Re: get_actual_variable_range vs idx_scan/idx_tup_fetch

From: Marko Tiikkaja <marko(at)joh(dot)to>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: get_actual_variable_range vs idx_scan/idx_tup_fetch
Date: 2014-10-17 22:49:54
Message-ID: 54419D12.6030501@joh.to
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On 10/18/14, 12:15 AM, Tom Lane wrote:
> Marko Tiikkaja <marko(at)joh(dot)to> writes:
>> I think there's a big difference between "this index was used to look up
>> stuff for planning" and "this index was used to answer queries quickly".
>
> I think that's utter nonsense.

Well you probably know a bit more about the optimizer than I do. But I
can't see a case where the stats provided by the index would be useful
for choosing between two (or more) plans that don't use the index in the
actual query. If you're saying that there are such cases, then clearly
I don't know something, and my thinking is in the wrong here.

.marko

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