Unlogged sequences

Add support for unlogged sequences.  Unlike for unlogged tables, this
is not a performance feature.  It allows sequences associated with
unlogged tables to be excluded from replication.

A new subcommand ALTER SEQUENCE ... SET LOGGED/UNLOGGED is added.

An identity/serial sequence now automatically gets and follows the
persistence level (logged/unlogged) of its owning table.  (The
sequences owned by temporary tables were already temporary through the
separate mechanism in RangeVarAdjustRelationPersistence().)  But you
can still change the persistence of an owned sequence separately.
Also, pg_dump and pg_upgrade preserve the persistence of existing
sequences.

Discussion: https://www.postgresql.org/message-id/flat/04e12818-2f98-257c-b926-2845d74ed04f%402ndquadrant.com

11 files changed, 188 insertions, 27 deletions

diff --git a/src/backend/commands/sequence.c b/src/backend/commands/sequence.c
index 717bb0b2aa9..47f62c28d42 100644
--- a/src/backend/commands/sequence.c
+++ b/src/backend/commands/sequence.c
@@ -30,6 +30,7 @@
 #include "catalog/objectaccess.h"
 #include "catalog/pg_sequence.h"
 #include "catalog/pg_type.h"
+#include "catalog/storage_xlog.h"
 #include "commands/defrem.h"
 #include "commands/sequence.h"
 #include "commands/tablecmds.h"
@@ -95,6 +96,7 @@ static HTAB *seqhashtab = NULL; /* hash table for SeqTable items */
 static SeqTableData *last_used_seq = NULL;
 
 static void fill_seq_with_data(Relation rel, HeapTuple tuple);
+static void fill_seq_fork_with_data(Relation rel, HeapTuple tuple, ForkNumber forkNum);
 static Relation lock_and_open_sequence(SeqTable seq);
 static void create_seq_hashtable(void);
 static void init_sequence(Oid relid, SeqTable *p_elm, Relation *p_rel);
@@ -133,12 +135,6 @@ DefineSequence(ParseState *pstate, CreateSeqStmt *seq)
 	bool		pgs_nulls[Natts_pg_sequence];
 	int			i;
 
-	/* Unlogged sequences are not implemented -- not clear if useful. */
-	if (seq->sequence->relpersistence == RELPERSISTENCE_UNLOGGED)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("unlogged sequences are not supported")));
-
 	/*
 	 * If if_not_exists was given and a relation with the same name already
 	 * exists, bail out. (Note: we needn't check this when not if_not_exists,
@@ -492,10 +488,34 @@ SetSequence(Oid seq_relid, bool transactional, int64 last_value, int64 log_cnt,
 
 /*
  * Initialize a sequence's relation with the specified tuple as content
+ *
+ * This handles unlogged sequences by writing to both the main and the init
+ * fork as necessary.
  */
 static void
 fill_seq_with_data(Relation rel, HeapTuple tuple)
 {
+	fill_seq_fork_with_data(rel, tuple, MAIN_FORKNUM);
+
+	if (rel->rd_rel->relpersistence == RELPERSISTENCE_UNLOGGED)
+	{
+		SMgrRelation srel;
+
+		srel = smgropen(rel->rd_node, InvalidBackendId);
+		smgrcreate(srel, INIT_FORKNUM, false);
+		log_smgrcreate(&rel->rd_node, INIT_FORKNUM);
+		fill_seq_fork_with_data(rel, tuple, INIT_FORKNUM);
+		FlushRelationBuffers(rel);
+		smgrclose(srel);
+	}
+}
+
+/*
+ * Initialize a sequence's relation fork with the specified tuple as content
+ */
+static void
+fill_seq_fork_with_data(Relation rel, HeapTuple tuple, ForkNumber forkNum)
+{
 	Buffer		buf;
 	Page		page;
 	sequence_magic *sm;
@@ -503,7 +523,7 @@ fill_seq_with_data(Relation rel, HeapTuple tuple)
 
 	/* Initialize first page of relation with special magic number */
 
-	buf = ReadBuffer(rel, P_NEW);
+	buf = ReadBufferExtended(rel, forkNum, P_NEW, RBM_NORMAL, NULL);
 	Assert(BufferGetBlockNumber(buf) == 0);
 
 	page = BufferGetPage(buf);
@@ -549,7 +569,7 @@ fill_seq_with_data(Relation rel, HeapTuple tuple)
 		elog(ERROR, "failed to add sequence tuple to page");
 
