Horton

Re: WIP: Covering + unique indexes.

David Rowley <david.rowley@2ndquadrant.com>

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From: David Rowley <david.rowley@2ndquadrant.com>
To: Anastasia Lubennikova <a.lubennikova@postgrespro.ru>
Cc: Jeff Janes <jeff.janes@gmail.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2016-01-13T19:24:19Z
Lists: pgsql-hackers 
On 14 January 2016 at 02:58, Anastasia Lubennikova <
a.lubennikova@postgrespro.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

Commits

  1. Adjust INCLUDE index truncation comments and code.

  2. Add commentary explaining why MaxIndexTuplesPerPage calculation is safe.

  3. Indexes with INCLUDE columns and their support in B-tree

  4. Add amcheck verification of heap relations belonging to btree indexes.

  5. Doc: move info for btree opclass implementors into main documentation.

  6. Doc: mention that you can't PREPARE TRANSACTION after NOTIFY.

  7. Remove dedicated B-tree root-split record types.

  8. Restructure index access method API to hide most of it at the C level.

  9. Split _bt_insertonpg to two functions.

  10. Major overhaul of btree index code. Eliminate special BTP_CHAIN logic for