Hi hackers,
Unlike xid, xid8 increases monotonically and cannot be reused.
This trait makes it possible to support min() and max() aggregate
functions for xid8.
I thought they would be useful for monitoring.
So I made a patch for this.
Best wishes,
--
Ken Kato
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 8754f2f89b..1b064b4feb 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -19973,7 +19973,7 @@ SELECT NULLIF(value, '(none)') ...
values. Available for any numeric, string, date/time, or enum type,
as well as <type>inet</type>, <type>interval</type>,
<type>money</type>, <type>oid</type>, <type>pg_lsn</type>,
- <type>tid</type>,
+ <type>tid</type>, <type>xid8</type>,
and arrays of any of these types.
</para></entry>
<entry>Yes</entry>
@@ -19992,7 +19992,7 @@ SELECT NULLIF(value, '(none)') ...
values. Available for any numeric, string, date/time, or enum type,
as well as <type>inet</type>, <type>interval</type>,
<type>money</type>, <type>oid</type>, <type>pg_lsn</type>,
- <type>tid</type>,
+ <type>tid</type>, <type>xid8</type>,
and arrays of any of these types.
</para></entry>
<entry>Yes</entry>
diff --git a/src/backend/utils/adt/xid.c b/src/backend/utils/adt/xid.c
index 9b4ceaea47..6e24697782 100644
--- a/src/backend/utils/adt/xid.c
+++ b/src/backend/utils/adt/xid.c
@@ -286,6 +286,24 @@ xid8cmp(PG_FUNCTION_ARGS)
PG_RETURN_INT32(-1);
}
+Datum
+xid8_larger(PG_FUNCTION_ARGS)
+{
+ FullTransactionId fxid1 = PG_GETARG_FULLTRANSACTIONID(0);
+ FullTransactionId fxid2 = PG_GETARG_FULLTRANSACTIONID(1);
+
+ PG_RETURN_FULLTRANSACTIONID((U64FromFullTransactionId(fxid1) > U64FromFullTransactionId(fxid2)) ? fxid1 : fxid2);
+}
+
+Datum
+xid8_smaller(PG_FUNCTION_ARGS)
+{
+ FullTransactionId fxid1 = PG_GETARG_FULLTRANSACTIONID(0);
+ FullTransactionId fxid2 = PG_GETARG_FULLTRANSACTIONID(1);
+
+ PG_RETURN_FULLTRANSACTIONID((U64FromFullTransactionId(fxid1) < U64FromFullTransactionId(fxid2)) ? fxid1 : fxid2);
+}
+
/*****************************************************************************
* COMMAND IDENTIFIER ROUTINES *
*****************************************************************************/
diff --git a/src/include/catalog/pg_aggregate.dat b/src/include/catalog/pg_aggregate.dat
index 137f6eef69..2843f4b415 100644
--- a/src/include/catalog/pg_aggregate.dat
+++ b/src/include/catalog/pg_aggregate.dat
@@ -149,6 +149,9 @@
{ aggfnoid => 'max(pg_lsn)', aggtransfn => 'pg_lsn_larger',
aggcombinefn => 'pg_lsn_larger', aggsortop => '>(pg_lsn,pg_lsn)',
aggtranstype => 'pg_lsn' },
+{ aggfnoid => 'max(xid8)', aggtransfn => 'xid8_larger',
+ aggcombinefn => 'xid8_larger', aggsortop => '>(xid8,xid8)',
+ aggtranstype => 'xid8' },
# min
{ aggfnoid => 'min(int8)', aggtransfn => 'int8smaller',
@@ -214,6 +217,9 @@
{ aggfnoid => 'min(pg_lsn)', aggtransfn => 'pg_lsn_smaller',
aggcombinefn => 'pg_lsn_smaller', aggsortop => '<(pg_lsn,pg_lsn)',
aggtranstype => 'pg_lsn' },
+{ aggfnoid => 'min(xid8)', aggtransfn => 'xid8_smaller',
+ aggcombinefn => 'xid8_smaller', aggsortop => '<(xid8,xid8)',
+ aggtranstype => 'xid8' },
# count
{ aggfnoid => 'count(any)', aggtransfn => 'int8inc_any',
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 7024dbe10a..62f36daa98 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -203,6 +203,12 @@
{ oid => '5071', descr => 'convert xid8 to xid',
proname => 'xid', prorettype => 'xid', proargtypes => 'xid8',
prosrc => 'xid8toxid' },
+{ oid => '5097', descr => 'larger of two',
+ proname => 'xid8_larger', prorettype => 'xid8', proargtypes => 'xid8 xid8',
+ prosrc => 'xid8_larger' },
+{ oid => '5098', descr => 'smaller of two',
+ proname => 'xid8_smaller', prorettype => 'xid8', proargtypes => 'xid8 xid8',
+ prosrc => 'xid8_smaller' },
{ oid => '69',
proname => 'cideq', proleakproof => 't', prorettype => 'bool',
proargtypes => 'cid cid', prosrc => 'cideq' },
@@ -6564,6 +6570,9 @@
{ oid => '4189', descr => 'maximum value of all pg_lsn input values',
proname => 'max', prokind => 'a', proisstrict => 'f', prorettype => 'pg_lsn',
proargtypes => 'pg_lsn', prosrc => 'aggregate_dummy' },
+{ oid => '5099', descr => 'maximum value of all xid8 input values',
+ proname => 'max', prokind => 'a', proisstrict => 'f', prorettype => 'xid8',
+ proargtypes => 'xid8', prosrc => 'aggregate_dummy' },
{ oid => '2131', descr => 'minimum value of all bigint input values',
proname => 'min', prokind => 'a', proisstrict => 'f', prorettype => 'int8',
@@ -6631,6 +6640,9 @@
{ oid => '4190', descr => 'minimum value of all pg_lsn input values',
proname => 'min', prokind => 'a', proisstrict => 'f', prorettype => 'pg_lsn',
proargtypes => 'pg_lsn', prosrc => 'aggregate_dummy' },
+{ oid => '5100', descr => 'minimum value of all xid8 input values',
+ proname => 'min', prokind => 'a', proisstrict => 'f', prorettype => 'xid8',
+ proargtypes => 'xid8', prosrc => 'aggregate_dummy' },
# count has two forms: count(any) and count(*)
{ oid => '2147',
