diff --git a/include/my_time.h b/include/my_time.h
index 08fef1b5c6d9a..87e42318e4966 100644
--- a/include/my_time.h
+++ b/include/my_time.h
@@ -301,6 +301,47 @@ enum interval_type
   INTERVAL_MINUTE_MICROSECOND, INTERVAL_SECOND_MICROSECOND, INTERVAL_LAST
 };
 
+/**
+  High-precision timestamp representation.
+
+  Stores a UNIX timestamp as a seconds-since-epoch value and a sub-second
+  part in microseconds.
+*/
+typedef struct my_timespec
+{
+  my_time_t sec;
+  ulong usec;
+} my_timespec_t;
+
+static inline
+int cmp(my_timespec_t a, my_timespec_t b)
+{
+  return ((a.sec > b.sec || (a.sec == b.sec && a.usec > b.usec)) ? 1 :
+         ((a.sec < b.sec || (a.sec == b.sec && a.usec < b.usec)) ? -1 : 0));
+}
+
 C_MODE_END
 
+#ifdef __cplusplus
+constexpr my_timespec_t MY_TIMESPEC_MIN= {MY_TIME_T_MIN, 0};
+constexpr my_timespec_t MY_TIMESPEC_MAX= {TIMESTAMP_MAX_VALUE, TIME_MAX_SECOND_PART};
+
+inline
+bool operator< (my_timespec_t a, my_timespec_t b)
+{
+  return cmp(a, b) < 0;
+}
+
+inline
+bool operator> (my_timespec_t a, my_timespec_t b)
+{
+  return cmp(a, b) > 0;
+}
+
+inline
+bool operator== (my_timespec_t a, my_timespec_t b)
+{
+  return (a.sec == b.sec) && (a.usec == b.usec);
+}
+#endif
 #endif /* _my_time_h_ */
diff --git a/mysql-test/main/partition.result b/mysql-test/main/partition.result
index 48cc686c6567c..e7fc0e6855a55 100644
--- a/mysql-test/main/partition.result
+++ b/mysql-test/main/partition.result
@@ -2922,4 +2922,19 @@ DROP TABLE mdev20498;
 #
 # End of 10.6 tests
 #
+#
+# MDEV-25529 ALTER TABLE FORCE syntax improved
+#
+create table t1 (id int primary key);
+alter table t1 force partition by hash(id) partitions 2;
+alter table t1 force remove partitioning;
+alter table t1 partition by hash(id) partitions 2 force;
+alter table t1 remove partitioning force;
+alter table t1 force partition by hash(id) partitions 2 force;
+ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'force' at line 1
+alter table t1 force remove partitioning force;
+ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'force' at line 1
+alter table t1 add column x int partition by hash(id) partitions 2;
+alter table t1 remove partitioning add column y int;
+drop table t1;
 ALTER DATABASE test CHARACTER SET utf8mb4 COLLATE utf8mb4_uca1400_ai_ci;
diff --git a/mysql-test/main/partition.test b/mysql-test/main/partition.test
index 4f6ec51659cff..6703d5bdb4313 100644
--- a/mysql-test/main/partition.test
+++ b/mysql-test/main/partition.test
@@ -3147,4 +3147,21 @@ DROP TABLE mdev20498;
 --echo # End of 10.6 tests
 --echo #
 
+--echo #
+--echo # MDEV-25529 ALTER TABLE FORCE syntax improved
+--echo #
+create table t1 (id int primary key);
+alter table t1 force partition by hash(id) partitions 2;
+alter table t1 force remove partitioning;
+alter table t1 partition by hash(id) partitions 2 force;
+alter table t1 remove partitioning force;
+--error ER_PARSE_ERROR
+alter table t1 force partition by hash(id) partitions 2 force;
+--error ER_PARSE_ERROR
+alter table t1 force remove partitioning force;
+# Strange syntax, but it exists since 2005 (cd483c55)
+alter table t1 add column x int partition by hash(id) partitions 2;
+alter table t1 remove partitioning add column y int;
+drop table t1;
+
 --source include/test_db_charset_restore.inc
diff --git a/mysql-test/suite/versioning/r/partition.result b/mysql-test/suite/versioning/r/partition.result
index c2a09cf7794a8..70677bde7e14e 100644
--- a/mysql-test/suite/versioning/r/partition.result
+++ b/mysql-test/suite/versioning/r/partition.result
@@ -472,7 +472,7 @@ PARTITIONS 2
 create or replace table t1 (i int) with system versioning
 partition by system_time interval 1 day starts '2000-01-01 00:00:01';
 Warnings:
-Warning	4164	`t1`: STARTS is later than query time, first history partition may exceed INTERVAL value
