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体验新版 GitCode,发现更多精彩内容 >>
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b05204ac
编写于
1月 12, 2003
作者:
T
Tom Lane
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差异文件
Fix some minor grammatical errors.
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doc/src/sgml/perform.sgml
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doc/src/sgml/perform.sgml
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<!--
$Header: /cvsroot/pgsql/doc/src/sgml/perform.sgml,v 1.2
2 2002/11/11 20:14:03 petere
Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/perform.sgml,v 1.2
3 2003/01/12 18:42:59 tgl
Exp $
-->
<chapter id="performance-tips">
...
...
@@ -600,7 +600,7 @@ SELECT * FROM a, b, c WHERE a.id = b.id AND b.ref = c.id;
SELECT * FROM a CROSS JOIN b CROSS JOIN c WHERE a.id = b.id AND b.ref = c.id;
SELECT * FROM a JOIN (b JOIN c ON (b.ref = c.id)) ON (a.id = b.id);
</programlisting>
but
the second and third take less time to plan than the first. This effect
the second and third take less time to plan than the first. This effect
is not worth worrying about for only three tables, but it can be a
lifesaver with many tables.
</para>
...
...
@@ -628,8 +628,8 @@ SELECT * FROM d LEFT JOIN
(SELECT * FROM a, b, c WHERE ...) AS ss
ON (...);
</programlisting>
Here, joining D must be the last step in the query plan, but the
planner is free to consider various join orders for A, B, C.
Here, joining
to
D must be the last step in the query plan, but the
planner is free to consider various join orders for A, B,
and
C.
</para>
<para>
...
...
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