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@ -1,5 +1,5 @@ |
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<!-- |
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<!-- |
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$PostgreSQL: pgsql/doc/src/sgml/ref/prepare.sgml,v 1.9 2003/12/01 22:07:58 momjian Exp $ |
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$PostgreSQL: pgsql/doc/src/sgml/ref/prepare.sgml,v 1.10 2003/12/14 00:55:46 neilc Exp $ |
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PostgreSQL documentation |
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PostgreSQL documentation |
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--> |
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--> |
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@ -52,7 +52,7 @@ PREPARE <replaceable class="PARAMETER">plan_name</replaceable> [ (<replaceable c |
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</para> |
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</para> |
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<para> |
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<para> |
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Prepared statements are only for the duration of the current |
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Prepared statements only last for the duration of the current |
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database session. When the session ends, the prepared statement is |
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database session. When the session ends, the prepared statement is |
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forgotten, so it must be recreated before being used again. This |
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forgotten, so it must be recreated before being used again. This |
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also means that a single prepared statement cannot be used by |
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also means that a single prepared statement cannot be used by |
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@ -115,12 +115,12 @@ PREPARE <replaceable class="PARAMETER">plan_name</replaceable> [ (<replaceable c |
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<title>Notes</title> |
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<title>Notes</title> |
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<para> |
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<para> |
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In some situations, the query plan produced by for a prepared |
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In some situations, the query plan produced for a prepared |
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statement may be inferior to the plan produced if the statement |
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statement will be inferior to the query plan that would have been |
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were submitted and executed normally. This is because when the |
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chosen if the statement had been submitted and executed |
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statement is planned and the planner attempts to determine the |
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normally. This is because when the statement is planned and the |
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optimal query plan, the actual values of any parameters specified |
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planner attempts to determine the optimal query plan, the actual |
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in the statement are |
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values of any parameters specified in the statement are |
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unavailable. <productname>PostgreSQL</productname> collects |
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unavailable. <productname>PostgreSQL</productname> collects |
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statistics on the distribution of data in the table, and can use |
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statistics on the distribution of data in the table, and can use |
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constant values in a statement to make guesses about the likely |
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constant values in a statement to make guesses about the likely |
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