+Warning	4164	`t1`: STARTS timestamp 2000-01-01 00:00:01 is later than query timestamp 2000-01-01 00:00:00, first history partition may exceed INTERVAL value
 # Test default STARTS rounding
 set timestamp= unix_timestamp('1999-12-15 13:33:33');
 create or replace table t1 (i int) with system versioning
@@ -544,7 +544,7 @@ set time_zone="+03:00";
 create or replace table t1 (i int) with system versioning
 partition by system_time interval 1 day starts '2000-01-01 00:00:00';
 Warnings:
-Warning	4164	`t1`: STARTS is later than query time, first history partition may exceed INTERVAL value
+Warning	4164	`t1`: STARTS timestamp 2000-01-01 00:00:00 is later than query timestamp 1999-12-15 16:33:33, first history partition may exceed INTERVAL value
 set timestamp= unix_timestamp('2000-01-01 00:00:00');
 create or replace table t2 (i int) with system versioning
 partition by system_time interval 1 day;
@@ -604,7 +604,7 @@ create or replace table t1 (i int) with system versioning
 partition by system_time interval 1 day starts '2000-01-03 00:00:00'
 partitions 3;
 Warnings:
-Warning	4164	`t1`: STARTS is later than query time, first history partition may exceed INTERVAL value
+Warning	4164	`t1`: STARTS timestamp 2000-01-03 00:00:00 is later than query timestamp 2000-01-01 00:00:00, first history partition may exceed INTERVAL value
 insert into t1 values (0);
 set timestamp= unix_timestamp('2000-01-01 00:00:01');
 update t1 set i= i + 1;
diff --git a/mysql-test/suite/versioning/r/partition2.result b/mysql-test/suite/versioning/r/partition2.result
new file mode 100644
index 0000000000000..378365da702c6
--- /dev/null
+++ b/mysql-test/suite/versioning/r/partition2.result
@@ -0,0 +1,530 @@
+set @@session.time_zone='+00:00';
+#
+# MDEV-25529 Auto-create: Pre-existing historical data is not partitioned as specified by ALTER
+#
+create or replace table t1 (x int) with system versioning
+partition by system_time limit 1;
+alter table t1 partition by system_time limit 1 auto;
+create or replace table t1 (x int,
+row_start timestamp(6) as row start invisible,
+row_end timestamp(6) as row end invisible,
+period for system_time (row_start, row_end),
+index (row_end, row_start),
+index (row_start),
+index (row_end, x),
+index (x, row_end),
+index (row_end desc)) with system versioning
+partition by system_time limit 1000 partitions 6;
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `x` int(11) DEFAULT NULL,
+  `row_start` timestamp(6) GENERATED ALWAYS AS ROW START INVISIBLE,
+  `row_end` timestamp(6) GENERATED ALWAYS AS ROW END INVISIBLE,
+  KEY `row_end` (`row_end`,`row_start`),
+  KEY `row_start` (`row_start`),
+  KEY `row_end_2` (`row_end`,`x`),
+  KEY `x` (`x`,`row_end`),
+  KEY `row_end_3` (`row_end` DESC),
+  PERIOD FOR SYSTEM_TIME (`row_start`, `row_end`)
+) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci WITH SYSTEM VERSIONING
+ PARTITION BY SYSTEM_TIME LIMIT 1000
+PARTITIONS 6
+set timestamp= unix_timestamp('2000-01-01 00:00:00');
+insert t1 values (0);
+set timestamp= unix_timestamp('2000-01-01 00:10:00.22');
+update t1 set x= x + 1;
+set timestamp= unix_timestamp('2000-01-01 01:00:00');
+update t1 set x= x + 1;
+set timestamp= unix_timestamp('2000-01-01 01:30:00');
+update t1 set x= x + 1;
+set timestamp= unix_timestamp('2000-01-01 02:00:00');
+update t1 set x= x + 1;
+select *, row_start, row_end from t1 partition (p0);
+x	row_start	row_end
+0	2000-01-01 00:00:00.000000	2000-01-01 00:10:00.220000
+1	2000-01-01 00:10:00.220000	2000-01-01 01:00:00.000000
+2	2000-01-01 01:00:00.000000	2000-01-01 01:30:00.000000
+3	2000-01-01 01:30:00.000000	2000-01-01 02:00:00.000000
+select *, row_start, row_end from t1 partition (p1);
+x	row_start	row_end
+select *, row_start, row_end from t1 partition (p2);
+x	row_start	row_end
+select *, row_start, row_end from t1 partition (p3);
+x	row_start	row_end
+select *, row_start, row_end from t1 partition (p4);
+x	row_start	row_end
