Add SQL type xid8 to expose FullTransactionId to users.

Similar to xid, but 64 bits wide.  This new type is suitable for use in
various system views and administration functions.
Reviewed-by: Fujii Masao <masao.fujii@oss.nttdata.com>
Reviewed-by: Takao Fujii <btfujiitkp@oss.nttdata.com>
Reviewed-by: Yoshikazu Imai <imai.yoshikazu@fujitsu.com>
Reviewed-by: Mark Dilger <mark.dilger@enterprisedb.com>
Discussion: https://postgr.es/m/20190725000636.666m5mad25wfbrri%40alap3.anarazel.de

doc/src/sgml/datatype.sgml

@@ -4516,6 +4516,10 @@ INSERT INTO mytable VALUES(-1);  -- fails
     <primary>regtype</primary>
    </indexterm>
 
+   <indexterm zone="datatype-oid">
+    <primary>xid8</primary>
+   </indexterm>
+
    <indexterm zone="datatype-oid">
     <primary>cid</primary>
    </indexterm>
@@ -4719,6 +4723,9 @@ SELECT * FROM pg_attribute
     Another identifier type used by the system is <type>xid</type>, or transaction
     (abbreviated <abbrev>xact</abbrev>) identifier.  This is the data type of the system columns
     <structfield>xmin</structfield> and <structfield>xmax</structfield>.  Transaction identifiers are 32-bit quantities.
+    In some contexts, a 64-bit variant <type>xid8</type> is used.  Unlike
+    <type>xid</type> values, <type>xid8</type> values increase strictly
+    monotonically and cannot be reused in the lifetime of a database cluster.
    </para>
 
    <para>

src/backend/access/hash/hashvalidate.c

@@ -317,6 +317,9 @@ check_hash_func_signature(Oid funcid, int16 amprocnum, Oid argtype)
 			(argtype == DATEOID ||
 			 argtype == XIDOID || argtype == CIDOID))
 			 /* okay, allowed use of hashint4() */ ;
+		else if ((funcid == F_HASHINT8 || funcid == F_HASHINT8EXTENDED) &&
+			(argtype == XID8OID))
+			 /* okay, allowed use of hashint8() */ ;
 		else if ((funcid == F_TIMESTAMP_HASH ||
 				  funcid == F_TIMESTAMP_HASH_EXTENDED) &&
 				 argtype == TIMESTAMPTZOID)

src/backend/utils/adt/xid.c

@@ -21,6 +21,7 @@
 #include "access/xact.h"
 #include "libpq/pqformat.h"
 #include "utils/builtins.h"
+#include "utils/xid8.h"
 
 #define PG_GETARG_TRANSACTIONID(n)	DatumGetTransactionId(PG_GETARG_DATUM(n))
 #define PG_RETURN_TRANSACTIONID(x)	return TransactionIdGetDatum(x)
@@ -147,6 +148,121 @@ xidComparator(const void *arg1, const void *arg2)
 	return 0;
 }
 
