Add CREATE SEQUENCE AS <data type> clause

This stores a data type, required to be an integer type, with the
sequence.  The sequences min and max values default to the range
supported by the type, and they cannot be set to values exceeding that
range.  The internal implementation of the sequence is not affected.

Change the serial types to create sequences of the appropriate type.
This makes sure that the min and max values of the sequence for a serial
column match the range of values supported by the table column.  So the
sequence can no longer overflow the table column.

This also makes monitoring for sequence exhaustion/wraparound easier,
which currently requires various contortions to cross-reference the
sequences with the table columns they are used with.

This commit also effectively reverts the pg_sequence column reordering
in f3b421da, because the new seqtypid
column allows us to fill the hole in the struct and create a more
natural overall column ordering.
Reviewed-by: Steve Singer <steve@ssinger.info>
Reviewed-by: Michael Paquier <michael.paquier@gmail.com>

doc/src/sgml/catalogs.sgml

@@ -5774,10 +5774,11 @@
      </row>
 
      <row>
-      <entry><structfield>seqcycle</structfield></entry>
-      <entry><type>bool</type></entry>
+      <entry><structfield>seqtypid</structfield></entry>
+      <entry><type>oid</type></entry>
+      <entry><literal><link linkend="catalog-pg-type"><structname>pg_type</structname></link>.oid</literal></entry>
       <entry></entry>
-      <entry>Whether the sequence cycles</entry>
+      <entry>Data type of the sequence</entry>
      </row>
 
      <row>
@@ -5814,6 +5815,13 @@
       <entry></entry>
       <entry>Cache size of the sequence</entry>
      </row>
+
+     <row>
+      <entry><structfield>seqcycle</structfield></entry>
+      <entry><type>bool</type></entry>
+      <entry></entry>
+      <entry>Whether the sequence cycles</entry>
+     </row>
     </tbody>
    </tgroup>
   </table>
@@ -9840,6 +9848,12 @@ SELECT * FROM pg_locks pl LEFT JOIN pg_prepared_xacts ppx
       <entry><literal><link linkend="catalog-pg-authid"><structname>pg_authid</structname></link>.rolname</literal></entry>
       <entry>Name of sequence's owner</entry>
      </row>
+     <row>
+      <entry><structfield>data_type</structfield></entry>
+      <entry><type>regtype</type></entry>
+      <entry><literal><link linkend="catalog-pg-authid"><structname>pg_type</structname></link>.oid</literal></entry>
+      <entry>Data type of the sequence</entry>
+     </row>
      <row>
       <entry><structfield>start_value</structfield></entry>
       <entry><type>bigint</type></entry>

doc/src/sgml/information_schema.sgml

@@ -4653,9 +4653,7 @@ ORDER BY c.ordinal_position;
       <entry><literal>data_type</literal></entry>
       <entry><type>character_data</type></entry>
       <entry>
-       The data type of the sequence.  In
-       <productname>PostgreSQL</productname>, this is currently always
-       <literal>bigint</literal>.
+       The data type of the sequence.
       </entry>
      </row>
 

doc/src/sgml/ref/alter_sequence.sgml

@@ -23,7 +23,9 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-ALTER SEQUENCE [ IF EXISTS ] <replaceable class="parameter">name</replaceable> [ INCREMENT [ BY ] <replaceable class="parameter">increment</replaceable> ]
+ALTER SEQUENCE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
+    [ AS <replaceable class="parameter">data_type</replaceable> ]
+    [ INCREMENT [ BY ] <replaceable class="parameter">increment</replaceable> ]
     [ MINVALUE <replaceable class="parameter">minvalue</replaceable> | NO MINVALUE ] [ MAXVALUE <replaceable class="parameter">maxvalue</replaceable> | NO MAXVALUE ]
     [ START [ WITH ] <replaceable class="parameter">start</replaceable> ]
     [ RESTART [ [ WITH ] <replaceable class="parameter">restart</replaceable> ] ]
@@ -80,6 +82,26 @@ ALTER SEQUENCE [ IF EXISTS ] <replaceable class="parameter">name</replaceable> S
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><replaceable class="parameter">data_type</replaceable></term>
+      <listitem>
+       <para>
+        The optional
+        clause <literal>AS <replaceable class="parameter">data_type</replaceable></literal>
+        changes the data type of the sequence.  Valid types are
+        are <literal>smallint</literal>, <literal>integer</literal>,
+        and <literal>bigint</literal>.
+       </para>
+
+       <para>
+        Note that changing the data type does not automatically change the
+        minimum and maximum values.  You can use the clauses <literal>NO
+        MINVALUE</literal> and <literal>NO MAXVALUE</literal> to adjust the
+        minimum and maximum values to the range of the new data type.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><replaceable class="parameter">increment</replaceable></term>
       <listitem>
@@ -102,7 +124,7 @@ ALTER SEQUENCE [ IF EXISTS ] <replaceable class="parameter">name</replaceable> S
         class="parameter">minvalue</replaceable></literal> determines
         the minimum value a sequence can generate. If <literal>NO
         MINVALUE</literal> is specified, the defaults of 1 and
-        -2<superscript>63</> for ascending and descending sequences,
+        the minimum value of the data type for ascending and descending sequences,
         respectively, will be used.  If neither option is specified,
         the current minimum value will be maintained.
        </para>
@@ -118,7 +140,7 @@ ALTER SEQUENCE [ IF EXISTS ] <replaceable class="parameter">name</replaceable> S
         class="parameter">maxvalue</replaceable></literal> determines
         the maximum value for the sequence. If <literal>NO
         MAXVALUE</literal> is specified, the defaults of
-        2<superscript>63</>-1 and -1 for ascending and descending
+        the maximum value of the data type and -1 for ascending and descending
         sequences, respectively, will be used.  If neither option is
         specified, the current maximum value will be maintained.
        </para>
@@ -300,7 +322,7 @@ ALTER SEQUENCE serial RESTART WITH 105;
 
