
Message-ID: <F001.0057C81C.20030407204338@fatcity.com>

Hash_Area_Size       runtime
10,000,000            6:16  ( 6+ mins )
  1,000,000            0:15  ( 16 secs)

Why?
Isn't bigger always better for hash_area_size? Is another param affected?

That's the only param that changed, via alter session.

Oracle 8.1.7, Sun/Solaris, 8 cpus, lots & lots of memory, no other queries, or 3 concurrent: same runtime.

The query joins 9 tables, one has 1.8M rows, the others under 60k rows.

Explain Plan shows 5 nested loops, 3 hash joins, and no diff between plans with the 2 values.

Chris Barr

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Author: Chris Barr
  INET: cbarr_at_hotpop.com

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