1 files changed, 16 insertions, 14 deletions
diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 1431d2649be..939d3fe2739 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -104,7 +104,6 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
   GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="parameter">index_parameters</replaceable> |
-  COMPRESSION <replaceable class="parameter">compression_method</replaceable> |
   REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -391,24 +390,27 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </term>
     <listitem>
      <para>
-      This sets the compression method to be used for data inserted into a column.
-
+      This form sets the compression method for a column, determining how
+      values inserted in future will be compressed (if the storage mode
+      permits compression at all).
       This does not cause the table to be rewritten, so existing data may still
       be compressed with other compression methods.  If the table is rewritten with
       <command>VACUUM FULL</command> or <command>CLUSTER</command>, or restored
-      with <application>pg_restore</application>, then all tuples are rewritten
-      with the configured compression methods.
-
-      Also, note that when data is inserted from another relation (for example,
-      by <command>INSERT ... SELECT</command>), tuples from the source data are
-      not necessarily detoasted, and any previously compressed data is retained
-      with its existing compression method, rather than recompressing with the
-      compression methods of the target columns.
-
+      with <application>pg_restore</application>, then all values are rewritten
+      with the configured compression method.
+      However, when data is inserted from another relation (for example,
+      by <command>INSERT ... SELECT</command>), values from the source table are
+      not necessarily detoasted, so any previously compressed data may retain
+      its existing compression method, rather than being recompressed with the
+      compression method of the target column.
       The supported compression
       methods are <literal>pglz</literal> and <literal>lz4</literal>.
-      <literal>lz4</literal> is available only if <literal>--with-lz4</literal>
-      was used when building <productname>PostgreSQL</productname>.
+      (<literal>lz4</literal> is available only if <option>--with-lz4</option>
+      was used when building <productname>PostgreSQL</productname>.)  In
+      addition, <replaceable class="parameter">compression_method</replaceable>
+      can be <literal>default</literal>, which selects the default behavior of
+      consulting the <xref linkend="guc-default-toast-compression"/> setting
+      at the time of data insertion to determine the method to use.
      </para>
     </listitem>
    </varlistentry>