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1 | 1 | <!--
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2 |
| -$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.118 2002/06/15 19:58:53 momjian Exp $ |
| 2 | +$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.119 2002/06/16 00:09:11 momjian Exp $ |
3 | 3 | -->
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4 | 4 |
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5 | 5 | <Chapter Id="runtime">
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@@ -759,34 +759,6 @@ env PGOPTIONS='-c geqo=off' psql
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759 | 759 | </listitem>
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760 | 760 | </varlistentry>
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761 | 761 |
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| - <varlistentry> |
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| - <term><varname>KSQO</varname> (<type>boolean</type>)</term> |
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| - <listitem> |
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| - <para> |
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| - The <firstterm>Key Set Query Optimizer</firstterm> |
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| - (<acronym>KSQO</acronym>) causes the query planner to convert |
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| - queries whose <literal>WHERE</> clause contains many OR'ed AND |
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| - clauses (such as <literal>WHERE (a=1 AND b=2) OR (a=2 AND b=3) |
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| - ...</literal>) into a union query. This method can be faster |
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| - than the default implementation, but it doesn't necessarily give |
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| - exactly the same results, since <literal>UNION</> implicitly |
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| - adds a <literal>SELECT DISTINCT</> clause to eliminate identical |
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| - output rows. <acronym>KSQO</acronym> is commonly used when |
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| - working with products like <productname>Microsoft |
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| - Access</productname>, which tend to generate queries of this |
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| - form. |
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| - </para> |
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| - |
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| - <para> |
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| - The <acronym>KSQO</acronym> algorithm used to be absolutely |
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| - essential for queries with many OR'ed AND clauses, but in |
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| - <productname>PostgreSQL</productname> 7.0 and later the standard |
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| - planner handles these queries fairly successfully; hence the |
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| - default is off. |
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| - </para> |
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| - </listitem> |
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| - </varlistentry> |
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| - |
790 | 762 | <varlistentry>
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791 | 763 | <term><varname>RANDOM_PAGE_COST</varname> (<type>floating point</type>)</term>
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792 | 764 | <listitem>
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