 	/* XLOG stuff */
-	if (RelationNeedsWAL(rel))
+	if (RelationNeedsWAL(rel) || forkNum == INIT_FORKNUM)
 	{
 		xl_seq_rec	xlrec;
 		XLogRecPtr	recptr;
@@ -683,6 +703,28 @@ AlterSequence(ParseState *pstate, AlterSeqStmt *stmt)
 }
 
 void
+SequenceChangePersistence(Oid relid, char newrelpersistence)
+{
+	SeqTable	elm;
+	Relation	seqrel;
+	Buffer		buf;
+	HeapTupleData seqdatatuple;
+
+	init_sequence(relid, &elm, &seqrel);
+
+	/* check the comment above nextval_internal()'s equivalent call. */
+	if (RelationNeedsWAL(seqrel))
+		GetTopTransactionId();
+
+	(void) read_seq_tuple(seqrel, &buf, &seqdatatuple);
+	RelationSetNewRelfilenode(seqrel, newrelpersistence);
+	fill_seq_with_data(seqrel, &seqdatatuple);
+	UnlockReleaseBuffer(buf);
+
+	relation_close(seqrel, NoLock);
+}
+
+void
 DeleteSequenceTuple(Oid relid)
 {
 	Relation	rel;
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index a241b444975..4dd545cdd20 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -319,6 +319,7 @@ struct DropRelationCallbackState
 #define		ATT_COMPOSITE_TYPE		0x0010
 #define		ATT_FOREIGN_TABLE		0x0020
 #define		ATT_PARTITIONED_INDEX	0x0040
+#define		ATT_SEQUENCE			0x0080
 
 /*
  * ForeignTruncateInfo
@@ -4660,7 +4661,7 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			pass = AT_PASS_MISC;
 			break;
 		case AT_SetLogged:		/* SET LOGGED */
-			ATSimplePermissions(cmd->subtype, rel, ATT_TABLE);
+			ATSimplePermissions(cmd->subtype, rel, ATT_TABLE | ATT_SEQUENCE);
 			if (tab->chgPersistence)
 				ereport(ERROR,
 						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
@@ -4675,7 +4676,7 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			pass = AT_PASS_MISC;
 			break;
 		case AT_SetUnLogged:	/* SET UNLOGGED */
-			ATSimplePermissions(cmd->subtype, rel, ATT_TABLE);
+			ATSimplePermissions(cmd->subtype, rel, ATT_TABLE | ATT_SEQUENCE);
 			if (tab->chgPersistence)
 				ereport(ERROR,
 						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
@@ -5425,7 +5426,7 @@ ATRewriteTables(AlterTableStmt *parsetree, List **wqueue, LOCKMODE lockmode,
 		 * and assigns a new relfilenode, we automatically create or drop an
 		 * init fork for the relation as appropriate.
 		 */
-		if (tab->rewrite > 0)
+		if (tab->rewrite > 0 && tab->relkind != RELKIND_SEQUENCE)
 		{
 			/* Build a temporary relation and copy data */
 			Relation	OldHeap;
@@ -5546,6 +5547,11 @@ ATRewriteTables(AlterTableStmt *parsetree, List **wqueue, LOCKMODE lockmode,
 
 			InvokeObjectPostAlterHook(RelationRelationId, tab->relid, 0);
 		}
+		else if (tab->rewrite > 0 && tab->relkind == RELKIND_SEQUENCE)
+		{
+			if (tab->chgPersistence)
+				SequenceChangePersistence(tab->relid, tab->newrelpersistence);
+		}
 		else
 		{
 			/*
@@ -5564,6 +5570,23 @@ ATRewriteTables(AlterTableStmt *parsetree, List **wqueue, LOCKMODE lockmode,
 			if (tab->newTableSpace)
 				ATExecSetTableSpace(tab->relid, tab->newTableSpace, lockmode);
 		}
+
+		/*
+		 * Also change persistence of owned sequences, so that it matches the
+		 * table persistence.
+		 */
+		if (tab->chgPersistence)
+		{
+			List	   *seqlist = getOwnedSequences(tab->relid);
+			ListCell   *lc;
+
+			foreach(lc, seqlist)
+			{
+				Oid         seq_relid = lfirst_oid(lc);
+
+				SequenceChangePersistence(seq_relid, tab->newrelpersistence);
+			}
+		}
 	}
 
