Remove obsolete pg_attrdef.adsrc column

This has been deprecated and effectively unused for a long time.
Reviewed-by: Alvaro Herrera <alvherre@2ndquadrant.com>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>

doc/src/sgml/catalogs.sgml

@@ -947,27 +947,13 @@
       <entry><structfield>adbin</structfield></entry>
       <entry><type>pg_node_tree</type></entry>
       <entry></entry>
-      <entry>The internal representation of the column default value</entry>
-     </row>
-
-     <row>
-      <entry><structfield>adsrc</structfield></entry>
-      <entry><type>text</type></entry>
-      <entry></entry>
-      <entry>A human-readable representation of the default value</entry>
+      <entry>The column default value, in <function>nodeToString()</function>
+      representation.  Use <literal>pg_get_expr(adbin, adrelid)</literal> to
+      convert it to an SQL expression.</entry>
      </row>
     </tbody>
    </tgroup>
   </table>
-
-   <para>
-    The <structfield>adsrc</structfield> field is historical, and is best
-    not used, because it does not track outside changes that might affect
-    the representation of the default value.  Reverse-compiling the
-    <structfield>adbin</structfield> field (with <function>pg_get_expr</function> for
-    example) is a better way to display the default value.
-   </para>
-
  </sect1>
 
 

src/backend/catalog/heap.c

@@ -2152,7 +2152,6 @@ StoreAttrDefault(Relation rel, AttrNumber attnum,
 				 Node *expr, bool is_internal, bool add_column_mode)
 {
 	char	   *adbin;
-	char	   *adsrc;
 	Relation	adrel;
 	HeapTuple	tuple;
 	Datum		values[4];
@@ -2169,21 +2168,12 @@ StoreAttrDefault(Relation rel, AttrNumber attnum,
 	 */
 	adbin = nodeToString(expr);
 
-	/*
-	 * Also deparse it to form the mostly-obsolete adsrc field.
-	 */
-	adsrc = deparse_expression(expr,
-							   deparse_context_for(RelationGetRelationName(rel),
-												   RelationGetRelid(rel)),
-							   false, false);
-
 	/*
 	 * Make the pg_attrdef entry.
 	 */
 	values[Anum_pg_attrdef_adrelid - 1] = RelationGetRelid(rel);
 	values[Anum_pg_attrdef_adnum - 1] = attnum;
 	values[Anum_pg_attrdef_adbin - 1] = CStringGetTextDatum(adbin);
-	values[Anum_pg_attrdef_adsrc - 1] = CStringGetTextDatum(adsrc);
 
 	adrel = heap_open(AttrDefaultRelationId, RowExclusiveLock);
 
@@ -2198,10 +2188,8 @@ StoreAttrDefault(Relation rel, AttrNumber attnum,
 
 	/* now can free some of the stuff allocated above */
 	pfree(DatumGetPointer(values[Anum_pg_attrdef_adbin - 1]));
-	pfree(DatumGetPointer(values[Anum_pg_attrdef_adsrc - 1]));
 	heap_freetuple(tuple);
 	pfree(adbin);
-	pfree(adsrc);
 
 	/*
 	 * Update the pg_attribute entry for the column to show that a default

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	201810301
+#define CATALOG_VERSION_NO	201811011
 
 #endif

src/include/catalog/pg_attrdef.h

@@ -33,7 +33,6 @@ CATALOG(pg_attrdef,2604,AttrDefaultRelationId)
 
 #ifdef CATALOG_VARLEN			/* variable-length fields start here */
 	pg_node_tree adbin BKI_FORCE_NOT_NULL;			/* nodeToString representation of default */
-	text		adsrc BKI_FORCE_NOT_NULL;			/* human-readable representation of default */
 #endif
 } FormData_pg_attrdef;