3 files changed, 49 insertions, 7 deletions
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index e7d408824e2..a189a8efc3f 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -1882,6 +1882,31 @@ include_dir 'conf.d'
      </note>
     </sect2>
 
+    <sect2 id="runtime-config-index-vacuum">
+     <title>Index Vacuum</title>
+     <variablelist>
+     <varlistentry id="guc-vacuum-cleanup-index-scale-factor" xreflabel="vacuum_cleanup_index_scale_factor">
+      <term><varname>vacuum_cleanup_index_scale_factor</varname> (<type>floating point</type>)
+      <indexterm>
+       <primary><varname>vacuum_cleanup_index_scale_factor</varname> configuration parameter</primary>
+      </indexterm>
+      </term>
+      <listitem>
+       <para>
+        When no tuples were deleted from the heap, B-tree indexes might still
+        be scanned during <command>VACUUM</command> cleanup stage by two
+        reasons.  The first reason is that B-tree index contains deleted pages
+        which can be recycled during cleanup.  The second reason is that B-tree
+        index statistics is stalled.  The criterion of stalled index statistics
+        is number of inserted tuples since previous statistics collection
+        is greater than <varname>vacuum_cleanup_index_scale_factor</varname>
+        fraction of total number of heap tuples.
+       </para>
+      </listitem>
+     </varlistentry>
+     </variablelist>
+    </sect2>
+
     <sect2 id="runtime-config-resource-background-writer">
      <title>Background Writer</title>
 
diff --git a/doc/src/sgml/pageinspect.sgml b/doc/src/sgml/pageinspect.sgml
index 23570af4bf8..4d5da186bb4 100644
--- a/doc/src/sgml/pageinspect.sgml
+++ b/doc/src/sgml/pageinspect.sgml
@@ -247,13 +247,15 @@ test=# SELECT * FROM heap_page_item_attrs(get_raw_page('pg_class', 0), 'pg_class
       index's metapage.  For example:
 <screen>
 test=# SELECT * FROM bt_metap('pg_cast_oid_index');
--[ RECORD 1 ]-----
-magic     | 340322
-version   | 2
-root      | 1
-level     | 0
-fastroot  | 1
-fastlevel | 0
+-[ RECORD 1 ]-----------+-------
+magic                   | 340322
+version                 | 3
+root                    | 1
+level                   | 0
+fastroot                | 1
+fastlevel               | 0
+oldest_xact             | 582
+last_cleanup_num_tuples | 1000
 </screen>
      </para>
     </listitem>
diff --git a/doc/src/sgml/ref/create_index.sgml b/doc/src/sgml/ref/create_index.sgml
index ba1c5d63925..e9521fbfb91 100644
--- a/doc/src/sgml/ref/create_index.sgml
+++ b/doc/src/sgml/ref/create_index.sgml
@@ -370,6 +370,21 @@ CREATE [ UNIQUE ] INDEX [ CONCURRENTLY ] [ [ IF NOT EXISTS ] <replaceable class=
    </variablelist>
 
    <para>
+    B-tree indexes additionally accept this parameter:
+   </para>
+
+   <variablelist>
+   <varlistentry>
+    <term><literal>vacuum_cleanup_index_scale_factor</literal></term>
+    <listitem>
+    <para>
+      Per-table value for <xref linkend="guc-vacuum-cleanup-index-scale-factor"/>.
+    </para>
+    </listitem>
+   </varlistentry>
+   </variablelist>
+
+   <para>
     GiST indexes additionally accept this parameter:
    </para>