Allow psql's \dt and \di to show TOAST tables and their indexes.

Formerly, TOAST objects were unconditionally suppressed, but since
\d is able to print them it's not very clear why these variants
should not.  Instead, use the same rules as for system catalogs:
they can be seen if you write the 'S' modifier or a table name
pattern.  (In practice, since hardly anybody would keep pg_toast
in their search_path, it's really down to whether you use a pattern
that can match pg_toast.*.)

No docs change seems necessary because the docs already say that
this happens for "system objects"; we're just classifying TOAST
tables as being that.

Justin Pryzby, reviewed by Laurenz Albe

Discussion: https://postgr.es/m/20201130165436.GX24052@telsasoft.com

src/bin/psql/describe.c

@@ -3718,6 +3718,7 @@ listTables(const char *tabtypes, const char *pattern, bool verbose, bool showSys
 					  " WHEN " CppAsString2(RELKIND_INDEX) " THEN '%s'"
 					  " WHEN " CppAsString2(RELKIND_SEQUENCE) " THEN '%s'"
 					  " WHEN 's' THEN '%s'"
+					  " WHEN " CppAsString2(RELKIND_TOASTVALUE) " THEN '%s'"
 					  " WHEN " CppAsString2(RELKIND_FOREIGN_TABLE) " THEN '%s'"
 					  " WHEN " CppAsString2(RELKIND_PARTITIONED_TABLE) " THEN '%s'"
 					  " WHEN " CppAsString2(RELKIND_PARTITIONED_INDEX) " THEN '%s'"
@@ -3731,6 +3732,7 @@ listTables(const char *tabtypes, const char *pattern, bool verbose, bool showSys
 					  gettext_noop("index"),
 					  gettext_noop("sequence"),
 					  gettext_noop("special"),
+					  gettext_noop("TOAST table"),
 					  gettext_noop("foreign table"),
 					  gettext_noop("partitioned table"),
 					  gettext_noop("partitioned index"),
@@ -3813,8 +3815,13 @@ listTables(const char *tabtypes, const char *pattern, bool verbose, bool showSys
 
 	appendPQExpBufferStr(&buf, "\nWHERE c.relkind IN (");
 	if (showTables)
+	{
 		appendPQExpBufferStr(&buf, CppAsString2(RELKIND_RELATION) ","
 							 CppAsString2(RELKIND_PARTITIONED_TABLE) ",");
+		/* with 'S' or a pattern, allow 't' to match TOAST tables too */
+		if (showSystem || pattern)
+			appendPQExpBufferStr(&buf, CppAsString2(RELKIND_TOASTVALUE) ",");
+	}
 	if (showViews)
 		appendPQExpBufferStr(&buf, CppAsString2(RELKIND_VIEW) ",");
 	if (showMatViews)
@@ -3834,17 +3841,9 @@ listTables(const char *tabtypes, const char *pattern, bool verbose, bool showSys
 
 	if (!showSystem && !pattern)
 		appendPQExpBufferStr(&buf, "      AND n.nspname <> 'pg_catalog'\n"
+							 "      AND n.nspname !~ '^pg_toast'\n"
 							 "      AND n.nspname <> 'information_schema'\n");
 
-	/*
-	 * TOAST objects are suppressed unconditionally.  Since we don't provide
-	 * any way to select RELKIND_TOASTVALUE above, we would never show toast
-	 * tables in any case; it seems a bit confusing to allow their indexes to
-	 * be shown.  Use plain \d if you really need to look at a TOAST
-	 * table/index.
-	 */
-	appendPQExpBufferStr(&buf, "      AND n.nspname !~ '^pg_toast'\n");
-
 	processSQLNamePattern(pset.db, &buf, pattern, true, false,
 						  "n.nspname", "c.relname", NULL,
 						  "pg_catalog.pg_table_is_visible(c.oid)");
@@ -4057,17 +4056,9 @@ listPartitionedTables(const char *reltypes, const char *pattern, bool verbose)
 
 	if (!pattern)
 		appendPQExpBufferStr(&buf, "      AND n.nspname <> 'pg_catalog'\n"
+							 "      AND n.nspname !~ '^pg_toast'\n"
 							 "      AND n.nspname <> 'information_schema'\n");
 
-	/*
-	 * TOAST objects are suppressed unconditionally.  Since we don't provide
-	 * any way to select RELKIND_TOASTVALUE above, we would never show toast
-	 * tables in any case; it seems a bit confusing to allow their indexes to
-	 * be shown.  Use plain \d if you really need to look at a TOAST
-	 * table/index.
-	 */
-	appendPQExpBufferStr(&buf, "      AND n.nspname !~ '^pg_toast'\n");
-
 	processSQLNamePattern(pset.db, &buf, pattern, true, false,
 						  "n.nspname", "c.relname", NULL,
 						  "pg_catalog.pg_table_is_visible(c.oid)");

src/test/regress/expected/psql.out

@@ -4895,6 +4895,20 @@ Owning table: "pg_catalog.pg_statistic"
 Indexes:
     "pg_toast_2619_index" PRIMARY KEY, btree (chunk_id, chunk_seq)
 
+\dt pg_toast.pg_toast_2619
+                 List of relations
+  Schema  |     Name      |    Type     |  Owner   
+----------+---------------+-------------+----------
+ pg_toast | pg_toast_2619 | TOAST table | postgres
+(1 row)
+
+\di pg_toast.pg_toast_2619_index
+                         List of relations
+  Schema  |        Name         | Type  |  Owner   |     Table     
+----------+---------------------+-------+----------+---------------
+ pg_toast | pg_toast_2619_index | index | postgres | pg_toast_2619
+(1 row)
+
 -- check printing info about access methods
 \dA
 List of access methods

src/test/regress/sql/psql.sql

@@ -1210,6 +1210,8 @@ drop role regress_partitioning_role;
 
 -- \d on toast table (use pg_statistic's toast table, which has a known name)
 \d pg_toast.pg_toast_2619
+\dt pg_toast.pg_toast_2619
+\di pg_toast.pg_toast_2619_index
 
 -- check printing info about access methods
 \dA