Add pg_depend.refobjversion.

Provide a place for the version of referenced database objects to be
recorded.  A follow-up commit will use this to record dependencies on
collation versions for indexes, but similar ideas for other kinds of
objects have also been mooted.

Author: Thomas Munro <thomas.munro@gmail.com>
Reviewed-by: Julien Rouhaud <rjuju123@gmail.com>
Reviewed-by: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Discussion: https://postgr.es/m/CAEepm%3D0uEQCpfq_%2BLYFBdArCe4Ot98t1aR4eYiYTe%3DyavQygiQ%40mail.gmail.com

doc/src/sgml/catalogs.sgml

@@ -3302,6 +3302,17 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
        A code defining the specific semantics of this dependency relationship; see text
       </para></entry>
      </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+       <structfield>refobjversion</structfield> <type>text</type>
+       </para>
+       <para>
+        An optional version for the referenced object.
+       </para>
+      </entry>
+     </row>
+
     </tbody>
    </tgroup>
   </table>

src/backend/catalog/dependency.c

@@ -1600,7 +1600,9 @@ recordDependencyOnExpr(const ObjectAddress *depender,
 
 	/* And record 'em */
 	recordMultipleDependencies(depender,
-							   context.addrs->refs, context.addrs->numrefs,
+							   context.addrs->refs,
+							   context.addrs->numrefs,
+							   NULL,
 							   behavior);
 
 	free_object_addresses(context.addrs);
@@ -1687,7 +1689,9 @@ recordDependencyOnSingleRelExpr(const ObjectAddress *depender,
 		/* Record the self-dependencies with the appropriate direction */
 		if (!reverse_self)
 			recordMultipleDependencies(depender,
-									   self_addrs->refs, self_addrs->numrefs,
+									   self_addrs->refs,
+									   self_addrs->numrefs,
+									   NULL,
 									   self_behavior);
 		else
 		{
@@ -1707,7 +1711,9 @@ recordDependencyOnSingleRelExpr(const ObjectAddress *depender,
 
 	/* Record the external dependencies */
 	recordMultipleDependencies(depender,
-							   context.addrs->refs, context.addrs->numrefs,
+							   context.addrs->refs,
+							   context.addrs->numrefs,
+							   NULL,
 							   behavior);
 
 	free_object_addresses(context.addrs);
@@ -2679,7 +2685,7 @@ record_object_address_dependencies(const ObjectAddress *depender,
 {
 	eliminate_duplicate_dependencies(referenced);
 	recordMultipleDependencies(depender,
-							   referenced->refs, referenced->numrefs,
+							   referenced->refs, referenced->numrefs, NULL,
 							   behavior);
 }
 

src/backend/catalog/pg_depend.c

@@ -24,6 +24,7 @@
 #include "catalog/pg_extension.h"
 #include "commands/extension.h"
 #include "miscadmin.h"
+#include "utils/builtins.h"
 #include "utils/fmgroids.h"
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
@@ -44,7 +45,7 @@ recordDependencyOn(const ObjectAddress *depender,
 				   const ObjectAddress *referenced,
 				   DependencyType behavior)
 {
-	recordMultipleDependencies(depender, referenced, 1, behavior);
+	recordMultipleDependencies(depender, referenced, 1, NULL, behavior);
 }
 
