2 files changed, 22 insertions, 1 deletions
diff --git a/doc/src/sgml/indexam.sgml b/doc/src/sgml/indexam.sgml
index b68daa55aeb..76ac0fcddd7 100644
--- a/doc/src/sgml/indexam.sgml
+++ b/doc/src/sgml/indexam.sgml
@@ -809,7 +809,8 @@ amrestrpos (IndexScanDesc scan);
   <para>
 <programlisting>
 Size
-amestimateparallelscan (void);
+amestimateparallelscan (int nkeys,
+                        int norderbys);
 </programlisting>
    Estimate and return the number of bytes of dynamic shared memory which
    the access method will be needed to perform a parallel scan.  (This number
@@ -818,6 +819,13 @@ amestimateparallelscan (void);
   </para>
 
   <para>
+   The <literal>nkeys</literal> and <literal>norderbys</literal>
+   parameters indicate the number of quals and ordering operators that will be
+   used in the scan; the same values will be passed to <function>amrescan</function>.
+   Note that the actual values of the scan keys aren't provided yet.
+  </para>
+
+  <para>
    It is not necessary to implement this function for access methods which
    do not support parallel scans or for which the number of additional bytes
    of storage required is zero.
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index e1e96ba7c45..053da8d6e40 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -4064,6 +4064,19 @@ description | Waiting for a newly initialized WAL file to reach durable storage
    </para>
   </note>
 
+  <note>
+   <para>
+    Queries that use certain <acronym>SQL</acronym> constructs to search for
+    rows matching any value out of a list or array of multiple scalar values
+    (see <xref linkend="functions-comparisons"/>) perform multiple
+    <quote>primitive</quote> index scans (up to one primitive scan per scalar
+    value) during query execution.  Each internal primitive index scan
+    increments <structname>pg_stat_all_indexes</structname>.<structfield>idx_scan</structfield>,
+    so it's possible for the count of index scans to significantly exceed the
+    total number of index scan executor node executions.
+   </para>
+  </note>
+
  </sect2>
 
  <sect2 id="monitoring-pg-statio-all-tables-view">