psql: Update \d sequence display

For \d sequencename, the psql code just did SELECT * FROM sequencename
to get the information to display, but this does not contain much
interesting information anymore in PostgreSQL 10, because the metadata
has been moved to a separate system catalog.

This patch creates a newly designed sequence display that is not merely
an extension of the general relation/table display as it was previously.

Example:

PostgreSQL 9.6:

=> \d foobar
           Sequence "public.foobar"
    Column     |  Type   |        Value
---------------+---------+---------------------
 sequence_name | name    | foobar
 last_value    | bigint  | 1
 start_value   | bigint  | 1
 increment_by  | bigint  | 1
 max_value     | bigint  | 9223372036854775807
 min_value     | bigint  | 1
 cache_value   | bigint  | 1
 log_cnt       | bigint  | 0
 is_cycled     | boolean | f
 is_called     | boolean | f

PostgreSQL 10 before this change:

=> \d foobar
   Sequence "public.foobar"
   Column   |  Type   | Value
------------+---------+-------
 last_value | bigint  | 1
 log_cnt    | bigint  | 0
 is_called  | boolean | f

New:

=> \d foobar
                           Sequence "public.foobar"
  Type  | Start | Minimum |       Maximum       | Increment | Cycles? | Cache
--------+-------+---------+---------------------+-----------+---------+-------
 bigint |     1 |       1 | 9223372036854775807 |         1 | no      |     1

Reviewed-by: Fabien COELHO <coelho@cri.ensmp.fr>

src/bin/psql/describe.c

@@ -1380,8 +1380,6 @@ describeOneTableDetails(const char *schemaname,
 	int			i;
 	char	   *view_def = NULL;
 	char	   *headers[11];
-	char	  **seq_values = NULL;
-	char	  **ptr;
 	PQExpBufferData title;
 	PQExpBufferData tmpbuf;
 	int			cols;
@@ -1563,27 +1561,125 @@ describeOneTableDetails(const char *schemaname,
 	res = NULL;
 
 	/*
-	 * If it's a sequence, fetch its values and store into an array that will
+	 * If it's a sequence, deal with it here separately.
-	 * be used later.
 	 */
 	if (tableinfo.relkind == RELKIND_SEQUENCE)
 	{
-		printfPQExpBuffer(&buf, "SELECT * FROM %s", fmtId(schemaname));
+		PGresult   *result = NULL;
+		printQueryOpt myopt = pset.popt;
+		char	   *footers[2] = {NULL, NULL};
+
+		if (pset.sversion >= 100000)
+		{
+			printfPQExpBuffer(&buf,
+							  "SELECT pg_catalog.format_type(seqtypid, NULL) AS \"%s\",\n"
+							  "       seqstart AS \"%s\",\n"
+							  "       seqmin AS \"%s\",\n"
+							  "       seqmax AS \"%s\",\n"
+							  "       seqincrement AS \"%s\",\n"
+							  "       CASE WHEN seqcycle THEN '%s' ELSE '%s' END AS \"%s\",\n"
+							  "       seqcache AS \"%s\"\n",
+							  gettext_noop("Type"),
+							  gettext_noop("Start"),
+							  gettext_noop("Minimum"),
+							  gettext_noop("Maximum"),
+							  gettext_noop("Increment"),
+							  gettext_noop("yes"),
+							  gettext_noop("no"),
+							  gettext_noop("Cycles?"),
+							  gettext_noop("Cache"));
+			appendPQExpBuffer(&buf,
+							  "FROM pg_catalog.pg_sequence\n"
+							  "WHERE seqrelid = '%s';",
+							  oid);
+		}
+		else
+		{
+			printfPQExpBuffer(&buf,
+							  "SELECT pg_catalog.format_type('bigint'::regtype, NULL) AS \"%s\",\n"
+							  "       start_value AS \"%s\",\n"
+							  "       min_value AS \"%s\",\n"
+							  "       max_value AS \"%s\",\n"
+							  "       increment_by AS \"%s\",\n"
+							  "       CASE WHEN is_cycled THEN '%s' ELSE '%s' END AS \"%s\",\n"
+							  "       cache_value AS \"%s\"\n",
+							  gettext_noop("Type"),
+							  gettext_noop("Start"),
+							  gettext_noop("Minimum"),
+							  gettext_noop("Maximum"),
+							  gettext_noop("Increment"),
+							  gettext_noop("yes"),
+							  gettext_noop("no"),
+							  gettext_noop("Cycles?"),
+							  gettext_noop("Cache"));
+			appendPQExpBuffer(&buf, "FROM %s", fmtId(schemaname));
 			/* must be separate because fmtId isn't reentrant */
 			appendPQExpBuffer(&buf, ".%s;", fmtId(relationname));
+		}
 
 		res = PSQLexec(buf.data);
 		if (!res)
 			goto error_return;
 
-		seq_values = pg_malloc((PQnfields(res) + 1) * sizeof(*seq_values));
+		/* Footer information about a sequence */
 