   <para>
    <command>ALTER SEQUENCE</command> conforms to the <acronym>SQL</acronym>
-   standard, except for the <literal>START WITH</>,
+   standard, except for the <literal>AS</literal>, <literal>START WITH</>,
    <literal>OWNED BY</>, <literal>OWNER TO</>, <literal>RENAME TO</>, and
    <literal>SET SCHEMA</literal> clauses, which are
    <productname>PostgreSQL</productname> extensions.

doc/src/sgml/ref/create_sequence.sgml

@@ -21,7 +21,9 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE [ TEMPORARY | TEMP ] SEQUENCE [ IF NOT EXISTS ] <replaceable class="parameter">name</replaceable> [ INCREMENT [ BY ] <replaceable class="parameter">increment</replaceable> ]
+CREATE [ TEMPORARY | TEMP ] SEQUENCE [ IF NOT EXISTS ] <replaceable class="parameter">name</replaceable>
+    [ AS <replaceable class="parameter">data_type</replaceable> ]
+    [ INCREMENT [ BY ] <replaceable class="parameter">increment</replaceable> ]
     [ MINVALUE <replaceable class="parameter">minvalue</replaceable> | NO MINVALUE ] [ MAXVALUE <replaceable class="parameter">maxvalue</replaceable> | NO MAXVALUE ]
     [ START [ WITH ] <replaceable class="parameter">start</replaceable> ] [ CACHE <replaceable class="parameter">cache</replaceable> ] [ [ NO ] CYCLE ]
     [ OWNED BY { <replaceable class="parameter">table_name</replaceable>.<replaceable class="parameter">column_name</replaceable> | NONE } ]
@@ -110,6 +112,21 @@ SELECT * FROM <replaceable>name</replaceable>;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term><replaceable class="parameter">data_type</replaceable></term>
+    <listitem>
+     <para>
+      The optional
+      clause <literal>AS <replaceable class="parameter">data_type</replaceable></literal>
+      specifies the data type of the sequence.  Valid types are
+      are <literal>smallint</literal>, <literal>integer</literal>,
+      and <literal>bigint</literal>.  <literal>bigint</literal> is the
+      default.  The data type determines the default minimum and maximum
+      values of the sequence.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><replaceable class="parameter">increment</replaceable></term>
     <listitem>
@@ -132,9 +149,8 @@ SELECT * FROM <replaceable>name</replaceable>;
       class="parameter">minvalue</replaceable></literal> determines
       the minimum value a sequence can generate. If this clause is not
       supplied or <option>NO MINVALUE</option> is specified, then
-      defaults will be used.  The defaults are 1 and
-      -2<superscript>63</> for ascending and descending sequences,
-      respectively.
+      defaults will be used.  The default for an ascending sequence is 1.  The
+      default for a descending sequence is the minimum value of the data type.
      </para>
     </listitem>
    </varlistentry>
@@ -148,9 +164,9 @@ SELECT * FROM <replaceable>name</replaceable>;
       class="parameter">maxvalue</replaceable></literal> determines
       the maximum value for the sequence. If this clause is not
       supplied or <option>NO MAXVALUE</option> is specified, then
-      default values will be used.  The defaults are
-      2<superscript>63</>-1 and -1 for ascending and descending
-      sequences, respectively.
+      default values will be used.  The default for an ascending sequence is
+      the maximum value of the data type.  The default for a descending
+      sequence is -1.
      </para>
     </listitem>
    </varlistentry>
@@ -347,12 +363,6 @@ END;
    <command>CREATE SEQUENCE</command> conforms to the <acronym>SQL</acronym>
    standard, with the following exceptions:
    <itemizedlist>
-    <listitem>
-     <para>
-      The standard's <literal>AS <replaceable>data_type</></literal> expression is not
-      supported.
-     </para>
-    </listitem>
     <listitem>
      <para>
       Obtaining the next value is done using the <function>nextval()</>

src/backend/catalog/information_schema.sql

@@ -1531,8 +1531,8 @@ CREATE VIEW sequences AS
     SELECT CAST(current_database() AS sql_identifier) AS sequence_catalog,
            CAST(nc.nspname AS sql_identifier) AS sequence_schema,
            CAST(c.relname AS sql_identifier) AS sequence_name,
-           CAST('bigint' AS character_data) AS data_type,
-           CAST(64 AS cardinal_number) AS numeric_precision,
+           CAST(format_type(s.seqtypid, null) AS character_data) AS data_type,
+           CAST(_pg_numeric_precision(s.seqtypid, -1) AS cardinal_number) AS numeric_precision,
            CAST(2 AS cardinal_number) AS numeric_precision_radix,
            CAST(0 AS cardinal_number) AS numeric_scale,
            CAST(s.seqstart AS character_data) AS start_value,