 	/*
@@ -6224,6 +6247,9 @@ ATSimplePermissions(AlterTableType cmdtype, Relation rel, int allowed_targets)
 		case RELKIND_FOREIGN_TABLE:
 			actual_target = ATT_FOREIGN_TABLE;
 			break;
+		case RELKIND_SEQUENCE:
+			actual_target = ATT_SEQUENCE;
+			break;
 		default:
 			actual_target = 0;
 			break;
diff --git a/src/backend/parser/parse_utilcmd.c b/src/backend/parser/parse_utilcmd.c
index cd946c76921..2826559d09b 100644
--- a/src/backend/parser/parse_utilcmd.c
+++ b/src/backend/parser/parse_utilcmd.c
@@ -445,6 +445,7 @@ generateSerialExtraStmts(CreateStmtContext *cxt, ColumnDef *column,
 	seqstmt = makeNode(CreateSeqStmt);
 	seqstmt->for_identity = for_identity;
 	seqstmt->sequence = makeRangeVar(snamespace, sname, -1);
+	seqstmt->sequence->relpersistence = cxt->relation->relpersistence;
 	seqstmt->options = seqoptions;
 
 	/*
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 535b1601655..3c2201a725f 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -16570,6 +16570,7 @@ dumpSequence(Archive *fout, const TableInfo *tbinfo)
 	PQExpBuffer query = createPQExpBuffer();
 	PQExpBuffer delqry = createPQExpBuffer();
 	char	   *qseqname;
+	TableInfo  *owning_tab = NULL;
 
 	qseqname = pg_strdup(fmtId(tbinfo->dobj.name));
 
@@ -16678,7 +16679,7 @@ dumpSequence(Archive *fout, const TableInfo *tbinfo)
 
 	if (tbinfo->is_identity_sequence)
 	{
-		TableInfo  *owning_tab = findTableByOid(tbinfo->owning_tab);
+		owning_tab = findTableByOid(tbinfo->owning_tab);
 
 		appendPQExpBuffer(query,
 						  "ALTER TABLE %s ",
@@ -16696,7 +16697,9 @@ dumpSequence(Archive *fout, const TableInfo *tbinfo)
 	else
 	{
 		appendPQExpBuffer(query,
-						  "CREATE SEQUENCE %s\n",
+						  "CREATE %sSEQUENCE %s\n",
+						  tbinfo->relpersistence == RELPERSISTENCE_UNLOGGED ?
+						  "UNLOGGED " : "",
 						  fmtQualifiedDumpable(tbinfo));
 
 		if (strcmp(seqtype, "bigint") != 0)
@@ -16722,7 +16725,15 @@ dumpSequence(Archive *fout, const TableInfo *tbinfo)
 					  cache, (cycled ? "\n    CYCLE" : ""));
 
 	if (tbinfo->is_identity_sequence)
+	{
 		appendPQExpBufferStr(query, "\n);\n");
+		if (tbinfo->relpersistence != owning_tab->relpersistence)
+			appendPQExpBuffer(query,
+							  "ALTER SEQUENCE %s SET %s;\n",
+							  fmtQualifiedDumpable(tbinfo),
+							  tbinfo->relpersistence == RELPERSISTENCE_UNLOGGED ?
+							  "UNLOGGED" : "LOGGED");
+	}
 	else
 		appendPQExpBufferStr(query, ";\n");
 
diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index 4dddf087893..73bbbe2eb40 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -1681,8 +1681,12 @@ describeOneTableDetails(const char *schemaname,
 		printTableInit(&cont, &myopt, title.data, 7, numrows);
 		printTableInitialized = true;
 