-		for (i = 0; i < PQnfields(res); i++)
+		/* Get the column that owns this sequence */
-			seq_values[i] = pg_strdup(PQgetvalue(res, 0, i));
+		printfPQExpBuffer(&buf, "SELECT pg_catalog.quote_ident(nspname) || '.' ||"
-		seq_values[i] = NULL;
+						  "\n   pg_catalog.quote_ident(relname) || '.' ||"
+						  "\n   pg_catalog.quote_ident(attname),"
+						  "\n   d.deptype"
+						  "\nFROM pg_catalog.pg_class c"
+						  "\nINNER JOIN pg_catalog.pg_depend d ON c.oid=d.refobjid"
+						  "\nINNER JOIN pg_catalog.pg_namespace n ON n.oid=c.relnamespace"
+						  "\nINNER JOIN pg_catalog.pg_attribute a ON ("
+						  "\n a.attrelid=c.oid AND"
+						  "\n a.attnum=d.refobjsubid)"
+						  "\nWHERE d.classid='pg_catalog.pg_class'::pg_catalog.regclass"
+						  "\n AND d.refclassid='pg_catalog.pg_class'::pg_catalog.regclass"
+						  "\n AND d.objid='%s'"
+						  "\n AND d.deptype IN ('a', 'i')",
+						  oid);
 
-		PQclear(res);
+		result = PSQLexec(buf.data);
-		res = NULL;
+
+		/*
+		 * If we get no rows back, don't show anything (obviously). We should
+		 * never get more than one row back, but if we do, just ignore it and
+		 * don't print anything.
+		 */
+		if (!result)
+			goto error_return;
+		else if (PQntuples(result) == 1)
+		{
+			switch (PQgetvalue(result, 0, 1)[0])
+			{
+				case 'a':
+					footers[0] = psprintf(_("Owned by: %s"),
+										  PQgetvalue(result, 0, 0));
+					break;
+				case 'i':
+					footers[0] = psprintf(_("Sequence for identity column: %s"),
+										  PQgetvalue(result, 0, 0));
+					break;
+			}
+		}
+		PQclear(result);
+
+		printfPQExpBuffer(&title, _("Sequence \"%s.%s\""),
+						  schemaname, relationname);
+
+		myopt.footers = footers;
+		myopt.topt.default_footer = false;
+		myopt.title = title.data;
+		myopt.translate_header = true;
+
+		printQuery(res, &myopt, pset.queryFout, false, pset.logfile);
+
+		if (footers[0])
+			free(footers[0]);
+
+		retval = true;
+		goto error_return;		/* not an error, just return early */
 	}
 
 	/*
@@ -1667,10 +1763,6 @@ describeOneTableDetails(const char *schemaname,
 				printfPQExpBuffer(&title, _("Materialized view \"%s.%s\""),
 								  schemaname, relationname);
 			break;
-		case RELKIND_SEQUENCE:
-			printfPQExpBuffer(&title, _("Sequence \"%s.%s\""),
-							  schemaname, relationname);
-			break;
 		case RELKIND_INDEX:
 			if (tableinfo.relpersistence == 'u')
 				printfPQExpBuffer(&title, _("Unlogged index \"%s.%s\""),
@@ -1729,9 +1821,6 @@ describeOneTableDetails(const char *schemaname,
 		show_column_details = true;
 	}
 
-	if (tableinfo.relkind == RELKIND_SEQUENCE)
-		headers[cols++] = gettext_noop("Value");
-
 	if (tableinfo.relkind == RELKIND_INDEX)
 		headers[cols++] = gettext_noop("Definition");
 
@@ -1814,10 +1903,6 @@ describeOneTableDetails(const char *schemaname,
 			printTableAddCell(&cont, default_str, false, false);
 		}
 
-		/* Value: for sequences only */
-		if (tableinfo.relkind == RELKIND_SEQUENCE)
-			printTableAddCell(&cont, seq_values[i], false, false);
-
 		/* Expression for index column */
 		if (tableinfo.relkind == RELKIND_INDEX)
 			printTableAddCell(&cont, PQgetvalue(res, i, 7), false, false);
@@ -2030,55 +2115,6 @@ describeOneTableDetails(const char *schemaname,
 