src/backend/catalog/system_views.sql

@@ -169,6 +169,7 @@ CREATE OR REPLACE VIEW pg_sequences AS
         N.nspname AS schemaname,
         C.relname AS sequencename,
         pg_get_userbyid(C.relowner) AS sequenceowner,
+        S.seqtypid::regtype AS data_type,
         S.seqstart AS start_value,
         S.seqmin AS min_value,
         S.seqmax AS max_value,

src/backend/commands/sequence.c

@@ -34,6 +34,7 @@
 #include "funcapi.h"
 #include "miscadmin.h"
 #include "nodes/makefuncs.h"
+#include "parser/parse_type.h"
 #include "storage/lmgr.h"
 #include "storage/proc.h"
 #include "storage/smgr.h"
@@ -229,12 +230,13 @@ DefineSequence(ParseState *pstate, CreateSeqStmt *seq)
 	memset(pgs_nulls, 0, sizeof(pgs_nulls));
 
 	pgs_values[Anum_pg_sequence_seqrelid - 1] = ObjectIdGetDatum(seqoid);
-	pgs_values[Anum_pg_sequence_seqcycle - 1] = BoolGetDatum(seqform.seqcycle);
+	pgs_values[Anum_pg_sequence_seqtypid - 1] = ObjectIdGetDatum(seqform.seqtypid);
 	pgs_values[Anum_pg_sequence_seqstart - 1] = Int64GetDatumFast(seqform.seqstart);
 	pgs_values[Anum_pg_sequence_seqincrement - 1] = Int64GetDatumFast(seqform.seqincrement);
 	pgs_values[Anum_pg_sequence_seqmax - 1] = Int64GetDatumFast(seqform.seqmax);
 	pgs_values[Anum_pg_sequence_seqmin - 1] = Int64GetDatumFast(seqform.seqmin);
 	pgs_values[Anum_pg_sequence_seqcache - 1] = Int64GetDatumFast(seqform.seqcache);
+	pgs_values[Anum_pg_sequence_seqcycle - 1] = BoolGetDatum(seqform.seqcycle);
 
 	tuple = heap_form_tuple(tupDesc, pgs_values, pgs_nulls);
 	CatalogTupleInsert(rel, tuple);
@@ -622,11 +624,11 @@ nextval_internal(Oid relid)
 	if (!HeapTupleIsValid(pgstuple))
 		elog(ERROR, "cache lookup failed for sequence %u", relid);
 	pgsform = (Form_pg_sequence) GETSTRUCT(pgstuple);
-	cycle = pgsform->seqcycle;
 	incby = pgsform->seqincrement;
 	maxv = pgsform->seqmax;
 	minv = pgsform->seqmin;
 	cache = pgsform->seqcache;
+	cycle = pgsform->seqcycle;
 	ReleaseSysCache(pgstuple);
 
 	/* lock page' buffer and read tuple */
@@ -1221,6 +1223,7 @@ init_params(ParseState *pstate, List *options, bool isInit,
 			Form_pg_sequence seqform,
 			Form_pg_sequence_data seqdataform, List **owned_by)
 {
+	DefElem    *as_type = NULL;
 	DefElem    *start_value = NULL;
 	DefElem    *restart_value = NULL;
 	DefElem    *increment_by = NULL;
@@ -1236,7 +1239,16 @@ init_params(ParseState *pstate, List *options, bool isInit,
 	{
 		DefElem    *defel = (DefElem *) lfirst(option);
 
-		if (strcmp(defel->defname, "increment") == 0)
+		if (strcmp(defel->defname, "as") == 0)
+		{
+			if (as_type)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options"),
+						 parser_errposition(pstate, defel->location)));
+			as_type = defel;
+		}
+		else if (strcmp(defel->defname, "increment") == 0)
 		{
 			if (increment_by)
 				ereport(ERROR,
@@ -1320,6 +1332,20 @@ init_params(ParseState *pstate, List *options, bool isInit,
 	if (isInit)
 		seqdataform->log_cnt = 0;
 
+	/* AS type */
+	if (as_type != NULL)
+	{
+		seqform->seqtypid = typenameTypeId(pstate, defGetTypeName(as_type));
+		if (seqform->seqtypid != INT2OID &&
+			seqform->seqtypid != INT4OID &&
+			seqform->seqtypid != INT8OID)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					 errmsg("sequence type must be smallint, integer, or bigint")));
+	}
+	else if (isInit)
+		seqform->seqtypid = INT8OID;
+
 	/* INCREMENT BY */
 	if (increment_by != NULL)
 	{
@@ -1352,12 +1378,34 @@ init_params(ParseState *pstate, List *options, bool isInit,
 	else if (isInit || max_value != NULL)
 	{
 		if (seqform->seqincrement > 0)
-			seqform->seqmax = PG_INT64_MAX;		/* ascending seq */
+		{
+			/* ascending seq */
+			if (seqform->seqtypid == INT2OID)
+				seqform->seqmax = PG_INT16_MAX;
+			else if (seqform->seqtypid == INT4OID)
+				seqform->seqmax = PG_INT32_MAX;
+			else
+				seqform->seqmax = PG_INT64_MAX;
+		}
 		else
 			seqform->seqmax = -1;	/* descending seq */
 		seqdataform->log_cnt = 0;
 	}
 
