pg.ddx.io pgsql-docs@postgresql.org mailing list archive help / color / mirror / Atom feed From: Bruce Momjian <bruce@momjian.us>
To: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Marc Rechté <marc4@rechte.fr>
Cc: PostgreSQL www <pgsql-www@postgresql.org>
Subject: Re: Backend Flowchart / Developer doc
Date: Thu, 23 Apr 2020 13:06:26 -0400
Message-ID: <20200423170626.GB4210@momjian.us> (raw )
In-Reply-To: <20200421153109.GD19613@momjian.us >
References: <f22d0dc9-07a6-5526-625a-3bc349639286@rechte.fr >
<20200416151729.GA9284@alvherre.pgsql >
<20200421153109.GD19613@momjian.us >
Thread moved to www for patch application. Please apply the attached
patch to update the text of the backend flowchart. Thanks.
---------------------------------------------------------------------------
On Tue, Apr 21, 2020 at 11:31:09AM -0400, Bruce Momjian wrote:
> On Thu, Apr 16, 2020 at 11:17:29AM -0400, Alvaro Herrera wrote:
> > On 2020-Apr-15, Marc Rechté wrote:
> >
> > > Hello,
> > >
> > > Don't know if this the correct list to submit this issue.
> > >
> > > On the https://www.postgresql.org/developer/backend/ , it mentions a
> > > Query.qual field which does not exist in the Query structure.
> >
> > I think that diagram (and the accompanying wiki page) requires a *lot*
> > of more significant updating than just that field. It is wildly
> > outdated.
>
> I developed the attached patch to fix the items I saw needed updating.
--
Bruce Momjian <bruce@momjian.us> https://momjian.us
EnterpriseDB https://enterprisedb.com
+ As you are, so once was I. As I am, so you will be. +
+ Ancient Roman grave inscription +
Attachments:
backend.diff (text/x-diff, 2.7K) download
diff --git a/templates/pages/developer/backend.html b/templates/pages/developer/backend.html
index ab7e5d6..7337a07 100644
--- a/templates/pages/developer/backend.html
+++ b/templates/pages/developer/backend.html
@@ -56,7 +56,7 @@ or <a
href="https://git.postgresql.org/gitweb/?p=postgresql.git;a=blob;f=src/include/nodes/parsenodes.h">SelectStmt.</a></p>
<p>The statement is then identified as complex (<em>SELECT / INSERT /
-UPDATE / DELETE</em>) or simple, e.g <em>CREATE USER, ANALYZE,</em>
+UPDATE / DELETE</em>) or simple, e.g <em>CREATE ROLE, ANALYZE,</em>
etc. Simple utility commands that do not require the executor are processed by statement-specific
functions in the <a href="https://wiki.postgresql.org/wiki/Backend_flowchart#commands">commands</a> module.
Complex statements require more handling.</p>
@@ -64,11 +64,12 @@ Complex statements require more handling.</p>
<p>The parser takes a complex query, and creates a <a
href="https://git.postgresql.org/gitweb/?p=postgresql.git;a=blob;f=src/include/nodes/parsenodes.h">Query</a>
structure that contains all the elements used by complex queries.
-Query.qual holds the <em>WHERE</em> clause qualification, which is filled
+Query.jointree holds the <em>FROM</em> and <em>WHERE</em> clauses, which is filled
in by <a
+href="https://git.postgresql.org/gitweb/?p=postgresql.git;a=blob;f=src/backend/parser/parse_clause.c">transformFromClause()</a> and
href="https://git.postgresql.org/gitweb/?p=postgresql.git;a=blob;f=src/backend/parser/parse_clause.c">transformWhereClause().</a>
Each table referenced in the query is represented by a <a
-href="https://git.postgresql.org/gitweb/?p=postgresql.git;a=blob;f=src/include/nodes/parsenodes.h">RangeTableEntry,</a>
+href="https://git.postgresql.org/gitweb/?p=postgresql.git;a=blob;f=src/include/nodes/parsenodes.h">RangeTblEntry,</a>
and they are linked together to form the <em>range table</em> of the
query, which is generated by <a
href="https://git.postgresql.org/gitweb/?p=postgresql.git;a=blob;f=src/backend/parser/parse_clause.c">transformFromClause().</a>
@@ -95,8 +96,8 @@ system.</p>
<p>The <a
href="https://wiki.postgresql.org/wiki/Backend_flowchart#optimizer_path">optimizer</a>
uses the Query structure to determine the best table join order and join
-type of each table in the RangeTable, using Query.qual(<em>WHERE</em>
-clause) to consider optimal index usage.</p> The <a
+type of each table in the RangeTable, using Query.jointree(<em>FROM</em>
+and <em>WHERE</em> clauses) to consider optimal index usage.</p> The <a
href="https://wiki.postgresql.org/wiki/Backend_flowchart#optimizer_path">path</a>
module then generates an optimal <a
href="https://git.postgresql.org/gitweb/?p=postgresql.git;a=blob;f=src/include/nodes/plannodes.h">Plan,</a>
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To: pgsql-docs@postgresql.org
Cc: bruce@momjian.us, alvherre@2ndquadrant.com, marc4@rechte.fr, pgsql-www@postgresql.org
Subject: Re: Backend Flowchart / Developer doc
In-Reply-To: <20200423170626.GB4210@momjian.us>
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