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Updates to backend flowchart

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Several languages and URL updates to various information in the
backend flowchart.

Author: Bruce Momjian <bruce@momjian.us>
This commit is contained in:
Jonathan S. Katz
2020-04-23 13:31:05 -04:00
parent a90cbd217e
commit 502447d1ad
1 changed files with 7 additions and 6 deletions
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13
templates/pages/developer/backend.html
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@ -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">transformWhereClause().</a>
href="https://git.postgresql.org/gitweb/?p=postgresql.git;a=blob;f=src/backend/parser/parse_clause.c">transformFromClause()</a> and
<a 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>