Doc: in v12 release notes, explain how to replace uses of consrc and adsrc.

While you can find that info if you drill down far enough, it seems more
helpful to put something right in the compatibility notes.  Per a question
from Ivan Sergio Borgonovo.

Discussion: https://postgr.es/m/a6359855-2a5e-a56c-ebba-4ea46a1f0ebe@webthatworks.it

diff --git a/doc/src/sgml/release-12.sgml b/doc/src/sgml/release-12.sgml
index 68949b2026652bac0c4ccc855d859088743c44aa..dfa3851913cf2954a2b126a8525dd973e0df2fc7 100644 (file)
--- a/doc/src/sgml/release-12.sgml
+++ b/doc/src/sgml/release-12.sgml
@@ -1590,6 +1590,16 @@ Author: Peter Eisentraut <peter_e@gmx.net>
       linkend="catalog-pg-constraint"><structname>pg_constraint</structname></link>.<structfield>consrc</structfield>
       column (Peter Eisentraut)
      </para>
+
+     <para>
+      This column has been deprecated for a long time, because it did not
+      update in response to other catalog changes (such as column renamings).
+      The recommended way to get a text version of a check constraint's
+      expression from <structname>pg_constraint</structname>
+      is <literal>pg_get_expr(conbin, conrelid)</literal>.
+      <function>pg_get_constraintdef()</function> is also a useful
+      alternative.
+     </para>
     </listitem>
 
     <listitem>
@@ -1603,6 +1613,14 @@ Author: Peter Eisentraut <peter_e@gmx.net>
       linkend="catalog-pg-attrdef"><structname>pg_attrdef</structname></link>.<structfield>adsrc</structfield>
       column (Peter Eisentraut)
      </para>
+
+     <para>
+      This column has been deprecated for a long time, because it did not
+      update in response to other catalog changes (such as column renamings).
+      The recommended way to get a text version of a default-value expression
+      from <structname>pg_attrdef</structname> is <literal>pg_get_expr(adbin,
+      adrelid)</literal>.
+     </para>
     </listitem>
 
     <listitem>