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This patch includes a lot of minor cleanups to the SGML documentation,

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including:

- replacing all the appropriate usages of <citetitle>PostgreSQL
...</citetitle> with &cite-user;, &cite-admin;, and so on

- fix an omission in the EXECUTE documentation

- add some more text to the EXPLAIN documentation

- improve the PL/PgSQL RETURN NEXT documentation (more work to do here)

- minor markup fixes


Neil Conway
This commit is contained in:
Bruce Momjian
2003-01-19 00:13:31 +00:00
parent 2042daf5c3
commit be2b660ecd
59 changed files with 562 additions and 474 deletions
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35
doc/src/sgml/ref/explain.sgml
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@@ -1,5 +1,5 @@
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/explain.sgml,v 1.21 2002/11/15 03:11:18 momjian Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/ref/explain.sgml,v 1.22 2003/01/19 00:13:29 momjian Exp $
PostgreSQL documentation
-->
@@ -87,9 +87,10 @@ EXPLAIN [ ANALYZE ] [ VERBOSE ] <replaceable class="PARAMETER">query</replaceabl
<note>
<para>
Prior to <productname>PostgreSQL</productname> 7.3, the query plan
was emitted in the form of a NOTICE message. Now it appears as a
query result (formatted like a table with a single text column).
Prior to <productname>PostgreSQL</productname> 7.3, the query
plan was emitted in the form of a <literal>NOTICE</literal>
message. Now it appears as a query result (formatted like a
table with a single text column).
</para>
</note>
</refsect2>
@@ -127,12 +128,26 @@ EXPLAIN [ ANALYZE ] [ VERBOSE ] <replaceable class="PARAMETER">query</replaceabl
costs to estimate which plan is really the cheapest.
</para>
<note>
<para>
In order to allow the <productname>PostgreSQL</productname> query
planner to make reasonably informed decisions when optimizing
queries, the <command>ANALYZE</command> statement should be used
to record statistics about the distribution of data within the
table. If you have not done this (or the statistical distribution
of the data in the table has changed significantly since the last
time <command>ANALYZE</command> was run), the estimated costs and
the resulting query plan displayed by <command>EXPLAIN</command>
are unlikely to conform to the real properties of the query.
</para>
</note>
<para>
The ANALYZE option causes the query to be actually executed, not only
planned. The total elapsed time expended within each plan node (in
milliseconds) and total number of rows it actually returned are added to
the display. This is useful for seeing whether the planner's estimates
are close to reality.
are close to the actual performance of the query.
</para>
<caution>
@@ -171,8 +186,7 @@ ROLLBACK;
<para>
There is only sparse documentation on the optimizer's use of cost
information in <productname>PostgreSQL</productname>.
Refer to the <citetitle>User's Guide</citetitle> and
<citetitle>Programmer's Guide</citetitle> for more information.
Refer to the &cite-user; and &cite-programmer; for more information.
</para>
</refsect2>
</refsect1>
@@ -233,7 +247,12 @@ EXPLAIN SELECT sum(i) FROM foo WHERE i &lt; 10;
<para>
Note that the specific numbers shown, and even the selected query
strategy, may vary between <productname>PostgreSQL</productname>
releases due to planner improvements.
releases due to planner improvements. In addition, the algorithm
used by <command>ANALYZE</command> to generate statistics is not
completely deterministic; therefore, it is possible (although not
likely) for cost estimations to change between runs of
<command>ANALYZE</command>, even if the actual distribution of data
in the table has not changed.
</para>
</refsect1>