+Datum
+xid8toxid(PG_FUNCTION_ARGS)
+{
+	FullTransactionId fxid = PG_GETARG_FULLTRANSACTIONID(0);
+
+	PG_RETURN_TRANSACTIONID(XidFromFullTransactionId(fxid));
+}
+
+Datum
+xid8in(PG_FUNCTION_ARGS)
+{
+	char	   *str = PG_GETARG_CSTRING(0);
+
+	PG_RETURN_FULLTRANSACTIONID(FullTransactionIdFromU64(pg_strtouint64(str, NULL, 0)));
+}
+
+Datum
+xid8out(PG_FUNCTION_ARGS)
+{
+	FullTransactionId fxid = PG_GETARG_FULLTRANSACTIONID(0);
+	char	   *result = (char *) palloc(21);
+
+	snprintf(result, 21, UINT64_FORMAT, U64FromFullTransactionId(fxid));
+	PG_RETURN_CSTRING(result);
+}
+
+Datum
+xid8recv(PG_FUNCTION_ARGS)
+{
+	StringInfo	buf = (StringInfo) PG_GETARG_POINTER(0);
+	uint64		value;
+
+	value = (uint64) pq_getmsgint64(buf);
+	PG_RETURN_FULLTRANSACTIONID(FullTransactionIdFromU64(value));
+}
+
+Datum
+xid8send(PG_FUNCTION_ARGS)
+{
+	FullTransactionId arg1 = PG_GETARG_FULLTRANSACTIONID(0);
+	StringInfoData buf;
+
+	pq_begintypsend(&buf);
+	pq_sendint64(&buf, (uint64) U64FromFullTransactionId(arg1));
+	PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
+}
+
+Datum
+xid8eq(PG_FUNCTION_ARGS)
+{
+	FullTransactionId fxid1 = PG_GETARG_FULLTRANSACTIONID(0);
+	FullTransactionId fxid2 = PG_GETARG_FULLTRANSACTIONID(1);
+
+	PG_RETURN_BOOL(FullTransactionIdEquals(fxid1, fxid2));
+}
+
+Datum
+xid8ne(PG_FUNCTION_ARGS)
+{
+	FullTransactionId fxid1 = PG_GETARG_FULLTRANSACTIONID(0);
+	FullTransactionId fxid2 = PG_GETARG_FULLTRANSACTIONID(1);
+
+	PG_RETURN_BOOL(!FullTransactionIdEquals(fxid1, fxid2));
+}
+
+Datum
+xid8lt(PG_FUNCTION_ARGS)
+{
+	FullTransactionId fxid1 = PG_GETARG_FULLTRANSACTIONID(0);
+	FullTransactionId fxid2 = PG_GETARG_FULLTRANSACTIONID(1);
+
+	PG_RETURN_BOOL(FullTransactionIdPrecedes(fxid1, fxid2));
+}
+
+Datum
+xid8gt(PG_FUNCTION_ARGS)
+{
+	FullTransactionId fxid1 = PG_GETARG_FULLTRANSACTIONID(0);
+	FullTransactionId fxid2 = PG_GETARG_FULLTRANSACTIONID(1);
+
+	PG_RETURN_BOOL(FullTransactionIdFollows(fxid1, fxid2));
+}
+
+Datum
+xid8le(PG_FUNCTION_ARGS)
+{
+	FullTransactionId fxid1 = PG_GETARG_FULLTRANSACTIONID(0);
+	FullTransactionId fxid2 = PG_GETARG_FULLTRANSACTIONID(1);
+
+	PG_RETURN_BOOL(FullTransactionIdPrecedesOrEquals(fxid1, fxid2));
+}
+
+Datum
+xid8ge(PG_FUNCTION_ARGS)
+{
+	FullTransactionId fxid1 = PG_GETARG_FULLTRANSACTIONID(0);
+	FullTransactionId fxid2 = PG_GETARG_FULLTRANSACTIONID(1);
+
+	PG_RETURN_BOOL(FullTransactionIdFollowsOrEquals(fxid1, fxid2));
+}
+
+Datum
+xid8cmp(PG_FUNCTION_ARGS)
+{
+	FullTransactionId fxid1 = PG_GETARG_FULLTRANSACTIONID(0);
+	FullTransactionId fxid2 = PG_GETARG_FULLTRANSACTIONID(1);
+
+	if (FullTransactionIdFollows(fxid1, fxid2))
+		PG_RETURN_INT32(1);
+	else if (FullTransactionIdEquals(fxid1, fxid2))
+		PG_RETURN_INT32(0);
+	else
+		PG_RETURN_INT32(-1);
+}
+
 /*****************************************************************************
  *	 COMMAND IDENTIFIER ROUTINES											 *
  *****************************************************************************/

