doc: Mention validation attempt during ALTER INDEX .. ATTACH PARTITION

Since 9d3e094f12, the command tries to validate the parent index of the
named index, if invalid.  The documentation did not mention this
behavior, which could be confusing.

Author: Mohamed ALi <moali.pg@gmail.com>
Discussion: https://postgr.es/m/CAGnOmWpHu25_LpT=zv7KtetQhqV1QEZzFYLd_TDyOLu1Od9fpw@mail.gmail.com
Backpatch-through: 14

diff --git a/doc/src/sgml/ref/alter_index.sgml b/doc/src/sgml/ref/alter_index.sgml
index 1d42d05d8581625ee46bd5c58ba149bf5d41bfc4..fb7096c16ea64685292b7599829dd227c096f07f 100644 (file)
--- a/doc/src/sgml/ref/alter_index.sgml
+++ b/doc/src/sgml/ref/alter_index.sgml
@@ -97,6 +97,11 @@ ALTER INDEX ALL IN TABLESPACE <replaceable class="parameter">name</replaceable>
       index cannot be dropped by itself, and will automatically be dropped
       if its parent index is dropped.
      </para>
+     <para>
+      If the named index is already attached to the altered index, the
+      command will attempt to validate the parent index if the parent is
+      currently invalid.
+     </para>
     </listitem>
    </varlistentry>