-		printfPQExpBuffer(&title, _("Sequence \"%s.%s\""),
-						  schemaname, relationname);
+		if (tableinfo.relpersistence == 'u')
+			printfPQExpBuffer(&title, _("Unlogged sequence \"%s.%s\""),
+							  schemaname, relationname);
+		else
+			printfPQExpBuffer(&title, _("Sequence \"%s.%s\""),
+							  schemaname, relationname);
 
 		printTableAddHeader(&cont, gettext_noop("Type"), true, 'l');
 		printTableAddHeader(&cont, gettext_noop("Start"), true, 'r');
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 32d0b4855f5..025d3f71a11 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2116,7 +2116,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER SEQUENCE <name> */
 	else if (Matches("ALTER", "SEQUENCE", MatchAny))
 		COMPLETE_WITH("AS", "INCREMENT", "MINVALUE", "MAXVALUE", "RESTART",
-					  "NO", "CACHE", "CYCLE", "SET SCHEMA", "OWNED BY",
+					  "NO", "CACHE", "CYCLE", "SET", "OWNED BY",
 					  "OWNER TO", "RENAME TO");
 	/* ALTER SEQUENCE <name> AS */
 	else if (TailMatches("ALTER", "SEQUENCE", MatchAny, "AS"))
@@ -2124,6 +2124,9 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER SEQUENCE <name> NO */
 	else if (Matches("ALTER", "SEQUENCE", MatchAny, "NO"))
 		COMPLETE_WITH("MINVALUE", "MAXVALUE", "CYCLE");
+	/* ALTER SEQUENCE <name> SET */
+	else if (Matches("ALTER", "SEQUENCE", MatchAny, "SET"))
+		COMPLETE_WITH("SCHEMA", "LOGGED", "UNLOGGED");
 	/* ALTER SERVER <name> */
 	else if (Matches("ALTER", "SERVER", MatchAny))
 		COMPLETE_WITH("VERSION", "OPTIONS", "OWNER TO", "RENAME TO");
diff --git a/src/include/commands/sequence.h b/src/include/commands/sequence.h
index 5bab90db8e0..f2381982d5d 100644
--- a/src/include/commands/sequence.h
+++ b/src/include/commands/sequence.h
@@ -58,6 +58,7 @@ extern List *sequence_options(Oid relid);
 
 extern ObjectAddress DefineSequence(ParseState *pstate, CreateSeqStmt *stmt);
 extern ObjectAddress AlterSequence(ParseState *pstate, AlterSeqStmt *stmt);
+extern void SequenceChangePersistence(Oid relid, char newrelpersistence);
 extern void DeleteSequenceTuple(Oid relid);
 extern void ResetSequence(Oid seq_relid);
 extern void SetSequence(Oid seq_relid, bool transactional, int64 last_value, int64 log_cnt, bool is_called);
diff --git a/src/test/recovery/t/014_unlogged_reinit.pl b/src/test/recovery/t/014_unlogged_reinit.pl
index f3199fbd2e1..0dca3f69fe3 100644
--- a/src/test/recovery/t/014_unlogged_reinit.pl
+++ b/src/test/recovery/t/014_unlogged_reinit.pl
@@ -18,16 +18,27 @@ $node->init;
 $node->start;
 my $pgdata = $node->data_dir;
 
-# Create an unlogged table to test that forks other than init are not
-# copied.
+# Create an unlogged table and an unlogged sequence to test that forks
+# other than init are not copied.
 $node->safe_psql('postgres', 'CREATE UNLOGGED TABLE base_unlogged (id int)');
+$node->safe_psql('postgres', 'CREATE UNLOGGED SEQUENCE seq_unlogged');
 
 my $baseUnloggedPath = $node->safe_psql('postgres',
 	q{select pg_relation_filepath('base_unlogged')});
+my $seqUnloggedPath = $node->safe_psql('postgres',
+	q{select pg_relation_filepath('seq_unlogged')});
 
 # Test that main and init forks exist.
-ok(-f "$pgdata/${baseUnloggedPath}_init", 'init fork in base exists');
-ok(-f "$pgdata/$baseUnloggedPath",        'main fork in base exists');
+ok(-f "$pgdata/${baseUnloggedPath}_init", 'table init fork exists');
+ok(-f "$pgdata/$baseUnloggedPath",        'table main fork exists');
+ok(-f "$pgdata/${seqUnloggedPath}_init",  'sequence init fork exists');
+ok(-f "$pgdata/$seqUnloggedPath",         'sequence main fork exists');
+
+# Test the sequence
+is($node->safe_psql('postgres', "SELECT nextval('seq_unlogged')"),
+	1, 'sequence nextval');
+is($node->safe_psql('postgres', "SELECT nextval('seq_unlogged')"),
+	2, 'sequence nextval again');
 