src/fe_utils/print.c

@@ -3509,6 +3509,7 @@ column_type_alignment(Oid ftype)
 		case NUMERICOID:
 		case OIDOID:
 		case XIDOID:
+		case XID8OID:
 		case CIDOID:
 		case CASHOID:
 			align = 'r';

src/include/access/transam.h

@@ -47,7 +47,11 @@
 #define EpochFromFullTransactionId(x)	((uint32) ((x).value >> 32))
 #define XidFromFullTransactionId(x)		((uint32) (x).value)
 #define U64FromFullTransactionId(x)		((x).value)
+#define FullTransactionIdEquals(a, b)	((a).value == (b).value)
 #define FullTransactionIdPrecedes(a, b)	((a).value < (b).value)
+#define FullTransactionIdPrecedesOrEquals(a, b) ((a).value <= (b).value)
+#define FullTransactionIdFollows(a, b) ((a).value > (b).value)
+#define FullTransactionIdFollowsOrEquals(a, b) ((a).value >= (b).value)
 #define FullTransactionIdIsValid(x)		TransactionIdIsValid(XidFromFullTransactionId(x))
 #define InvalidFullTransactionId		FullTransactionIdFromEpochAndXid(0, InvalidTransactionId)
 
@@ -71,6 +75,16 @@ FullTransactionIdFromEpochAndXid(uint32 epoch, TransactionId xid)
 	return result;
 }
 
+static inline FullTransactionId
+FullTransactionIdFromU64(uint64 value)
+{
+	FullTransactionId result;
+
+	result.value = value;
+
+	return result;
+}
+
 /* advance a transaction ID variable, handling wraparound correctly */
 #define TransactionIdAdvance(dest)	\
 	do { \

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	202004022
+#define CATALOG_VERSION_NO	202004061
 
 #endif

src/include/catalog/pg_amop.dat

@@ -180,6 +180,24 @@
 { amopfamily => 'btree/oid_ops', amoplefttype => 'oid', amoprighttype => 'oid',
   amopstrategy => '5', amopopr => '>(oid,oid)', amopmethod => 'btree' },
 
+# btree xid8_ops
+
+{ amopfamily => 'btree/xid8_ops', amoplefttype => 'xid8',
+  amoprighttype => 'xid8', amopstrategy => '1', amopopr => '<(xid8,xid8)',
+  amopmethod => 'btree' },
+{ amopfamily => 'btree/xid8_ops', amoplefttype => 'xid8',
+  amoprighttype => 'xid8', amopstrategy => '2', amopopr => '<=(xid8,xid8)',
+  amopmethod => 'btree' },
+{ amopfamily => 'btree/xid8_ops', amoplefttype => 'xid8',
+  amoprighttype => 'xid8', amopstrategy => '3', amopopr => '=(xid8,xid8)',
+  amopmethod => 'btree' },
+{ amopfamily => 'btree/xid8_ops', amoplefttype => 'xid8',
+  amoprighttype => 'xid8', amopstrategy => '4', amopopr => '>=(xid8,xid8)',
+  amopmethod => 'btree' },
+{ amopfamily => 'btree/xid8_ops', amoplefttype => 'xid8',
+  amoprighttype => 'xid8', amopstrategy => '5', amopopr => '>(xid8,xid8)',
+  amopmethod => 'btree' },
+
 # btree tid_ops
 
 { amopfamily => 'btree/tid_ops', amoplefttype => 'tid', amoprighttype => 'tid',
@@ -1009,6 +1027,10 @@
 { amopfamily => 'hash/xid_ops', amoplefttype => 'xid', amoprighttype => 'xid',
   amopstrategy => '1', amopopr => '=(xid,xid)', amopmethod => 'hash' },
 
