Allow ALTER TYPE to update an existing type's typsubscript value.

tglsfdc · tglsfdc · commit 8c15a297452e · 2020-12-11T18:58:21.000-05:00
This is essential if we'd like to allow existing extension data types to support subscripting in future, since dropping and recreating the type isn't a practical thing for an extension upgrade script, and direct manipulation of pg_type isn't a great answer either. There was some discussion about also allowing alteration of typelem, but it's less clear whether that's a good idea or not, so for now I forebore. Discussion: https://postgr.es/m/3724341.1607551174@sss.pgh.pa.us
diff --git a/doc/src/sgml/ref/alter_type.sgml b/doc/src/sgml/ref/alter_type.sgml
@@ -194,6 +194,14 @@ ALTER TYPE <replaceable class="parameter">name</replaceable> SET ( <replaceable
          requires superuser privilege.
         </para>
        </listitem>
+       <listitem>
+        <para>
+         <literal>SUBSCRIPT</literal> can be set to the name of a type-specific
+         subscripting handler function, or <literal>NONE</literal> to remove
+         the type's subscripting handler function.  Using this option
+         requires superuser privilege.
+        </para>
+       </listitem>
        <listitem>
         <para>
          <literal>STORAGE</literal><indexterm>
diff --git a/src/backend/commands/typecmds.c b/src/backend/commands/typecmds.c
@@ -94,13 +94,15 @@ typedef struct
 	bool		updateTypmodin;
 	bool		updateTypmodout;
 	bool		updateAnalyze;
+	bool		updateSubscript;
 	/* New values for relevant attributes */
 	char		storage;
 	Oid			receiveOid;
 	Oid			sendOid;
 	Oid			typmodinOid;
 	Oid			typmodoutOid;
 	Oid			analyzeOid;
+	Oid			subscriptOid;
 } AlterTypeRecurseParams;
 
 /* Potentially set by pg_upgrade_support functions */
@@ -3885,6 +3887,18 @@ AlterType(AlterTypeStmt *stmt)
 			/* Replacing an analyze function requires superuser. */
 			requireSuper = true;
 		}
+		else if (strcmp(defel->defname, "subscript") == 0)
+		{
+			if (defel->arg != NULL)
+				atparams.subscriptOid =
+					findTypeSubscriptingFunction(defGetQualifiedName(defel),
+												 typeOid);
+			else
+				atparams.subscriptOid = InvalidOid; /* NONE, remove function */
+			atparams.updateSubscript = true;
+			/* Replacing a subscript function requires superuser. */
+			requireSuper = true;
+		}
 
 		/*
 		 * The rest of the options that CREATE accepts cannot be changed.
@@ -4042,6 +4056,11 @@ AlterTypeRecurse(Oid typeOid, bool isImplicitArray,
 		replaces[Anum_pg_type_typanalyze - 1] = true;
 		values[Anum_pg_type_typanalyze - 1] = ObjectIdGetDatum(atparams->analyzeOid);
 	}
+	if (atparams->updateSubscript)
+	{
+		replaces[Anum_pg_type_typsubscript - 1] = true;
+		values[Anum_pg_type_typsubscript - 1] = ObjectIdGetDatum(atparams->subscriptOid);
+	}
 
 	newtup = heap_modify_tuple(tup, RelationGetDescr(catalog),
 							   values, nulls, replaces);
@@ -4098,6 +4117,7 @@ AlterTypeRecurse(Oid typeOid, bool isImplicitArray,
 	atparams->updateReceive = false;	/* domains use F_DOMAIN_RECV */
 	atparams->updateTypmodin = false;	/* domains don't have typmods */
 	atparams->updateTypmodout = false;
+	atparams->updateSubscript = false;	/* domains don't have subscriptors */
 
 	/* Skip the scan if nothing remains to be done */
 	if (!(atparams->updateStorage ||
diff --git a/src/test/regress/expected/create_type.out b/src/test/regress/expected/create_type.out
@@ -260,38 +260,40 @@ ALTER TYPE myvarchar SET (
     receive = myvarcharrecv,
     typmod_in = varchartypmodin,
     typmod_out = varchartypmodout,
-    analyze = array_typanalyze  -- bogus, but it doesn't matter
+    -- these are bogus, but it's safe as long as we don't use the type:
+    analyze = ts_typanalyze,
+    subscript = raw_array_subscript_handler
 );
 SELECT typinput, typoutput, typreceive, typsend, typmodin, typmodout,
-       typanalyze, typstorage
+       typanalyze, typsubscript, typstorage
 FROM pg_type WHERE typname = 'myvarchar';
-  typinput   |  typoutput   |  typreceive   |    typsend    |    typmodin     |    typmodout     |    typanalyze    | typstorage 
--------------+--------------+---------------+---------------+-----------------+------------------+------------------+------------
- myvarcharin | myvarcharout | myvarcharrecv | myvarcharsend | varchartypmodin | varchartypmodout | array_typanalyze | x
+  typinput   |  typoutput   |  typreceive   |    typsend    |    typmodin     |    typmodout     |  typanalyze   |        typsubscript         | typstorage 
+-------------+--------------+---------------+---------------+-----------------+------------------+---------------+-----------------------------+------------
+ myvarcharin | myvarcharout | myvarcharrecv | myvarcharsend | varchartypmodin | varchartypmodout | ts_typanalyze | raw_array_subscript_handler | x
 (1 row)
 
