diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 28eb322f3f..99834e7286 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -21290,6 +21290,9 @@ postgres=# SELECT * FROM pg_walfile_name_offset(pg_stop_backup());
    <indexterm>
     <primary>pg_relation_size</primary>
    </indexterm>
+   <indexterm>
+    <primary>pg_relation_block_number</primary>
+   </indexterm>
    <indexterm>
     <primary>pg_size_bytes</primary>
    </indexterm>
@@ -21363,6 +21366,15 @@ postgres=# SELECT * FROM pg_walfile_name_offset(pg_stop_backup());
         Shorthand for <literal>pg_relation_size(..., 'main')</literal>
        </entry>
       </row>
+      <row>
+       <entry>
+        <literal><function>pg_relation_block_number(<parameter>relation</parameter> <type>regclass</type>)</function></literal>
+        </entry>
+       <entry><type>bigint</type></entry>
+       <entry>
+        Shorthand for <literal>pg_relation_block_number(..., 'main')</literal>
+       </entry>
+      </row>
       <row>
        <entry>
         <literal><function>pg_size_bytes(<type>text</type>)</function></literal>
@@ -21504,6 +21516,11 @@ postgres=# SELECT * FROM pg_walfile_name_offset(pg_stop_backup());
     </itemizedlist>
    </para>
 
+   <para>
+    <function>pg_relation_block_number</function> accepts the OID or name of a table
+    and returns the number of blocks of that relation.
+   </para>
+
    <para>
     <function>pg_size_pretty</function> can be used to format the result of one of
     the other functions in a human-readable way, using bytes, kB, MB, GB or TB
diff --git a/src/backend/utils/adt/dbsize.c b/src/backend/utils/adt/dbsize.c
index a87e7214e9..2462d65570 100644
--- a/src/backend/utils/adt/dbsize.c
+++ b/src/backend/utils/adt/dbsize.c
@@ -23,6 +23,7 @@
 #include "commands/tablespace.h"
 #include "miscadmin.h"
 #include "storage/fd.h"
+#include "storage/bufmgr.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/numeric.h"
@@ -335,6 +336,25 @@ pg_relation_size(PG_FUNCTION_ARGS)
 	PG_RETURN_INT64(size);
 }
 
+Datum
+pg_relation_block_number(PG_FUNCTION_ARGS)
+{
+	Oid			relOid = PG_GETARG_OID(0);
+	Relation	rel;
+	int64		size;
+
+	rel = try_relation_open(relOid, AccessShareLock);
+
+	if (rel == NULL)
+		PG_RETURN_NULL();
+
+	size = RelationGetNumberOfBlocks(rel);
+
+	relation_close(rel, AccessShareLock);
+
+	PG_RETURN_INT64(size);
+}
+
 /*
  * Calculate total on-disk size of a TOAST relation, including its indexes.
  * Must not be applied to non-TOAST relations.
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 58ea5b982b..b68a523d3b 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6929,6 +6929,10 @@
   descr => 'disk space usage for the specified fork of a table or index',
   proname => 'pg_relation_size', provolatile => 'v', prorettype => 'int8',
   proargtypes => 'regclass text', prosrc => 'pg_relation_size' },
+{ oid => '2228',
+  descr => 'total block number for the main fork of the specified table or index',
+  proname => 'pg_relation_block_number', provolatile => 'v', prorettype => 'int8',
+  proargtypes => 'regclass', prosrc => 'pg_relation_block_number' },
 { oid => '2286',
   descr => 'total disk space usage for the specified table and associated indexes',
   proname => 'pg_total_relation_size', provolatile => 'v', prorettype => 'int8',