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Re: Planner question - "bit" data types

From: Karl Denninger <karl(at)denninger(dot)net>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Merlin Moncure <mmoncure(at)gmail(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Planner question - "bit" data types
Date: 2009-09-05 21:39:45
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
Tom Lane wrote:
> Karl Denninger <karl(at)denninger(dot)net> writes:
>> That doesn't help in this case as the returned set will typically be
>> quite large, with the condition typically being valid on anywhere from
>> 10-80% of the returned tuples.
> In that case you'd be wasting your time to get it to use an index
> for the condition anyway.  Maybe you need to take a step back and
> look at the query as a whole rather than focus on this particular
> condition.
> 			regards, tom lane
The query, sans this condition, is extremely fast and contains a LOT of
other conditions (none of which cause trouble.)

It is only attempting to filter the returned tuples on the permission
bit(s) involved that cause trouble.

-- Karl

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