 # Create an unlogged table in a tablespace.
 
@@ -44,6 +55,19 @@ my $ts1UnloggedPath = $node->safe_psql('postgres',
 ok(-f "$pgdata/${ts1UnloggedPath}_init", 'init fork in tablespace exists');
 ok(-f "$pgdata/$ts1UnloggedPath",        'main fork in tablespace exists');
 
+# Create more unlogged sequences for testing.
+$node->safe_psql('postgres', 'CREATE UNLOGGED SEQUENCE seq_unlogged2');
+# This rewrites the sequence relation in AlterSequence().
+$node->safe_psql('postgres', 'ALTER SEQUENCE seq_unlogged2 INCREMENT 2');
+$node->safe_psql('postgres', "SELECT nextval('seq_unlogged2')");
+
+$node->safe_psql('postgres',
+	'CREATE UNLOGGED TABLE tab_seq_unlogged3 (a int GENERATED ALWAYS AS IDENTITY)'
+);
+# This rewrites the sequence relation in ResetSequence().
+$node->safe_psql('postgres', 'TRUNCATE tab_seq_unlogged3 RESTART IDENTITY');
+$node->safe_psql('postgres', 'INSERT INTO tab_seq_unlogged3 DEFAULT VALUES');
+
 # Crash the postmaster.
 $node->stop('immediate');
 
@@ -54,6 +78,8 @@ append_to_file("$pgdata/${baseUnloggedPath}_fsm", 'TEST_FSM');
 # Remove main fork to test that it is recopied from init.
 unlink("$pgdata/${baseUnloggedPath}")
   or BAIL_OUT("could not remove \"${baseUnloggedPath}\": $!");
+unlink("$pgdata/${seqUnloggedPath}")
+  or BAIL_OUT("could not remove \"${seqUnloggedPath}\": $!");
 
 # the same for the tablespace
 append_to_file("$pgdata/${ts1UnloggedPath}_vm",  'TEST_VM');
@@ -64,13 +90,25 @@ unlink("$pgdata/${ts1UnloggedPath}")
 $node->start;
 
 # check unlogged table in base
-ok(-f "$pgdata/${baseUnloggedPath}_init", 'init fork in base still exists');
-ok(-f "$pgdata/$baseUnloggedPath", 'main fork in base recreated at startup');
+ok( -f "$pgdata/${baseUnloggedPath}_init",
+	'table init fork in base still exists');
+ok(-f "$pgdata/$baseUnloggedPath",
+	'table main fork in base recreated at startup');
 ok(!-f "$pgdata/${baseUnloggedPath}_vm",
 	'vm fork in base removed at startup');
 ok( !-f "$pgdata/${baseUnloggedPath}_fsm",
 	'fsm fork in base removed at startup');
 
+# check unlogged sequence
+ok(-f "$pgdata/${seqUnloggedPath}_init", 'sequence init fork still exists');
+ok(-f "$pgdata/$seqUnloggedPath", 'sequence main fork recreated at startup');
+
+# Test the sequence after restart
+is($node->safe_psql('postgres', "SELECT nextval('seq_unlogged')"),
+	1, 'sequence nextval after restart');
+is($node->safe_psql('postgres', "SELECT nextval('seq_unlogged')"),
+	2, 'sequence nextval after restart again');
+
 # check unlogged table in tablespace
 ok( -f "$pgdata/${ts1UnloggedPath}_init",
 	'init fork still exists in tablespace');
@@ -81,4 +119,15 @@ ok( !-f "$pgdata/${ts1UnloggedPath}_vm",
 ok( !-f "$pgdata/${ts1UnloggedPath}_fsm",
 	'fsm fork in tablespace removed at startup');
 
+# Test other sequences
+is($node->safe_psql('postgres', "SELECT nextval('seq_unlogged2')"),
+	1, 'altered sequence nextval after restart');
+is($node->safe_psql('postgres', "SELECT nextval('seq_unlogged2')"),
+	3, 'altered sequence nextval after restart again');
+
+$node->safe_psql('postgres',
+	"INSERT INTO tab_seq_unlogged3 VALUES (DEFAULT), (DEFAULT)");
+is($node->safe_psql('postgres', "SELECT * FROM tab_seq_unlogged3"),
+	"1\n2", 'reset sequence nextval after restart');
+
 done_testing();
diff --git a/src/test/regress/expected/alter_table.out b/src/test/regress/expected/alter_table.out
index 07473dd6600..5ede56d9b55 100644
--- a/src/test/regress/expected/alter_table.out
+++ b/src/test/regress/expected/alter_table.out
@@ -3461,7 +3461,7 @@ ORDER BY relname;
  unlogged1             | r       | u
  unlogged1 toast index | i       | u
  unlogged1 toast table | t       | u
- unlogged1_f1_seq      | S       | p
+ unlogged1_f1_seq      | S       | u
  unlogged1_pkey        | i       | u
 (5 rows)
 