 /*
@@ -55,6 +56,7 @@ void
 recordMultipleDependencies(const ObjectAddress *depender,
 						   const ObjectAddress *referenced,
 						   int nreferenced,
+						   const char *version,
 						   DependencyType behavior)
 {
 	Relation	dependDesc;
@@ -115,6 +117,9 @@ recordMultipleDependencies(const ObjectAddress *depender,
 		 * Record the dependency.  Note we don't bother to check for duplicate
 		 * dependencies; there's no harm in them.
 		 */
+		memset(slot[slot_stored_count]->tts_isnull, false,
+			   slot[slot_stored_count]->tts_tupleDescriptor->natts * sizeof(bool));
+
 		slot[slot_stored_count]->tts_values[Anum_pg_depend_refclassid - 1] = ObjectIdGetDatum(referenced->classId);
 		slot[slot_stored_count]->tts_values[Anum_pg_depend_refobjid - 1] = ObjectIdGetDatum(referenced->objectId);
 		slot[slot_stored_count]->tts_values[Anum_pg_depend_refobjsubid - 1] = Int32GetDatum(referenced->objectSubId);
@@ -122,9 +127,10 @@ recordMultipleDependencies(const ObjectAddress *depender,
 		slot[slot_stored_count]->tts_values[Anum_pg_depend_classid - 1] = ObjectIdGetDatum(depender->classId);
 		slot[slot_stored_count]->tts_values[Anum_pg_depend_objid - 1] = ObjectIdGetDatum(depender->objectId);
 		slot[slot_stored_count]->tts_values[Anum_pg_depend_objsubid - 1] = Int32GetDatum(depender->objectSubId);
-
-		memset(slot[slot_stored_count]->tts_isnull, false,
-			   slot[slot_stored_count]->tts_tupleDescriptor->natts * sizeof(bool));
+		if (version)
+			slot[slot_stored_count]->tts_values[Anum_pg_depend_refobjversion - 1] = CStringGetTextDatum(version);
+		else
+			slot[slot_stored_count]->tts_isnull[Anum_pg_depend_refobjversion - 1] = true;
 
 		ExecStoreVirtualTuple(slot[slot_stored_count]);
 		slot_stored_count++;

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	202011011
+#define CATALOG_VERSION_NO	202011012
 
 #endif

src/include/catalog/dependency.h

@@ -189,6 +189,7 @@ extern void recordDependencyOn(const ObjectAddress *depender,
 extern void recordMultipleDependencies(const ObjectAddress *depender,
 									   const ObjectAddress *referenced,
 									   int nreferenced,
+									   const char *version,
 									   DependencyType behavior);
 
 extern void recordDependencyOnCurrentExtension(const ObjectAddress *object,

src/include/catalog/pg_depend.h

@@ -61,6 +61,10 @@ CATALOG(pg_depend,2608,DependRelationId)
 	 * field.  See DependencyType in catalog/dependency.h.
 	 */
 	char		deptype;		/* see codes in dependency.h */
+#ifdef CATALOG_VARLEN
+	text		refobjversion;	/* version tracking, NULL if not used or
+								 * unknown */
+#endif
 } FormData_pg_depend;
 
 /* ----------------

src/include/catalog/toasting.h

@@ -53,6 +53,7 @@ DECLARE_TOAST(pg_aggregate, 4159, 4160);
 DECLARE_TOAST(pg_attrdef, 2830, 2831);
 DECLARE_TOAST(pg_constraint, 2832, 2833);
 DECLARE_TOAST(pg_default_acl, 4143, 4144);
+DECLARE_TOAST(pg_depend, 8888, 8889);
 DECLARE_TOAST(pg_description, 2834, 2835);
 DECLARE_TOAST(pg_event_trigger, 4145, 4146);
 DECLARE_TOAST(pg_extension, 4147, 4148);

src/test/regress/expected/misc_sanity.out

@@ -18,8 +18,8 @@ WHERE refclassid = 0 OR refobjid = 0 OR
       deptype NOT IN ('a', 'e', 'i', 'n', 'p') OR
       (deptype != 'p' AND (classid = 0 OR objid = 0)) OR
       (deptype = 'p' AND (classid != 0 OR objid != 0 OR objsubid != 0));
- classid | objid | objsubid | refclassid | refobjid | refobjsubid | deptype 
----------+-------+----------+------------+----------+-------------+---------
+ classid | objid | objsubid | refclassid | refobjid | refobjsubid | deptype | refobjversion 
+---------+-------+----------+------------+----------+-------------+---------+---------------
 (0 rows)
 
 -- **************** pg_shdepend ****************