 SELECT typinput, typoutput, typreceive, typsend, typmodin, typmodout,
-       typanalyze, typstorage
+       typanalyze, typsubscript, typstorage
 FROM pg_type WHERE typname = '_myvarchar';
- typinput | typoutput | typreceive |  typsend   |    typmodin     |    typmodout     |    typanalyze    | typstorage 
-----------+-----------+------------+------------+-----------------+------------------+------------------+------------
- array_in | array_out | array_recv | array_send | varchartypmodin | varchartypmodout | array_typanalyze | x
+ typinput | typoutput | typreceive |  typsend   |    typmodin     |    typmodout     |    typanalyze    |      typsubscript       | typstorage 
+----------+-----------+------------+------------+-----------------+------------------+------------------+-------------------------+------------
+ array_in | array_out | array_recv | array_send | varchartypmodin | varchartypmodout | array_typanalyze | array_subscript_handler | x
 (1 row)
 
 SELECT typinput, typoutput, typreceive, typsend, typmodin, typmodout,
-       typanalyze, typstorage
+       typanalyze, typsubscript, typstorage
 FROM pg_type WHERE typname = 'myvarchardom';
- typinput  |  typoutput   | typreceive  |    typsend    | typmodin | typmodout |    typanalyze    | typstorage 
------------+--------------+-------------+---------------+----------+-----------+------------------+------------
- domain_in | myvarcharout | domain_recv | myvarcharsend | -        | -         | array_typanalyze | x
+ typinput  |  typoutput   | typreceive  |    typsend    | typmodin | typmodout |  typanalyze   | typsubscript | typstorage 
+-----------+--------------+-------------+---------------+----------+-----------+---------------+--------------+------------
+ domain_in | myvarcharout | domain_recv | myvarcharsend | -        | -         | ts_typanalyze | -            | x
 (1 row)
 
 SELECT typinput, typoutput, typreceive, typsend, typmodin, typmodout,
-       typanalyze, typstorage
+       typanalyze, typsubscript, typstorage
 FROM pg_type WHERE typname = '_myvarchardom';
- typinput | typoutput | typreceive |  typsend   | typmodin | typmodout |    typanalyze    | typstorage 
-----------+-----------+------------+------------+----------+-----------+------------------+------------
- array_in | array_out | array_recv | array_send | -        | -         | array_typanalyze | x
+ typinput | typoutput | typreceive |  typsend   | typmodin | typmodout |    typanalyze    |      typsubscript       | typstorage 
+----------+-----------+------------+------------+----------+-----------+------------------+-------------------------+------------
+ array_in | array_out | array_recv | array_send | -        | -         | array_typanalyze | array_subscript_handler | x
 (1 row)
 
 -- ensure dependencies are straight
diff --git a/src/test/regress/sql/create_type.sql b/src/test/regress/sql/create_type.sql
@@ -207,23 +207,25 @@ ALTER TYPE myvarchar SET (
     receive = myvarcharrecv,
     typmod_in = varchartypmodin,
     typmod_out = varchartypmodout,
-    analyze = array_typanalyze  -- bogus, but it doesn't matter
+    -- these are bogus, but it's safe as long as we don't use the type:
+    analyze = ts_typanalyze,
+    subscript = raw_array_subscript_handler
 );
 
 SELECT typinput, typoutput, typreceive, typsend, typmodin, typmodout,
-       typanalyze, typstorage
+       typanalyze, typsubscript, typstorage
 FROM pg_type WHERE typname = 'myvarchar';
 
 SELECT typinput, typoutput, typreceive, typsend, typmodin, typmodout,
-       typanalyze, typstorage
+       typanalyze, typsubscript, typstorage
 FROM pg_type WHERE typname = '_myvarchar';
 
 SELECT typinput, typoutput, typreceive, typsend, typmodin, typmodout,
-       typanalyze, typstorage
+       typanalyze, typsubscript, typstorage
 FROM pg_type WHERE typname = 'myvarchardom';
 
 SELECT typinput, typoutput, typreceive, typsend, typmodin, typmodout,
-       typanalyze, typstorage
+       typanalyze, typsubscript, typstorage
 FROM pg_type WHERE typname = '_myvarchardom';
 
 -- ensure dependencies are straight