+	if ((seqform->seqtypid == INT2OID && (seqform->seqmax < PG_INT16_MIN || seqform->seqmax > PG_INT16_MAX))
+		|| (seqform->seqtypid == INT4OID && (seqform->seqmax < PG_INT32_MIN || seqform->seqmax > PG_INT32_MAX))
+		|| (seqform->seqtypid == INT8OID && (seqform->seqmax < PG_INT64_MIN || seqform->seqmax > PG_INT64_MAX)))
+	{
+		char		bufx[100];
+
+		snprintf(bufx, sizeof(bufx), INT64_FORMAT, seqform->seqmax);
+
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("MAXVALUE (%s) is out of range for sequence data type %s",
+						bufx, format_type_be(seqform->seqtypid))));
+	}
+
 	/* MINVALUE (null arg means NO MINVALUE) */
 	if (min_value != NULL && min_value->arg)
 	{
@@ -1369,10 +1417,32 @@ init_params(ParseState *pstate, List *options, bool isInit,
 		if (seqform->seqincrement > 0)
 			seqform->seqmin = 1; /* ascending seq */
 		else
-			seqform->seqmin = PG_INT64_MIN;		/* descending seq */
+		{
+			/* descending seq */
+			if (seqform->seqtypid == INT2OID)
+				seqform->seqmin = PG_INT16_MIN;
+			else if (seqform->seqtypid == INT4OID)
+				seqform->seqmin = PG_INT32_MIN;
+			else
+				seqform->seqmin = PG_INT64_MIN;
+		}
 		seqdataform->log_cnt = 0;
 	}
 
+	if ((seqform->seqtypid == INT2OID && (seqform->seqmin < PG_INT16_MIN || seqform->seqmin > PG_INT16_MAX))
+		|| (seqform->seqtypid == INT4OID && (seqform->seqmin < PG_INT32_MIN || seqform->seqmin > PG_INT32_MAX))
+		|| (seqform->seqtypid == INT8OID && (seqform->seqmin < PG_INT64_MIN || seqform->seqmin > PG_INT64_MAX)))
+	{
+		char		bufm[100];
+
+		snprintf(bufm, sizeof(bufm), INT64_FORMAT, seqform->seqmin);
+
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("MINVALUE (%s) is out of range for sequence data type %s",
+						bufm, format_type_be(seqform->seqtypid))));
+	}
+
 	/* crosscheck min/max */
 	if (seqform->seqmin >= seqform->seqmax)
 	{
@@ -1590,8 +1660,8 @@ pg_sequence_parameters(PG_FUNCTION_ARGS)
 {
 	Oid			relid = PG_GETARG_OID(0);
 	TupleDesc	tupdesc;
-	Datum		values[6];
-	bool		isnull[6];
+	Datum		values[7];
+	bool		isnull[7];
 	HeapTuple	pgstuple;
 	Form_pg_sequence pgsform;
 
@@ -1601,7 +1671,7 @@ pg_sequence_parameters(PG_FUNCTION_ARGS)
 				 errmsg("permission denied for sequence %s",
 						get_rel_name(relid))));
 
-	tupdesc = CreateTemplateTupleDesc(6, false);
+	tupdesc = CreateTemplateTupleDesc(7, false);
 	TupleDescInitEntry(tupdesc, (AttrNumber) 1, "start_value",
 					   INT8OID, -1, 0);
 	TupleDescInitEntry(tupdesc, (AttrNumber) 2, "minimum_value",
@@ -1614,6 +1684,8 @@ pg_sequence_parameters(PG_FUNCTION_ARGS)
 					   BOOLOID, -1, 0);
 	TupleDescInitEntry(tupdesc, (AttrNumber) 6, "cache_size",
 					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 7, "data_type",
+					   OIDOID, -1, 0);
 
 	BlessTupleDesc(tupdesc);
 
@@ -1630,6 +1702,7 @@ pg_sequence_parameters(PG_FUNCTION_ARGS)
 	values[3] = Int64GetDatum(pgsform->seqincrement);
 	values[4] = BoolGetDatum(pgsform->seqcycle);
 	values[5] = Int64GetDatum(pgsform->seqcache);
+	values[6] = ObjectIdGetDatum(pgsform->seqtypid);
 
 	ReleaseSysCache(pgstuple);
 

src/backend/parser/gram.y

@@ -3941,7 +3941,11 @@ SeqOptList: SeqOptElem								{ $$ = list_make1($1); }
 			| SeqOptList SeqOptElem					{ $$ = lappend($1, $2); }
 		;
 
