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From Sergi Vladykin <sergi.vlady...@gmail.com>
Subject Re: min()/max() SQL and indexes
Date Wed, 04 Jan 2017 11:11:31 GMT
Our indexes do not support this optimization right now.

It is not that hard to implement it, I'd suggest to plan it for
2.0+PageMemory, because otherwise we'll have to implement it twice with
conflicts.

Sergi



2017-01-03 22:59 GMT+03:00 Valentin Kulichenko <
valentin.kulichenko@gmail.com>:

> Folks,
>
> Does anyone know if index is supposed to be used when a query like below
> is executed?
>
> select min(id) from MyValue
> select max(id) from MyValue
>
> I tried it and execution time doesn't seem to depend on whether I create
> an index for 'id' field or not. It always takes around 2 seconds with only
> 5,000,000 records on a single node. Result is the same for min() and max(),
> so index order doesn't seem to have affect either.
>
> Execution plan shows that index is used though:
>
> SELECT
>     MAX(ID) AS __C0
> FROM "test".MYVALUE
>     /* "test"."id_idx" */
>
> SELECT
>     MAX(__C0) AS __C0
> FROM PUBLIC.__T0
>     /* "test"."merge_scan" */
>
> Sergi, can you please clarify what is the expected behavior here?
>
> -Val
>

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