diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index c809ff1ba4..ae5d9a0226 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -5724,8 +5724,10 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i
         <returnvalue>bigint</returnvalue>
        </para>
        <para>
-        Returns the number of buffers fetched for table or index, in the current
-        transaction.
+        Returns the number of block read requests for table or index, in the
+        current transaction. This number minus <function>
+        pg_stat_get_xact_blocks_hit</function> gives the number of kernel
+        <function>read()</function> calls.
        </para></entry>
       </row>
 
@@ -5738,8 +5740,9 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i
         <returnvalue>bigint</returnvalue>
        </para>
        <para>
-        Returns the number of buffer hits for table or index, in the current
-        transaction.
+        Returns the number of block read requests for table or index, in the
+        current transaction, found in cache (not triggering kernel
+        <function>read()</function> calls).
        </para></entry>
       </row>