+# xid8_ops
+{ amopfamily => 'hash/xid8_ops', amoplefttype => 'xid8', amoprighttype => 'xid8',
+  amopstrategy => '1', amopopr => '=(xid8,xid8)', amopmethod => 'hash' },
+
 # cid_ops
 { amopfamily => 'hash/cid_ops', amoplefttype => 'cid', amoprighttype => 'cid',
   amopstrategy => '1', amopopr => '=(cid,cid)', amopmethod => 'hash' },

src/include/catalog/pg_amproc.dat

@@ -287,6 +287,10 @@
   amprocrighttype => 'anyrange', amprocnum => '1', amproc => 'range_cmp' },
 { amprocfamily => 'btree/jsonb_ops', amproclefttype => 'jsonb',
   amprocrighttype => 'jsonb', amprocnum => '1', amproc => 'jsonb_cmp' },
+{ amprocfamily => 'btree/xid8_ops', amproclefttype => 'xid8',
+  amprocrighttype => 'xid8', amprocnum => '1', amproc => 'xid8cmp' },
+{ amprocfamily => 'btree/xid8_ops', amproclefttype => 'xid8',
+  amprocrighttype => 'xid8', amprocnum => '4', amproc => 'btequalimage' },
 
 # hash
 { amprocfamily => 'hash/bpchar_ops', amproclefttype => 'bpchar',
@@ -399,6 +403,10 @@
   amprocrighttype => 'xid', amprocnum => '1', amproc => 'hashint4' },
 { amprocfamily => 'hash/xid_ops', amproclefttype => 'xid',
   amprocrighttype => 'xid', amprocnum => '2', amproc => 'hashint4extended' },
+{ amprocfamily => 'hash/xid8_ops', amproclefttype => 'xid8',
+  amprocrighttype => 'xid8', amprocnum => '1', amproc => 'hashint8' },
+{ amprocfamily => 'hash/xid8_ops', amproclefttype => 'xid8',
+  amprocrighttype => 'xid8', amprocnum => '2', amproc => 'hashint8extended' },
 { amprocfamily => 'hash/cid_ops', amproclefttype => 'cid',
   amprocrighttype => 'cid', amprocnum => '1', amproc => 'hashint4' },
 { amprocfamily => 'hash/cid_ops', amproclefttype => 'cid',

src/include/catalog/pg_cast.dat

@@ -93,6 +93,10 @@
 { castsource => 'bool', casttarget => 'int4', castfunc => 'int4(bool)',
   castcontext => 'e', castmethod => 'f' },
 
+# Allow explicit coercions between xid8 and xid
+{ castsource => 'xid8', casttarget => 'xid', castfunc => 'xid(xid8)',
+  castcontext => 'e', castmethod => 'f' },
+
 # OID category: allow implicit conversion from any integral type (including
 # int8, to support OID literals > 2G) to OID, as well as assignment coercion
 # from OID to int4 or int8.  Similarly for each OID-alias type.  Also allow

src/include/catalog/pg_opclass.dat

@@ -168,6 +168,10 @@
   opcintype => 'tid' },
 { opcmethod => 'hash', opcname => 'xid_ops', opcfamily => 'hash/xid_ops',
   opcintype => 'xid' },
+{ opcmethod => 'hash', opcname => 'xid8_ops', opcfamily => 'hash/xid8_ops',
+  opcintype => 'xid8' },
+{ opcmethod => 'btree', opcname => 'xid8_ops', opcfamily => 'btree/xid8_ops',
+  opcintype => 'xid8' },
 { opcmethod => 'hash', opcname => 'cid_ops', opcfamily => 'hash/cid_ops',
   opcintype => 'cid' },
 { opcmethod => 'hash', opcname => 'tid_ops', opcfamily => 'hash/tid_ops',