-SeqOptElem: CACHE NumericOnly
+SeqOptElem: AS SimpleTypename
+				{
+					$$ = makeDefElem("as", (Node *)$2, @1);
+				}
+			| CACHE NumericOnly
 				{
 					$$ = makeDefElem("cache", (Node *)$2, @1);
 				}

src/backend/parser/parse_utilcmd.c

@@ -469,7 +469,7 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 		 */
 		seqstmt = makeNode(CreateSeqStmt);
 		seqstmt->sequence = makeRangeVar(snamespace, sname, -1);
-		seqstmt->options = NIL;
+		seqstmt->options = list_make1(makeDefElem("as", (Node *) makeTypeNameFromOid(column->typeName->typeOid, -1), -1));
 
 		/*
 		 * If this is ALTER ADD COLUMN, make sure the sequence will be owned

src/bin/pg_dump/pg_dump.c

@@ -15912,39 +15912,29 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 	PGresult   *res;
 	char	   *startv,
 			   *incby,
-			   *maxv = NULL,
-			   *minv = NULL,
-			   *cache;
-	char		bufm[100],
-				bufx[100];
+			   *maxv,
+			   *minv,
+			   *cache,
+			   *seqtype;
 	bool		cycled;
+	bool		is_ascending;
 	PQExpBuffer query = createPQExpBuffer();
 	PQExpBuffer delqry = createPQExpBuffer();
 	PQExpBuffer labelq = createPQExpBuffer();
 
-	snprintf(bufm, sizeof(bufm), INT64_FORMAT, PG_INT64_MIN);
-	snprintf(bufx, sizeof(bufx), INT64_FORMAT, PG_INT64_MAX);
-
 	if (fout->remoteVersion >= 100000)
 	{
 		/* Make sure we are in proper schema */
 		selectSourceSchema(fout, "pg_catalog");
 
 		appendPQExpBuffer(query,
-						  "SELECT seqstart, seqincrement, "
-						  "CASE WHEN seqincrement > 0 AND seqmax = %s THEN NULL "
-						  "     WHEN seqincrement < 0 AND seqmax = -1 THEN NULL "
-						  "     ELSE seqmax "
-						  "END AS seqmax, "
-						  "CASE WHEN seqincrement > 0 AND seqmin = 1 THEN NULL "
-						  "     WHEN seqincrement < 0 AND seqmin = %s THEN NULL "
-						  "     ELSE seqmin "
-						  "END AS seqmin, "
+						  "SELECT format_type(seqtypid, NULL), "
+						  "seqstart, seqincrement, "
+						  "seqmax, seqmin, "
 						  "seqcache, seqcycle "
 						  "FROM pg_class c "
 						  "JOIN pg_sequence s ON (s.seqrelid = c.oid) "
 						  "WHERE c.oid = '%u'::oid",
-						  bufx, bufm,
 						  tbinfo->dobj.catId.oid);
 	}
 	else if (fout->remoteVersion >= 80400)
@@ -15958,17 +15948,9 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 		selectSourceSchema(fout, tbinfo->dobj.namespace->dobj.name);
 
 		appendPQExpBuffer(query,
-						  "SELECT start_value, increment_by, "
-				   "CASE WHEN increment_by > 0 AND max_value = %s THEN NULL "
-				   "     WHEN increment_by < 0 AND max_value = -1 THEN NULL "
-						  "     ELSE max_value "
-						  "END AS max_value, "
-					"CASE WHEN increment_by > 0 AND min_value = 1 THEN NULL "
-				   "     WHEN increment_by < 0 AND min_value = %s THEN NULL "
-						  "     ELSE min_value "
-						  "END AS min_value, "
+						  "SELECT 'bigint'::name AS sequence_type, "
+						  "start_value, increment_by, max_value, min_value, "
 						  "cache_value, is_cycled FROM %s",
-						  bufx, bufm,
 						  fmtId(tbinfo->dobj.name));
 	}
 	else
@@ -15977,17 +15959,9 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 		selectSourceSchema(fout, tbinfo->dobj.namespace->dobj.name);
 
 		appendPQExpBuffer(query,
-						  "SELECT 0 AS start_value, increment_by, "
-				   "CASE WHEN increment_by > 0 AND max_value = %s THEN NULL "
-				   "     WHEN increment_by < 0 AND max_value = -1 THEN NULL "
-						  "     ELSE max_value "
-						  "END AS max_value, "
-					"CASE WHEN increment_by > 0 AND min_value = 1 THEN NULL "
-				   "     WHEN increment_by < 0 AND min_value = %s THEN NULL "
-						  "     ELSE min_value "
-						  "END AS min_value, "
+						  "SELECT 'bigint'::name AS sequence_type, "
+						  "0 AS start_value, increment_by, max_value, min_value, "
 						  "cache_value, is_cycled FROM %s",
-						  bufx, bufm,
 						  fmtId(tbinfo->dobj.name));
 	}
 
@@ -16002,14 +15976,48 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 		exit_nicely(1);
 	}
 
