From: | David Rowley <david(dot)rowley(at)2ndquadrant(dot)com> |
---|---|
To: | Anastasia Lubennikova <a(dot)lubennikova(at)postgrespro(dot)ru> |
Cc: | Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: WIP: Covering + unique indexes. |
Date: | 2016-01-13 19:24:19 |
Message-ID: | CAKJS1f8Fbd69Y0qONSkn9q7-2VhzDVhodFXKdNiPDdpRO0p35A@mail.gmail.com |
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On 14 January 2016 at 02:58, Anastasia Lubennikova <
a(dot)lubennikova(at)postgrespro(dot)ru> wrote:
> 13.01.2016 04:27, David Rowley:
>
>> I've also done some testing:
>>
>> create table ab (a int, b int);
>> insert into ab select a,b from generate_Series(1,10) a(a),
>> generate_series(1,10000) b(b);
>> set enable_bitmapscan=off;
>> set enable_indexscan=off;
>>
>> select * from ab where a = 1 and b=1;
>> a | b
>> ---+---
>> 1 | 1
>> (1 row)
>>
>> set enable_indexscan = on;
>> select * from ab where a = 1 and b=1;
>> a | b
>> ---+---
>> (0 rows)
>>
>> This is broken. I've not looked into why yet, but from looking at the
>> EXPLAIN output I was a bit surprised to see b=1 as an index condition. I'd
>> have expected a Filter maybe, but I've not looked at the EXPLAIN code to
>> see how those are determined yet.
>>
>
> Hmm... Do you use both patches?
> And could you provide index definition, I can't reproduce the problem
> assuming that index is created by the statement
> CREATE INDEX idx ON ab (a) INCLUDING (b);
Sorry, I forgot the index, and yes you guessed correctly about that.
The problem only exists without the omit_opclass_4.0.patch and with the
covering_unique_4.0.patch, so please ignore.
I will try to review the omit_opclass_4.0.patch soon.
David
--
David Rowley http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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