postgres.git / summary / log / commit / refs

commit    26853a86ae4bc4f214005e05f55677e5b228f4f8
Author:   Alexander Korotkov <akorotkov@postgresql.org>
Date:     Fri Aug 10 11:14:36 2018 +0000
First released in: 12.0, 10.6, 11.0

    Add missing documentation for argument of amcostestimate()
    
    5262f7a4fc44 have introduced parallel index scan.  In order to estimate the
    number of parallel workers, it adds extra argument to amcostestimate() index
    access method API function.  However, this extra argument was missed in the
    documentation.  This commit fixes that.
    
    Discussion: https://postgr.es/m/4128fdb4-8b63-2e05-38f6-3125f8c27263%40lab.ntt.co.jp
    Author: Tatsuro Yamada, Alexander Korotkov
    Backpatch-through: 10


 doc/src/sgml/indexam.sgml | 22 +++++++++++++++++++---
 1 file 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>
 
@@ -1279,6 +1290,11 @@ amcostestimate (PlannerInfo *root,
    table.
   </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.


[parent: da1a5da1e421]