-	startv = PQgetvalue(res, 0, 0);
-	incby = PQgetvalue(res, 0, 1);
-	if (!PQgetisnull(res, 0, 2))
-		maxv = PQgetvalue(res, 0, 2);
-	if (!PQgetisnull(res, 0, 3))
-		minv = PQgetvalue(res, 0, 3);
-	cache = PQgetvalue(res, 0, 4);
-	cycled = (strcmp(PQgetvalue(res, 0, 5), "t") == 0);
+	seqtype = PQgetvalue(res, 0, 0);
+	startv = PQgetvalue(res, 0, 1);
+	incby = PQgetvalue(res, 0, 2);
+	maxv = PQgetvalue(res, 0, 3);
+	minv = PQgetvalue(res, 0, 4);
+	cache = PQgetvalue(res, 0, 5);
+	cycled = (strcmp(PQgetvalue(res, 0, 6), "t") == 0);
+
+	is_ascending = incby[0] != '-';
+
+	if (is_ascending && atoi(minv) == 1)
+		minv = NULL;
+	if (!is_ascending && atoi(maxv) == -1)
+		maxv = NULL;
+
+	if (strcmp(seqtype, "smallint") == 0)
+	{
+		if (!is_ascending && atoi(minv) == PG_INT16_MIN)
+			minv = NULL;
+		if (is_ascending && atoi(maxv) == PG_INT16_MAX)
+			maxv = NULL;
+	}
+	else if (strcmp(seqtype, "integer") == 0)
+	{
+		if (!is_ascending && atoi(minv) == PG_INT32_MIN)
+			minv = NULL;
+		if (is_ascending && atoi(maxv) == PG_INT32_MAX)
+			maxv = NULL;
+	}
+	else if (strcmp(seqtype, "bigint") == 0)
+	{
+		char		bufm[100],
+					bufx[100];
+
+		snprintf(bufm, sizeof(bufm), INT64_FORMAT, PG_INT64_MIN);
+		snprintf(bufx, sizeof(bufx), INT64_FORMAT, PG_INT64_MAX);
+
+		if (!is_ascending && strcmp(minv, bufm) == 0)
+			minv = NULL;
+		if (is_ascending && strcmp(maxv, bufx) == 0)
+			maxv = NULL;
+	}
 
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
@@ -16033,6 +16041,9 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 					  "CREATE SEQUENCE %s\n",
 					  fmtId(tbinfo->dobj.name));
 
+	if (strcmp(seqtype, "bigint") != 0)
+		appendPQExpBuffer(query, "    AS %s\n", seqtype);
+
 	if (fout->remoteVersion >= 80400)
 		appendPQExpBuffer(query, "    START WITH %s\n", startv);
 

src/bin/pg_dump/t/002_pg_dump.pl

@@ -2494,6 +2494,7 @@ qr/CREATE TRANSFORM FOR integer LANGUAGE sql \(FROM SQL WITH FUNCTION pg_catalog
 		catch_all => 'CREATE ... commands',
 		regexp    => qr/^
 			\QCREATE SEQUENCE test_table_col1_seq\E
+			\n\s+\QAS integer\E
 			\n\s+\QSTART WITH 1\E
 			\n\s+\QINCREMENT BY 1\E
 			\n\s+\QNO MINVALUE\E
@@ -2529,6 +2530,7 @@ qr/CREATE TRANSFORM FOR integer LANGUAGE sql \(FROM SQL WITH FUNCTION pg_catalog
 		catch_all => 'CREATE ... commands',
 		regexp    => qr/^
 			\QCREATE SEQUENCE test_third_table_col1_seq\E
+			\n\s+\QAS integer\E
 			\n\s+\QSTART WITH 1\E
 			\n\s+\QINCREMENT BY 1\E
 			\n\s+\QNO MINVALUE\E

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	201701309
+#define CATALOG_VERSION_NO	201702101
 
 #endif

src/include/catalog/pg_proc.h

@@ -1766,7 +1766,7 @@ DATA(insert OID = 1576 (  setval			PGNSP PGUID 12 1 0 0 0 f f f f t f v u 2 0 20
 DESCR("set sequence value");
 DATA(insert OID = 1765 (  setval			PGNSP PGUID 12 1 0 0 0 f f f f t f v u 3 0 20 "2205 20 16" _null_ _null_ _null_ _null_ _null_ setval3_oid _null_ _null_ _null_ ));
 DESCR("set sequence value and is_called status");
-DATA(insert OID = 3078 (  pg_sequence_parameters	PGNSP PGUID 12 1 0 0 0 f f f f t f s s 1 0 2249 "26" "{26,20,20,20,20,16,20}" "{i,o,o,o,o,o,o}" "{sequence_oid,start_value,minimum_value,maximum_value,increment,cycle_option,cache_size}" _null_ _null_ pg_sequence_parameters _null_ _null_ _null_));
+DATA(insert OID = 3078 (  pg_sequence_parameters	PGNSP PGUID 12 1 0 0 0 f f f f t f s s 1 0 2249 "26" "{26,20,20,20,20,16,20,26}" "{i,o,o,o,o,o,o,o}" "{sequence_oid,start_value,minimum_value,maximum_value,increment,cycle_option,cache_size,data_type}" _null_ _null_ pg_sequence_parameters _null_ _null_ _null_));
 DESCR("sequence parameters, for use by information schema");
 DATA(insert OID = 4032 ( pg_sequence_last_value		PGNSP PGUID 12 1 0 0 0 f f f f t f v u 1 0 20 "2205" _null_ _null_ _null_ _null_ _null_	pg_sequence_last_value _null_ _null_ _null_ ));
 DESCR("sequence last value");