src/include/catalog/pg_operator.dat

@@ -193,6 +193,31 @@
   oprname => '<>', oprleft => 'xid', oprright => 'int4', oprresult => 'bool',
   oprnegate => '=(xid,int4)', oprcode => 'xidneqint4', oprrest => 'neqsel',
   oprjoin => 'neqjoinsel' },
+{ oid => '9418', descr => 'equal',
+  oprname => '=', oprcanmerge => 't', oprcanhash => 't', oprleft => 'xid8',
+  oprright => 'xid8', oprresult => 'bool', oprcom => '=(xid8,xid8)',
+  oprnegate => '<>(xid8,xid8)', oprcode => 'xid8eq', oprrest => 'eqsel',
+  oprjoin => 'eqjoinsel' },
+{ oid => '9422', descr => 'not equal',
+  oprname => '<>', oprleft => 'xid8', oprright => 'xid8',
+  oprresult => 'bool', oprcom => '<>(xid8,xid8)', oprnegate => '=(xid8,xid8)',
+  oprcode => 'xid8ne', oprrest => 'neqsel', oprjoin => 'neqjoinsel' },
+{ oid => '9432', descr => 'less than',
+  oprname => '<', oprleft => 'xid8', oprright => 'xid8', oprresult => 'bool',
+  oprcom => '>(xid8,xid8)', oprnegate => '>=(xid8,xid8)', oprcode => 'xid8lt',
+  oprrest => 'scalarltsel', oprjoin => 'scalarltjoinsel' },
+{ oid => '9433', descr => 'greater than',
+  oprname => '>', oprleft => 'xid8', oprright => 'xid8', oprresult => 'bool',
+  oprcom => '<(xid8,xid8)', oprnegate => '<=(xid8,xid8)', oprcode => 'xid8gt',
+  oprrest => 'scalargtsel', oprjoin => 'scalargtjoinsel' },
+{ oid => '9434', descr => 'less than or equal',
+  oprname => '<=', oprleft => 'xid8', oprright => 'xid8', oprresult => 'bool',
+  oprcom => '>=(xid8,xid8)', oprnegate => '>(xid8,xid8)', oprcode => 'xid8le',
+  oprrest => 'scalarlesel', oprjoin => 'scalarlejoinsel' },
+{ oid => '9435', descr => 'greater than or equal',
+  oprname => '>=', oprleft => 'xid8', oprright => 'xid8', oprresult => 'bool',
+  oprcom => '<=(xid8,xid8)', oprnegate => '<(xid8,xid8)', oprcode => 'xid8ge',
+  oprrest => 'scalargesel', oprjoin => 'scalargejoinsel' },
 { oid => '388', descr => 'factorial',
   oprname => '!', oprkind => 'r', oprleft => 'int8', oprright => '0',
   oprresult => 'numeric', oprcode => 'numeric_fac' },

src/include/catalog/pg_opfamily.dat

@@ -110,6 +110,10 @@
   opfmethod => 'btree', opfname => 'tid_ops' },
 { oid => '2225',
   opfmethod => 'hash', opfname => 'xid_ops' },
+{ oid => '8164',
+  opfmethod => 'hash', opfname => 'xid8_ops' },
+{ oid => '9322',
+  opfmethod => 'btree', opfname => 'xid8_ops' },
 { oid => '2226',
   opfmethod => 'hash', opfname => 'cid_ops' },
 { oid => '2227',

