doc: Clarify BUFFERS behavior without ANALYZE in EXPLAIN

This commit clarifies the documentation for the BUFFERS option of EXPLAIN
by explicitly describing its behavior when ANALYZE is not specified.

Author: Ryo Matsumura <matsumura.ryo@fujitsu.com>
Reviewed-by: Fujii Masao <masao.fujii@gmail.com>
Discussion: https://postgr.es/m/TYRPR01MB13457D31085CB5B246DBBA1AFE845A@TYRPR01MB13457.jpnprd01.prod.outlook.com

diff --git a/doc/src/sgml/ref/explain.sgml b/doc/src/sgml/ref/explain.sgml
index 7dee77fd366b0693d82bddf107c733654011150d..5b8b521802ee5ece437aaefad978ae1c54d422c0 100644 (file)
--- a/doc/src/sgml/ref/explain.sgml
+++ b/doc/src/sgml/ref/explain.sgml
@@ -202,7 +202,10 @@ ROLLBACK;
       The number of blocks shown for an
       upper-level node includes those used by all its child nodes.  In text
       format, only non-zero values are printed.  Buffers information is
-      automatically included when <literal>ANALYZE</literal> is used.
+      included by default when <literal>ANALYZE</literal> is used but
+      otherwise is not included by default.  When this parameter is
+      <literal>TRUE</literal> without <literal>ANALYZE</literal>,
+      only buffer usage during the query planning phase is reported.
      </para>
     </listitem>
    </varlistentry>