src/include/catalog/pg_sequence.h

@@ -8,23 +8,25 @@
 CATALOG(pg_sequence,2224) BKI_WITHOUT_OIDS
 {
 	Oid			seqrelid;
-	bool		seqcycle;
+	Oid			seqtypid;
 	int64		seqstart;
 	int64		seqincrement;
 	int64		seqmax;
 	int64		seqmin;
 	int64		seqcache;
+	bool		seqcycle;
 } FormData_pg_sequence;
 
 typedef FormData_pg_sequence *Form_pg_sequence;
 
-#define Natts_pg_sequence				7
+#define Natts_pg_sequence				8
 #define Anum_pg_sequence_seqrelid		1
-#define Anum_pg_sequence_seqcycle		2
+#define Anum_pg_sequence_seqtypid		2
 #define Anum_pg_sequence_seqstart		3
 #define Anum_pg_sequence_seqincrement	4
 #define Anum_pg_sequence_seqmax			5
 #define Anum_pg_sequence_seqmin			6
 #define Anum_pg_sequence_seqcache		7
+#define Anum_pg_sequence_seqcycle		8
 
 #endif	/* PG_SEQUENCE_H */

src/test/modules/test_pg_dump/t/001_base.pl

@@ -241,6 +241,7 @@ my %tests = (
 	'CREATE SEQUENCE regress_pg_dump_table_col1_seq' => {
 		regexp => qr/^
                     \QCREATE SEQUENCE regress_pg_dump_table_col1_seq\E
+                    \n\s+\QAS integer\E
                     \n\s+\QSTART WITH 1\E
                     \n\s+\QINCREMENT BY 1\E
                     \n\s+\QNO MINVALUE\E

src/test/regress/expected/rules.out

@@ -1641,6 +1641,7 @@ UNION ALL
 pg_sequences| SELECT n.nspname AS schemaname,
     c.relname AS sequencename,
     pg_get_userbyid(c.relowner) AS sequenceowner,
+    (s.seqtypid)::regtype AS data_type,
     s.seqstart AS start_value,
     s.seqmin AS min_value,
     s.seqmax AS max_value,

src/test/regress/expected/sequence.out

@@ -28,6 +28,23 @@ CREATE TABLE sequence_test_table (a int);
 CREATE SEQUENCE sequence_testx OWNED BY sequence_test_table.b;  -- wrong column
 ERROR:  column "b" of relation "sequence_test_table" does not exist
 DROP TABLE sequence_test_table;
+-- sequence data types
+CREATE SEQUENCE sequence_test5 AS integer;
+CREATE SEQUENCE sequence_test6 AS smallint;
+CREATE SEQUENCE sequence_test7 AS bigint;
+CREATE SEQUENCE sequence_testx AS text;
+ERROR:  sequence type must be smallint, integer, or bigint
+CREATE SEQUENCE sequence_testx AS nosuchtype;
+ERROR:  type "nosuchtype" does not exist
+LINE 1: CREATE SEQUENCE sequence_testx AS nosuchtype;
+                                          ^
+ALTER SEQUENCE sequence_test5 AS smallint;  -- fails
+ERROR:  MAXVALUE (2147483647) is out of range for sequence data type smallint
+ALTER SEQUENCE sequence_test5 AS smallint NO MINVALUE NO MAXVALUE;
+CREATE SEQUENCE sequence_testx AS smallint MAXVALUE 100000;
+ERROR:  MAXVALUE (100000) is out of range for sequence data type smallint
+CREATE SEQUENCE sequence_testx AS smallint MINVALUE -100000;
+ERROR:  MINVALUE (-100000) is out of range for sequence data type smallint
 ---
 --- test creation of SERIAL column
 ---
@@ -445,13 +462,16 @@ SELECT * FROM information_schema.sequences
  regression       | public          | sequence_test2     | bigint    |                64 |                       2 |             0 | 32          | 5                    | 36                  | 4         | YES
  regression       | public          | sequence_test3     | bigint    |                64 |                       2 |             0 | 1           | 1                    | 9223372036854775807 | 1         | NO
  regression       | public          | sequence_test4     | bigint    |                64 |                       2 |             0 | -1          | -9223372036854775808 | -1                  | -1        | NO
- regression       | public          | serialtest1_f2_foo | bigint    |                64 |                       2 |             0 | 1           | 1                    | 9223372036854775807 | 1         | NO
- regression       | public          | serialtest2_f2_seq | bigint    |                64 |                       2 |             0 | 1           | 1                    | 9223372036854775807 | 1         | NO
- regression       | public          | serialtest2_f3_seq | bigint    |                64 |                       2 |             0 | 1           | 1                    | 9223372036854775807 | 1         | NO
- regression       | public          | serialtest2_f4_seq | bigint    |                64 |                       2 |             0 | 1           | 1                    | 9223372036854775807 | 1         | NO
+ regression       | public          | sequence_test5     | smallint  |                16 |                       2 |             0 | 1           | 1                    | 32767               | 1         | NO
+ regression       | public          | sequence_test6     | smallint  |                16 |                       2 |             0 | 1           | 1                    | 32767               | 1         | NO
+ regression       | public          | sequence_test7     | bigint    |                64 |                       2 |             0 | 1           | 1                    | 9223372036854775807 | 1         | NO
+ regression       | public          | serialtest1_f2_foo | integer   |                32 |                       2 |             0 | 1           | 1                    | 2147483647          | 1         | NO
+ regression       | public          | serialtest2_f2_seq | integer   |                32 |                       2 |             0 | 1           | 1                    | 2147483647          | 1         | NO
+ regression       | public          | serialtest2_f3_seq | smallint  |                16 |                       2 |             0 | 1           | 1                    | 32767               | 1         | NO
+ regression       | public          | serialtest2_f4_seq | smallint  |                16 |                       2 |             0 | 1           | 1                    | 32767               | 1         | NO
  regression       | public          | serialtest2_f5_seq | bigint    |                64 |                       2 |             0 | 1           | 1                    | 9223372036854775807 | 1         | NO
  regression       | public          | serialtest2_f6_seq | bigint    |                64 |                       2 |             0 | 1           | 1                    | 9223372036854775807 | 1         | NO
-(9 rows)
+(12 rows)
 