src/include/catalog/pg_proc.dat

@@ -112,6 +112,18 @@
 { oid => '51', descr => 'I/O',
   proname => 'xidout', prorettype => 'cstring', proargtypes => 'xid',
   prosrc => 'xidout' },
+{ oid => '9420', descr => 'I/O',
+  proname => 'xid8in', prorettype => 'xid8', proargtypes => 'cstring',
+  prosrc => 'xid8in' },
+{ oid => '9554', descr => 'I/O',
+  proname => 'xid8out', prorettype => 'cstring', proargtypes => 'xid8',
+  prosrc => 'xid8out' },
+{ oid => '9555', descr => 'I/O',
+  proname => 'xid8recv', prorettype => 'xid8', proargtypes => 'internal',
+  prosrc => 'xid8recv' },
+{ oid => '9556', descr => 'I/O',
+  proname => 'xid8send', prorettype => 'bytea', proargtypes => 'xid8',
+  prosrc => 'xid8send' },
 { oid => '52', descr => 'I/O',
   proname => 'cidin', prorettype => 'cid', proargtypes => 'cstring',
   prosrc => 'cidin' },
@@ -163,6 +175,30 @@
 { oid => '3308',
   proname => 'xidneq', proleakproof => 't', prorettype => 'bool',
   proargtypes => 'xid xid', prosrc => 'xidneq' },
+{ oid => '9557',
+  proname => 'xid8eq', proleakproof => 't', prorettype => 'bool',
+  proargtypes => 'xid8 xid8', prosrc => 'xid8eq' },
+{ oid => '9558',
+  proname => 'xid8ne', proleakproof => 't', prorettype => 'bool',
+  proargtypes => 'xid8 xid8', prosrc => 'xid8ne' },
+{ oid => '8295',
+  proname => 'xid8lt', proleakproof => 't', prorettype => 'bool',
+  proargtypes => 'xid8 xid8', prosrc => 'xid8lt' },
+{ oid => '8296',
+  proname => 'xid8gt', proleakproof => 't', prorettype => 'bool',
+  proargtypes => 'xid8 xid8', prosrc => 'xid8gt' },
+{ oid => '8297',
+  proname => 'xid8le', proleakproof => 't', prorettype => 'bool',
+  proargtypes => 'xid8 xid8', prosrc => 'xid8le' },
+{ oid => '8298',
+  proname => 'xid8ge', proleakproof => 't', prorettype => 'bool',
+  proargtypes => 'xid8 xid8', prosrc => 'xid8ge' },
+{ oid => '9912', descr => 'less-equal-greater',
+  proname => 'xid8cmp', proleakproof => 't', prorettype => 'int4',
+  proargtypes => 'xid8 xid8', prosrc => 'xid8cmp' },
+{ oid => '9421', descr => 'convert xid8 to xid',
+  proname => 'xid', prorettype => 'xid', proargtypes => 'xid8',
+  prosrc => 'xid8toxid' },
 { oid => '69',
   proname => 'cideq', proleakproof => 't', prorettype => 'bool',
   proargtypes => 'cid cid', prosrc => 'cideq' },

src/include/catalog/pg_type.dat

@@ -177,6 +177,10 @@
   typtype => 'p', typcategory => 'P', typinput => 'pg_ddl_command_in',
   typoutput => 'pg_ddl_command_out', typreceive => 'pg_ddl_command_recv',
   typsend => 'pg_ddl_command_send', typalign => 'ALIGNOF_POINTER' },
+{ oid => '9419', array_type_oid => '271', descr => 'full transaction id',
+  typname => 'xid8', typlen => '8', typbyval => 'FLOAT8PASSBYVAL',
+  typcategory => 'U', typinput => 'xid8in', typoutput => 'xid8out',
+  typreceive => 'xid8recv', typsend => 'xid8send', typalign => 'd' },
 
 # OIDS 600 - 699
 

src/include/utils/xid8.h

+/*-------------------------------------------------------------------------
+ *
+ * xid8.h
+ *	  Header file for the "xid8" ADT.
+ *
+ * Copyright (c) 2020, PostgreSQL Global Development Group
+ *
+ * src/include/utils/xid8.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef XID8_H
+#define XID8_H
+
+#include "access/transam.h"
+
+#define DatumGetFullTransactionId(X) (FullTransactionIdFromU64(DatumGetUInt64(X)))
+#define FullTransactionIdGetDatum(X) (UInt64GetDatum(U64FromFullTransactionId(X)))
+#define PG_GETARG_FULLTRANSACTIONID(X) DatumGetFullTransactionId(PG_GETARG_DATUM(X))
+#define PG_RETURN_FULLTRANSACTIONID(X) return FullTransactionIdGetDatum(X)
+
+#endif							/* XID8_H */

