From 448b02c00515ba9d6683a8a97fe4305604d80028 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Thu, 6 May 2021 08:27:20 -0400
Subject: [PATCH] Additional doc fixes for configurable TOAST compression.

The grammar changes in commit bbe0a81db69bd10bd166907c3701492a29aca294
allow SET COMPRESSION to be used with ALTER MATERIALIZED VIEW as
well as with ALTER TABLE, so update those docs to say that it works.

Also, update the documentation for the pg_column_compression()
to explain that it will return NULL when there's no relevant value.

Patch by me, per concerns from Michael Paquier.

Discussion: http://postgr.es/m/CA+Tgmob9h5u4iNL9KM0drZgkY-JL4oCVW0dWrMqtLPQ1zHkquA@mail.gmail.com
---
 doc/src/sgml/func.sgml                        | 3 ++-
 doc/src/sgml/ref/alter_materialized_view.sgml | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index c60d98360ff..0b5571460de 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -26256,7 +26256,8 @@ postgres=# SELECT * FROM pg_walfile_name_offset(pg_stop_backup());
        </para>
        <para>
         Shows the compression algorithm that was used to compress a
-        an individual variable-length value.
+        an individual variable-length value. Returns <literal>NULL</literal>
+        if the value is not compressed.
        </para></entry>
       </row>
 
diff --git a/doc/src/sgml/ref/alter_materialized_view.sgml b/doc/src/sgml/ref/alter_materialized_view.sgml
index 27f60f6df59..7011a0e7da0 100644
--- a/doc/src/sgml/ref/alter_materialized_view.sgml
+++ b/doc/src/sgml/ref/alter_materialized_view.sgml
@@ -40,6 +40,7 @@ ALTER MATERIALIZED VIEW ALL IN TABLESPACE <replaceable class="parameter">name</ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET ( <replaceable class="parameter">attribute_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> RESET ( <replaceable class="parameter">attribute_option</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }
+    ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
     CLUSTER ON <replaceable class="parameter">index_name</replaceable>
     SET WITHOUT CLUSTER
     SET ( <replaceable class="parameter">storage_parameter</replaceable> [= <replaceable class="parameter">value</replaceable>] [, ... ] )
-- 
2.39.5