 SELECT schemaname, sequencename, start_value, min_value, max_value, increment_by, cycle, cache_size, last_value
 FROM pg_sequences
@@ -462,18 +482,21 @@ WHERE sequencename ~ ANY(ARRAY['sequence_test', 'serialtest'])
  public     | sequence_test2     |          32 |                    5 |                  36 |            4 | t     |          1 |          5
  public     | sequence_test3     |           1 |                    1 | 9223372036854775807 |            1 | f     |          1 |           
  public     | sequence_test4     |          -1 | -9223372036854775808 |                  -1 |           -1 | f     |          1 |         -1
- public     | serialtest1_f2_foo |           1 |                    1 | 9223372036854775807 |            1 | f     |          1 |          3
- public     | serialtest2_f2_seq |           1 |                    1 | 9223372036854775807 |            1 | f     |          1 |          2
- public     | serialtest2_f3_seq |           1 |                    1 | 9223372036854775807 |            1 | f     |          1 |          2
- public     | serialtest2_f4_seq |           1 |                    1 | 9223372036854775807 |            1 | f     |          1 |          2
+ public     | sequence_test5     |           1 |                    1 |               32767 |            1 | f     |          1 |           
+ public     | sequence_test6     |           1 |                    1 |               32767 |            1 | f     |          1 |           
+ public     | sequence_test7     |           1 |                    1 | 9223372036854775807 |            1 | f     |          1 |           
+ public     | serialtest1_f2_foo |           1 |                    1 |          2147483647 |            1 | f     |          1 |          3
+ public     | serialtest2_f2_seq |           1 |                    1 |          2147483647 |            1 | f     |          1 |          2
+ public     | serialtest2_f3_seq |           1 |                    1 |               32767 |            1 | f     |          1 |          2
+ public     | serialtest2_f4_seq |           1 |                    1 |               32767 |            1 | f     |          1 |          2
  public     | serialtest2_f5_seq |           1 |                    1 | 9223372036854775807 |            1 | f     |          1 |          2
  public     | serialtest2_f6_seq |           1 |                    1 | 9223372036854775807 |            1 | f     |          1 |          2
-(9 rows)
+(12 rows)
 
 SELECT * FROM pg_sequence_parameters('sequence_test4'::regclass);
- start_value |    minimum_value     | maximum_value | increment | cycle_option | cache_size 
--------------+----------------------+---------------+-----------+--------------+------------
-          -1 | -9223372036854775808 |            -1 |        -1 | f            |          1
+ start_value |    minimum_value     | maximum_value | increment | cycle_option | cache_size | data_type 
+-------------+----------------------+---------------+-----------+--------------+------------+-----------
+          -1 | -9223372036854775808 |            -1 |        -1 | f            |          1 |        20
 (1 row)
 
 -- Test comments

src/test/regress/sql/sequence.sql

@@ -19,6 +19,19 @@ CREATE TABLE sequence_test_table (a int);
 CREATE SEQUENCE sequence_testx OWNED BY sequence_test_table.b;  -- wrong column
 DROP TABLE sequence_test_table;
 
+-- sequence data types
+CREATE SEQUENCE sequence_test5 AS integer;
+CREATE SEQUENCE sequence_test6 AS smallint;
+CREATE SEQUENCE sequence_test7 AS bigint;
+CREATE SEQUENCE sequence_testx AS text;
+CREATE SEQUENCE sequence_testx AS nosuchtype;
+
+ALTER SEQUENCE sequence_test5 AS smallint;  -- fails
+ALTER SEQUENCE sequence_test5 AS smallint NO MINVALUE NO MAXVALUE;
+
+CREATE SEQUENCE sequence_testx AS smallint MAXVALUE 100000;
+CREATE SEQUENCE sequence_testx AS smallint MINVALUE -100000;
+
 ---
 --- test creation of SERIAL column
 ---