src/test/regress/expected/opr_sanity.out

@@ -832,6 +832,13 @@ macaddr8_gt(macaddr8,macaddr8)
 macaddr8_ge(macaddr8,macaddr8)
 macaddr8_ne(macaddr8,macaddr8)
 macaddr8_cmp(macaddr8,macaddr8)
+xid8lt(xid8,xid8)
+xid8gt(xid8,xid8)
+xid8le(xid8,xid8)
+xid8ge(xid8,xid8)
+xid8eq(xid8,xid8)
+xid8ne(xid8,xid8)
+xid8cmp(xid8,xid8)
 -- restore normal output mode
 \a\t
 -- List of functions used by libpq's fe-lobj.c

src/test/regress/expected/xid.out

+-- xid and xid8
+-- values in range, in octal, decimal, hex
+select '010'::xid,
+       '42'::xid,
+       '0xffffffff'::xid,
+       '-1'::xid,
+	   '010'::xid8,
+	   '42'::xid8,
+	   '0xffffffffffffffff'::xid8,
+	   '-1'::xid8;
+ xid | xid |    xid     |    xid     | xid8 | xid8 |         xid8         |         xid8         
+-----+-----+------------+------------+------+------+----------------------+----------------------
+   8 |  42 | 4294967295 | 4294967295 |    8 |   42 | 18446744073709551615 | 18446744073709551615
+(1 row)
+
+-- garbage values are not yet rejected (perhaps they should be)
+select ''::xid;
+ xid 
+-----
+   0
+(1 row)
+
+select 'asdf'::xid;
+ xid 
+-----
+   0
+(1 row)
+
+select ''::xid8;
+ xid8 
+------
+    0
+(1 row)
+
+select 'asdf'::xid8;
+ xid8 
+------
+    0
+(1 row)
+
+-- equality
+select '1'::xid = '1'::xid;
+ ?column? 
+----------
+ t
+(1 row)
+
+select '1'::xid != '1'::xid;
+ ?column? 
+----------
+ f
+(1 row)
+
+select '1'::xid8 = '1'::xid8;
+ ?column? 
+----------
+ t
+(1 row)
+
+select '1'::xid8 != '1'::xid8;
+ ?column? 
+----------
+ f
+(1 row)
+
+-- conversion
+select '1'::xid = '1'::xid8::xid;
+ ?column? 
+----------
+ t
+(1 row)
+
+select '1'::xid != '1'::xid8::xid;
+ ?column? 
+----------
+ f
+(1 row)
+
+-- we don't want relational operators for xid, due to use of modular arithmetic
+select '1'::xid < '2'::xid;
+ERROR:  operator does not exist: xid < xid
+LINE 1: select '1'::xid < '2'::xid;
+                        ^
+HINT:  No operator matches the given name and argument types. You might need to add explicit type casts.
+select '1'::xid <= '2'::xid;
+ERROR:  operator does not exist: xid <= xid
+LINE 1: select '1'::xid <= '2'::xid;
+                        ^
+HINT:  No operator matches the given name and argument types. You might need to add explicit type casts.
+select '1'::xid > '2'::xid;
+ERROR:  operator does not exist: xid > xid
+LINE 1: select '1'::xid > '2'::xid;
+                        ^
+HINT:  No operator matches the given name and argument types. You might need to add explicit type casts.
+select '1'::xid >= '2'::xid;
+ERROR:  operator does not exist: xid >= xid
+LINE 1: select '1'::xid >= '2'::xid;
+                        ^
+HINT:  No operator matches the given name and argument types. You might need to add explicit type casts.
+-- we want them for xid8 though
+select '1'::xid8 < '2'::xid8, '2'::xid8 < '2'::xid8, '2'::xid8 < '1'::xid8;
+ ?column? | ?column? | ?column? 
+----------+----------+----------
+ t        | f        | f
+(1 row)
+
+select '1'::xid8 <= '2'::xid8, '2'::xid8 <= '2'::xid8, '2'::xid8 <= '1'::xid8;
+ ?column? | ?column? | ?column? 
+----------+----------+----------
+ t        | t        | f
+(1 row)
+
+select '1'::xid8 > '2'::xid8, '2'::xid8 > '2'::xid8, '2'::xid8 > '1'::xid8;
+ ?column? | ?column? | ?column? 
+----------+----------+----------
+ f        | f        | t
+(1 row)
+
+select '1'::xid8 >= '2'::xid8, '2'::xid8 >= '2'::xid8, '2'::xid8 >= '1'::xid8;
+ ?column? | ?column? | ?column? 
+----------+----------+----------
+ f        | t        | t
+(1 row)
+
+-- we also have a 3way compare for btrees
+select xid8cmp('1', '2'), xid8cmp('2', '2'), xid8cmp('2', '1');
+ xid8cmp | xid8cmp | xid8cmp 
+---------+---------+---------
+      -1 |       0 |       1
+(1 row)
+
+-- xid8 has btree and hash opclasses
+create table xid8_t1 (x xid8);
+create index on xid8_t1 using btree(x);
+create index on xid8_t1 using hash(x);
+drop table xid8_t1;

