|
1 | 1 | <!-- |
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 | --> |
4 | 4 |
|
5 | 5 | <Chapter Id="runtime"> |
@@ -759,34 +759,6 @@ env PGOPTIONS='-c geqo=off' psql |
759 | 759 | </listitem> |
760 | 760 | </varlistentry> |
761 | 761 |
|
762 | | - <varlistentry> |
763 | | - <term><varname>KSQO</varname> (<type>boolean</type>)</term> |
764 | | - <listitem> |
765 | | - <para> |
766 | | - The <firstterm>Key Set Query Optimizer</firstterm> |
767 | | - (<acronym>KSQO</acronym>) causes the query planner to convert |
768 | | - queries whose <literal>WHERE</> clause contains many OR'ed AND |
769 | | - clauses (such as <literal>WHERE (a=1 AND b=2) OR (a=2 AND b=3) |
770 | | - ...</literal>) into a union query. This method can be faster |
771 | | - than the default implementation, but it doesn't necessarily give |
772 | | - exactly the same results, since <literal>UNION</> implicitly |
773 | | - adds a <literal>SELECT DISTINCT</> clause to eliminate identical |
774 | | - output rows. <acronym>KSQO</acronym> is commonly used when |
775 | | - working with products like <productname>Microsoft |
776 | | - Access</productname>, which tend to generate queries of this |
777 | | - form. |
778 | | - </para> |
779 | | - |
780 | | - <para> |
781 | | - The <acronym>KSQO</acronym> algorithm used to be absolutely |
782 | | - essential for queries with many OR'ed AND clauses, but in |
783 | | - <productname>PostgreSQL</productname> 7.0 and later the standard |
784 | | - planner handles these queries fairly successfully; hence the |
785 | | - default is off. |
786 | | - </para> |
787 | | - </listitem> |
788 | | - </varlistentry> |
789 | | - |
790 | 762 | <varlistentry> |
791 | 763 | <term><varname>RANDOM_PAGE_COST</varname> (<type>floating point</type>)</term> |
792 | 764 | <listitem> |
|