doc: Fix column_name parameter in ALTER MATERIALIZED VIEW

Parameter column_name must be an existing column because ALTER
MATERIALIZED VIEW cannot add new columns.  The old description was
likely copied from ALTER TABLE.

Author: Erik Wienhold
Discussion: https://postgr.es/m/6880ca53-7961-4eeb-86d5-6bd05fc2027e@ewie.name
Backpatch-through: 12

diff --git a/doc/src/sgml/ref/alter_materialized_view.sgml b/doc/src/sgml/ref/alter_materialized_view.sgml
index da7ed045974f4ffadde0ea6489e56b6e8e93dce5..f81a7393f5d2f4bb9b958f0218d45affa3cf9bef 100644 (file)
--- a/doc/src/sgml/ref/alter_materialized_view.sgml
+++ b/doc/src/sgml/ref/alter_materialized_view.sgml
@@ -100,7 +100,7 @@ ALTER MATERIALIZED VIEW ALL IN TABLESPACE name
      column_name
      
       
-       Name of a new or existing column.
+       Name of an existing column.