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| Robert Allely... |
 Posted: Fri Nov 06, 2009 6:15 am |
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Ingres 9.2 with a new install sets opf_hash_join ON but if you upgrade the installation from Ingres 2.6 this setting is left off.
Presumable to avoid problems with some existing queries.
I assume that set on is going to help efficiency sometimes - does anyone know about this?
Interesting that if I hadn't
used a fresh install on one of the installations I would not have known to change it to on.
Robert Allely
Ports of Auckland NZ
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| Roy Hann... |
| Posted: Fri Nov 06, 2009 1:16 pm |
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Robert Allely wrote:
Quote: Ingres 9.2 with a new install sets opf_hash_join ON but if you upgrade the installation from Ingres 2.6 this setting is left off.
Presumable to avoid problems with some existing queries.
I assume that set on is going to help efficiency sometimes - does anyone know about this?
Interesting that if I hadn't
used a fresh install on one of the installations I would not have known to change it to on.
Unless you have a good reason to turn it off in 9.2 you should turn it
on. Hash joins have been working reliably for quite a while.
Another similar gotcha to look out for is the introduction of new
parameters that don't get added during the upgrade, so you get whatever
the default behaviour is but you don't know you have an option.
--
Roy
UK Ingres User Association Conference 2010 will be on Tuesday June 8 2010
Go to http://www.iua.org.uk/join to get on the mailing list. |
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