 		PQclear(result);
 	}
-	else if (tableinfo.relkind == RELKIND_SEQUENCE)
-	{
-		/* Footer information about a sequence */
-		PGresult   *result = NULL;
-
-		/* Get the column that owns this sequence */
-		printfPQExpBuffer(&buf, "SELECT pg_catalog.quote_ident(nspname) || '.' ||"
-						  "\n   pg_catalog.quote_ident(relname) || '.' ||"
-						  "\n   pg_catalog.quote_ident(attname),"
-						  "\n   d.deptype"
-						  "\nFROM pg_catalog.pg_class c"
-						  "\nINNER JOIN pg_catalog.pg_depend d ON c.oid=d.refobjid"
-						  "\nINNER JOIN pg_catalog.pg_namespace n ON n.oid=c.relnamespace"
-						  "\nINNER JOIN pg_catalog.pg_attribute a ON ("
-						  "\n a.attrelid=c.oid AND"
-						  "\n a.attnum=d.refobjsubid)"
-						  "\nWHERE d.classid='pg_catalog.pg_class'::pg_catalog.regclass"
-						  "\n AND d.refclassid='pg_catalog.pg_class'::pg_catalog.regclass"
-						  "\n AND d.objid='%s'"
-						  "\n AND d.deptype IN ('a', 'i')",
-						  oid);
-
-		result = PSQLexec(buf.data);
-		if (!result)
-			goto error_return;
-		else if (PQntuples(result) == 1)
-		{
-			switch (PQgetvalue(result, 0, 1)[0])
-			{
-				case 'a':
-					printfPQExpBuffer(&buf, _("Owned by: %s"),
-									  PQgetvalue(result, 0, 0));
-					printTableAddFooter(&cont, buf.data);
-					break;
-				case 'i':
-					printfPQExpBuffer(&buf, _("Sequence for identity column: %s"),
-									  PQgetvalue(result, 0, 0));
-					printTableAddFooter(&cont, buf.data);
-					break;
-			}
-		}
-
-		/*
-		 * If we get no rows back, don't show anything (obviously). We should
-		 * never get more than one row back, but if we do, just ignore it and
-		 * don't print anything.
-		 */
-		PQclear(result);
-	}
 	else if (tableinfo.relkind == RELKIND_RELATION ||
 			 tableinfo.relkind == RELKIND_MATVIEW ||
 			 tableinfo.relkind == RELKIND_FOREIGN_TABLE ||
@@ -2963,13 +2999,6 @@ error_return:
 	termPQExpBuffer(&title);
 	termPQExpBuffer(&tmpbuf);
 
-	if (seq_values)
-	{
-		for (ptr = seq_values; *ptr; ptr++)
-			free(*ptr);
-		free(seq_values);
-	}
-
 	if (view_def)
 		free(view_def);
 

src/test/regress/expected/identity.out

@@ -32,6 +32,13 @@ SELECT pg_get_serial_sequence('itest1', 'a');
  public.itest1_a_seq
 (1 row)
 
+\d itest1_a_seq
+                    Sequence "public.itest1_a_seq"
+  Type   | Start | Minimum |  Maximum   | Increment | Cycles? | Cache 
+---------+-------+---------+------------+-----------+---------+-------
+ integer |     1 |       1 | 2147483647 |         1 | no      |     1
+Sequence for identity column: public.itest1.a
+
 CREATE TABLE itest4 (a int, b text);
 ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error, requires NOT NULL
 ERROR:  column "a" of relation "itest4" must be declared NOT NULL before identity can be added

src/test/regress/expected/sequence.out

@@ -535,6 +535,19 @@ SELECT * FROM pg_sequence_parameters('sequence_test4'::regclass);
           -1 | -9223372036854775808 |            -1 |        -1 | f            |          1 |        20
 (1 row)
 
+\d sequence_test4
+                       Sequence "public.sequence_test4"
+  Type  | Start |       Minimum        | Maximum | Increment | Cycles? | Cache 
+--------+-------+----------------------+---------+-----------+---------+-------
+ bigint |    -1 | -9223372036854775808 |      -1 |        -1 | no      |     1
+
+\d serialtest2_f2_seq
+                 Sequence "public.serialtest2_f2_seq"
+  Type   | Start | Minimum |  Maximum   | Increment | Cycles? | Cache 
+---------+-------+---------+------------+-----------+---------+-------
+ integer |     1 |       1 | 2147483647 |         1 | no      |     1
+Owned by: public.serialtest2.f2
+
 -- Test comments
 COMMENT ON SEQUENCE asdf IS 'won''t work';
 ERROR:  relation "asdf" does not exist

src/test/regress/sql/identity.sql

@@ -14,6 +14,8 @@ SELECT sequence_name FROM information_schema.sequences WHERE sequence_name LIKE
 
 SELECT pg_get_serial_sequence('itest1', 'a');
 
+\d itest1_a_seq
+
 CREATE TABLE itest4 (a int, b text);
 ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error, requires NOT NULL
 ALTER TABLE itest4 ALTER COLUMN a SET NOT NULL;

src/test/regress/sql/sequence.sql

@@ -246,6 +246,10 @@ WHERE sequencename ~ ANY(ARRAY['sequence_test', 'serialtest'])
 SELECT * FROM pg_sequence_parameters('sequence_test4'::regclass);
 
 
+\d sequence_test4
+\d serialtest2_f2_seq
+
+
 -- Test comments
 COMMENT ON SEQUENCE asdf IS 'won''t work';
 COMMENT ON SEQUENCE sequence_test2 IS 'will work';