src/test/regress/parallel_schedule

@@ -20,7 +20,7 @@ test: boolean char name varchar text int2 int4 int8 oid float4 float8 bit numeri
 # strings depends on char, varchar and text
 # numerology depends on int2, int4, int8, float4, float8
 # ----------
-test: strings numerology point lseg line box path polygon circle date time timetz timestamp timestamptz interval inet macaddr macaddr8 tstypes
+test: strings numerology point lseg line box path polygon circle date time timetz timestamp timestamptz interval inet macaddr macaddr8 tstypes xid
 
 # ----------
 # Another group of parallel tests

src/test/regress/serial_schedule

@@ -10,6 +10,7 @@ test: int2
 test: int4
 test: int8
 test: oid
+test: xid
 test: float4
 test: float8
 test: bit

src/test/regress/sql/xid.sql

+-- xid and xid8
+
+-- values in range, in octal, decimal, hex
+select '010'::xid,
+       '42'::xid,
+       '0xffffffff'::xid,
+       '-1'::xid,
+	   '010'::xid8,
+	   '42'::xid8,
+	   '0xffffffffffffffff'::xid8,
+	   '-1'::xid8;
+
+-- garbage values are not yet rejected (perhaps they should be)
+select ''::xid;
+select 'asdf'::xid;
+select ''::xid8;
+select 'asdf'::xid8;
+
+-- equality
+select '1'::xid = '1'::xid;
+select '1'::xid != '1'::xid;
+select '1'::xid8 = '1'::xid8;
+select '1'::xid8 != '1'::xid8;
+
+-- conversion
+select '1'::xid = '1'::xid8::xid;
+select '1'::xid != '1'::xid8::xid;
+
+-- we don't want relational operators for xid, due to use of modular arithmetic
+select '1'::xid < '2'::xid;
+select '1'::xid <= '2'::xid;
+select '1'::xid > '2'::xid;
+select '1'::xid >= '2'::xid;
+
+-- we want them for xid8 though
+select '1'::xid8 < '2'::xid8, '2'::xid8 < '2'::xid8, '2'::xid8 < '1'::xid8;
+select '1'::xid8 <= '2'::xid8, '2'::xid8 <= '2'::xid8, '2'::xid8 <= '1'::xid8;
+select '1'::xid8 > '2'::xid8, '2'::xid8 > '2'::xid8, '2'::xid8 > '1'::xid8;
+select '1'::xid8 >= '2'::xid8, '2'::xid8 >= '2'::xid8, '2'::xid8 >= '1'::xid8;
+
+-- we also have a 3way compare for btrees
+select xid8cmp('1', '2'), xid8cmp('2', '2'), xid8cmp('2', '1');
+
+-- xid8 has btree and hash opclasses
+create table xid8_t1 (x xid8);
+create index on xid8_t1 using btree(x);
+create index on xid8_t1 using hash(x);
+drop table xid8_t1;