Re: [Tarantool-patches] [PATCH v2 1/1] sql: enable autoindex optimization

[Mergen Imeev <imeevma@tarantool.org>]

On 06.10.2020 13:44, Nikita Pettik wrote:
> On 06 Oct 10:08, imeevma@tarantool.org wrote:
>> This patch enables "autoindex" optimization. This optimization uses an
>> ephemeral space that contains all the fields used in the query. This
>> ephemeral space is called "autoindex". Autoindex may have fewer fields
>> than the original space, and the order of these fields in autoindex may
>> be different from their order in the original space. In addition to the
>> mentioned fields, autoindex contains a rowid.
>>
>> The primary key of autoindex is a covering index, i.e. it contains all
>> of its fields.
>>
>> Currently this optimization mainly used in cases when values SELECTED
>> from more than one space and WHERE specified.
>>
>> At the moment, this optimization does not take into account the number
>> of tuples in spaces. This should be fixed.
>>
>> Closes #4933
>>
>> Co-authored-by: Mergen Imeev <imeevma@gmail.com>
>> Co-authored-by: Timur Safin <tsafin@tarantool.org>
>> ---
>> https://github.com/tarantool/tarantool/issues/4933
>> https://github.com/tarantool/tarantool/tree/imeevma/gh-4933-autoindex
>>
>> @ChangeLog
>>   - "Auto-index" optimization is now enabled (gh-4933).
>> diff --git a/test/sql/misc.result b/test/sql/misc.result
>> index 6af11bfba..d86d55081 100644
>> --- a/test/sql/misc.result
>> +++ b/test/sql/misc.result
>> @@ -204,3 +204,32 @@ box.execute('SELECT field66, field68, field70 FROM test')
>>   box.space.TEST:drop()
>>   ---
>>   ...
>> +-- gh-4933: Make sure that autoindex optimization is used.
>> +box.execute('CREATE TABLE t1(i int primary key, a int);')
>> +---
>> +- row_count: 1
>> +...
>> +box.execute('CREATE TABLE t2(i int primary key, b int);')
>> +---
>> +- row_count: 1
>> +...
>> +--
>> +-- There is no need to insert values in the tables since planner assumes a
>> +-- default number of tuples for each space, regardless of how many tuples there
>> +-- actually are in those spaces. The default value is 1048576 (== 2^20).
>> +--
>> +box.execute('EXPLAIN QUERY PLAN SELECT a, b FROM t1, t2 WHERE a = b;')
>> +---
>> +- metadata:
>> +  - name: selectid
>> +    type: integer
>> +  - name: order
>> +    type: integer
>> +  - name: from
>> +    type: integer
>> +  - name: detail
>> +    type: text
>> +  rows:
>> +  - [0, 0, 0, 'SCAN TABLE T1 (~1048576 rows)']
>> +  - [0, 1, 1, 'SEARCH TABLE T2 USING AUTOMATIC COVERING INDEX (B=?) (~20 rows)']
>> +...
> I haven't reviewed the whole patch yet, but do you really think autoindex
> qp optimization deserves this single insignificant test..?
So, there won't be review before I create new tests?
>