Re: Using indices for UNION.

From: Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>
To: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Using indices for UNION.
Date: 2014-01-14 09:16:20
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Sorry, I missed to attach file.

> This is cont'd from CF3.
> The issue in brief is that UNION is never flattened differently
> to UNION ALL so UNION cannot make use of index scan even if
> usable.
> This patch flattens UNION likewise currently did for UNION ALL.
> This patch needs another 'UNION ALL' patch and further gain with
> even another 'Widening application of indices' patch. ('Ready for
> Commit' now in CF3..)
> You can see the detailed outlines in the message at here,
> The attached patche is rebased to current 9.4dev HEAD and make
> check at the topmost directory and src/test/isolation are passed
> without error.


Kyotaro Horiguchi
NTT Open Source Software Center

Attachment Content-Type Size
union_uses_idx_v2_20140114.patch text/x-patch 6.7 KB

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