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From: Valentin Kulichenko <valentin.kulichenko@gmail.com>
Date: Tue, 3 Jan 2017 11:59:09 -0800
Message-ID: <CABuYRcr541T4FM79uQt5u4K_MYxptc2UqGn8eU3B=rbVZsTd5w@mail.gmail.com>
Subject: min()/max() SQL and indexes
To: dev@ignite.apache.org, Sergi Vladykin <sergi.vladykin@gmail.com>
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archived-at: Tue, 03 Jan 2017 19:59:44 -0000

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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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