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List:       postgresql-general
Subject:    Re: [HACKERS] Collect frequency statistics for arrays
From:       Tom Lane <tgl () sss ! pgh ! pa ! us>
Date:       2012-02-29 23:10:44
Message-ID: 26664.1330557044 () sss ! pgh ! pa ! us
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Nathan Boley <npboley@gmail.com> writes:
> On Wed, Feb 29, 2012 at 2:43 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Nathan Boley <npboley@gmail.com> writes:
>>> If I understand you're suggestion, queries of the form
>>> SELECT * FROM rel
>>> WHERE ARRAY[ 1,2,3,4 ] <= x
>>>      AND x <=ARRAY[ 1, 2, 3, 1000];
>>> would no longer use an index. Is that correct?

>> No, just that we'd no longer have statistics relevant to that, and would
>> have to fall back on default selectivity assumptions.

> Which, currently, would mean queries of that form would typically use
> a table scan, right?

No, it doesn't.

> What about MCV's? Will those be removed as well?

Sure.  Those seem even less useful.

			regards, tom lane

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