From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp53.i.mail.ru (smtp53.i.mail.ru [94.100.177.113]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dev.tarantool.org (Postfix) with ESMTPS id 7F3C7469719 for ; Tue, 6 Oct 2020 14:00:49 +0300 (MSK) Date: Tue, 6 Oct 2020 14:00:45 +0300 From: Mergen Imeev Message-ID: <20201006110045.GA116791@tarantool.org> References: <38490e796033c2eb51ae9fec9e330f6bc7ec51a7.1601967922.git.imeevma@gmail.com> <20201006104440.GB12999@tarantool.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20201006104440.GB12999@tarantool.org> Subject: Re: [Tarantool-patches] [PATCH v2 1/1] sql: enable autoindex optimization List-Id: Tarantool development patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Nikita Pettik Cc: Mergen Imeev , tarantool-patches@dev.tarantool.org Hi! My answer below. On Tue, Oct 06, 2020 at 10:44:40AM +0000, 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 > > Co-authored-by: Timur Safin > > --- > > 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..? > The main test is TPC-H Q13, Q17 and Q20. Here we show that the optimization is enabled.