Re: Why is indexonlyscan so darned slow?

On 21 May 2012 16:02, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Simon Riggs <simon@2ndQuadrant.com> writes:
>> Surely the way to solve this is by having a new plan node that does a
>> physical SeqScan of the index relation. It means we wouldn't preserve
>> the sort order of the rows from the index, but that is just a plan
>> cost issue.
>
>> This is exactly what we do for VACUUM and it works faster there.
>
> The reason that's okay for vacuum is that vacuum doesn't care if it
> visits the same index tuple multiple times.  It will not work for real
> queries, unless you would like to lock out all concurrent inserts.

I checked a little more and Oracle supports something called a Fast
Index Scan. Maybe there is a way.

--
 Simon Riggs                   http://www.2ndQuadrant.com/
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