diff options
| -rw-r--r-- | doc/src/sgml/indexam.sgml | 22 |
1 files changed, 19 insertions, 3 deletions
diff --git a/doc/src/sgml/indexam.sgml b/doc/src/sgml/indexam.sgml index aa3d371d2e3..8b2999e41c5 100644 --- a/doc/src/sgml/indexam.sgml +++ b/doc/src/sgml/indexam.sgml @@ -383,7 +383,8 @@ amcostestimate (PlannerInfo *root, Cost *indexStartupCost, Cost *indexTotalCost, Selectivity *indexSelectivity, - double *indexCorrelation); + double *indexCorrelation, + double *indexPages); </programlisting> Estimate the costs of an index scan. This function is described fully in <xref linkend="index-cost-estimation">, below. @@ -1151,7 +1152,8 @@ amcostestimate (PlannerInfo *root, Cost *indexStartupCost, Cost *indexTotalCost, Selectivity *indexSelectivity, - double *indexCorrelation); + double *indexCorrelation, + double *indexPages); </programlisting> The first three parameters are inputs: @@ -1193,7 +1195,7 @@ amcostestimate (PlannerInfo *root, </para> <para> - The last four parameters are pass-by-reference outputs: + The last five parameters are pass-by-reference outputs: <variablelist> <varlistentry> @@ -1232,6 +1234,15 @@ amcostestimate (PlannerInfo *root, </para> </listitem> </varlistentry> + + <varlistentry> + <term><parameter>*indexPages</parameter></term> + <listitem> + <para> + Set to number of index leaf pages + </para> + </listitem> + </varlistentry> </variablelist> </para> @@ -1280,6 +1291,11 @@ amcostestimate (PlannerInfo *root, </para> <para> + The <parameter>indexPages</parameter> should be set to the number of leaf pages. + This is used to estimate the number of workers for parallel index scan. + </para> + + <para> When <parameter>loop_count</> is greater than one, the returned numbers should be averages expected for any one scan of the index. </para> |