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1 | 1 | <!-- |
2 | | -$PostgreSQL: pgsql/doc/src/sgml/ref/explain.sgml,v 1.35 2005/01/04 00:39:53 tgl Exp $ |
| 2 | +$PostgreSQL: pgsql/doc/src/sgml/ref/explain.sgml,v 1.36 2006/01/20 16:41:55 momjian Exp $ |
3 | 3 | PostgreSQL documentation |
4 | 4 | --> |
5 | 5 |
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@@ -151,11 +151,13 @@ ROLLBACK; |
151 | 151 | </para> |
152 | 152 |
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153 | 153 | <para> |
154 | | - Prior to <productname>PostgreSQL</productname> 7.3, the plan was |
155 | | - emitted in the form of a <literal>NOTICE</literal> message. Now it |
156 | | - appears as a query result (formatted like a table with a single |
157 | | - text column). |
| 154 | + Genetic query optimization (<acronym>GEQO</acronym>) randomly |
| 155 | + tests execution plans. Therefore, when the number of tables exceeds |
| 156 | + <varname>geqo_threshold</> causing genetic query optimization to be |
| 157 | + used, the execution plan is likely to change each time the statement |
| 158 | + is executed. |
158 | 159 | </para> |
| 160 | + |
159 | 161 | </refsect1> |
160 | 162 |
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161 | 163 | <refsect1> |
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