@@ -3528,7 +3528,7 @@ ORDER BY relname;
  logged1             | r       | u
  logged1 toast index | i       | u
  logged1 toast table | t       | u
- logged1_f1_seq      | S       | p
+ logged1_f1_seq      | S       | u
  logged1_pkey        | i       | u
 (5 rows)
 
diff --git a/src/test/regress/expected/sequence.out b/src/test/regress/expected/sequence.out
index 71c2b0f1dff..7cb2f7cc02b 100644
--- a/src/test/regress/expected/sequence.out
+++ b/src/test/regress/expected/sequence.out
@@ -2,8 +2,6 @@
 -- CREATE SEQUENCE
 --
 -- various error cases
-CREATE UNLOGGED SEQUENCE sequence_testx;
-ERROR:  unlogged sequences are not supported
 CREATE SEQUENCE sequence_testx INCREMENT BY 0;
 ERROR:  INCREMENT must not be zero
 CREATE SEQUENCE sequence_testx INCREMENT BY -1 MINVALUE 20;
@@ -600,6 +598,24 @@ DROP SEQUENCE seq2;
 -- should fail
 SELECT lastval();
 ERROR:  lastval is not yet defined in this session
+-- unlogged sequences
+-- (more tests in src/test/recovery/)
+CREATE UNLOGGED SEQUENCE sequence_test_unlogged;
+ALTER SEQUENCE sequence_test_unlogged SET LOGGED;
+\d sequence_test_unlogged
+                   Sequence "public.sequence_test_unlogged"
+  Type  | Start | Minimum |       Maximum       | Increment | Cycles? | Cache 
+--------+-------+---------+---------------------+-----------+---------+-------
+ bigint |     1 |       1 | 9223372036854775807 |         1 | no      |     1
+
+ALTER SEQUENCE sequence_test_unlogged SET UNLOGGED;
+\d sequence_test_unlogged
+              Unlogged sequence "public.sequence_test_unlogged"
+  Type  | Start | Minimum |       Maximum       | Increment | Cycles? | Cache 
+--------+-------+---------+---------------------+-----------+---------+-------
+ bigint |     1 |       1 | 9223372036854775807 |         1 | no      |     1
+
+DROP SEQUENCE sequence_test_unlogged;
 -- Test sequences in read-only transactions
 CREATE TEMPORARY SEQUENCE sequence_test_temp1;
 START TRANSACTION READ ONLY;
diff --git a/src/test/regress/sql/sequence.sql b/src/test/regress/sql/sequence.sql
index 7928ee23ee8..674f5f1f668 100644
--- a/src/test/regress/sql/sequence.sql
+++ b/src/test/regress/sql/sequence.sql
@@ -3,7 +3,6 @@
 --
 
 -- various error cases
-CREATE UNLOGGED SEQUENCE sequence_testx;
 CREATE SEQUENCE sequence_testx INCREMENT BY 0;
 CREATE SEQUENCE sequence_testx INCREMENT BY -1 MINVALUE 20;
 CREATE SEQUENCE sequence_testx INCREMENT BY 1 MAXVALUE -20;
@@ -272,6 +271,15 @@ DROP SEQUENCE seq2;
 -- should fail
 SELECT lastval();
 
+-- unlogged sequences
+-- (more tests in src/test/recovery/)
+CREATE UNLOGGED SEQUENCE sequence_test_unlogged;
+ALTER SEQUENCE sequence_test_unlogged SET LOGGED;
+\d sequence_test_unlogged
+ALTER SEQUENCE sequence_test_unlogged SET UNLOGGED;
+\d sequence_test_unlogged
+DROP SEQUENCE sequence_test_unlogged;
+
 -- Test sequences in read-only transactions
 CREATE TEMPORARY SEQUENCE sequence_test_temp1;
 START TRANSACTION READ ONLY;