+select *, row_start, row_end from t1 partition (pn);
+x	row_start	row_end
+4	2000-01-01 02:00:00.000000	2106-02-07 06:28:15.999999
+set timestamp= default;
+ALTER table t1 partition by system_time
+interval 1 hour starts '2000-01-01 00:00:00';
+select *, row_start, row_end from t1 partition (p0);
+x	row_start	row_end
+0	2000-01-01 00:00:00.000000	2000-01-01 00:10:00.220000
+select *, row_start, row_end from t1 partition (p1);
+x	row_start	row_end
+1	2000-01-01 00:10:00.220000	2000-01-01 01:00:00.000000
+2	2000-01-01 01:00:00.000000	2000-01-01 01:30:00.000000
+select *, row_start, row_end from t1 partition (p2);
+x	row_start	row_end
+3	2000-01-01 01:30:00.000000	2000-01-01 02:00:00.000000
+select *, row_start, row_end from t1 partition (p3);
+x	row_start	row_end
+select *, row_start, row_end from t1 partition (p4);
+x	row_start	row_end
+select *, row_start, row_end from t1 partition (pn);
+x	row_start	row_end
+4	2000-01-01 02:00:00.000000	2106-02-07 06:28:15.999999
+alter TABLE t1 partition by system_time
+interval 1 hour;
+select *, row_start, row_end from t1 partition (p0);
+x	row_start	row_end
+0	2000-01-01 00:00:00.000000	2000-01-01 00:10:00.220000
+select *, row_start, row_end from t1 partition (p1);
+x	row_start	row_end
+1	2000-01-01 00:10:00.220000	2000-01-01 01:00:00.000000
+2	2000-01-01 01:00:00.000000	2000-01-01 01:30:00.000000
+select *, row_start, row_end from t1 partition (p2);
+x	row_start	row_end
+3	2000-01-01 01:30:00.000000	2000-01-01 02:00:00.000000
+select *, row_start, row_end from t1 partition (p3);
+x	row_start	row_end
+select *, row_start, row_end from t1 partition (p4);
+x	row_start	row_end
+select *, row_start, row_end from t1 partition (pn);
+x	row_start	row_end
+4	2000-01-01 02:00:00.000000	2106-02-07 06:28:15.999999
+set @@system_versioning_alter_history= keep;
+alter table t1 remove partitioning;
+select *, row_start, row_end from t1 for system_time all;
+x	row_start	row_end
+0	2000-01-01 00:00:00.000000	2000-01-01 00:10:00.220000
+1	2000-01-01 00:10:00.220000	2000-01-01 01:00:00.000000
+2	2000-01-01 01:00:00.000000	2000-01-01 01:30:00.000000
+3	2000-01-01 01:30:00.000000	2000-01-01 02:00:00.000000
+4	2000-01-01 02:00:00.000000	2106-02-07 06:28:15.999999
+alter table t1 PARTITION by system_time interval 1 hour auto;
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `x` int(11) DEFAULT NULL,
+  `row_start` timestamp(6) GENERATED ALWAYS AS ROW START INVISIBLE,
+  `row_end` timestamp(6) GENERATED ALWAYS AS ROW END INVISIBLE,
+  KEY `row_end` (`row_end`,`row_start`),
+  KEY `row_start` (`row_start`),
+  KEY `row_end_2` (`row_end`,`x`),
+  KEY `x` (`x`,`row_end`),
+  KEY `row_end_3` (`row_end` DESC),
+  PERIOD FOR SYSTEM_TIME (`row_start`, `row_end`)
+) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci WITH SYSTEM VERSIONING
+ PARTITION BY SYSTEM_TIME INTERVAL 1 HOUR STARTS TIMESTAMP'2000-01-01 00:00:00' AUTO
+PARTITIONS 3
+select *, row_start, row_end from t1 partition (p0);
+x	row_start	row_end
+0	2000-01-01 00:00:00.000000	2000-01-01 00:10:00.220000
+select *, row_start, row_end from t1 partition (p1);
+x	row_start	row_end
+1	2000-01-01 00:10:00.220000	2000-01-01 01:00:00.000000
+2	2000-01-01 01:00:00.000000	2000-01-01 01:30:00.000000
+3	2000-01-01 01:30:00.000000	2000-01-01 02:00:00.000000
+select *, row_start, row_end from t1 partition (pn);
+x	row_start	row_end
+4	2000-01-01 02:00:00.000000	2106-02-07 06:28:15.999999
+alter table t1 remove partitioning;
+alter table t1 partition by SYSTEM_TIME interval 1 hour starts '2000-01-01 00:00:00' auto;
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `x` int(11) DEFAULT NULL,
+  `row_start` timestamp(6) GENERATED ALWAYS AS ROW START INVISIBLE,
+  `row_end` timestamp(6) GENERATED ALWAYS AS ROW END INVISIBLE,
+  KEY `row_end` (`row_end`,`row_start`),
+  KEY `row_start` (`row_start`),
+  KEY `row_end_2` (`row_end`,`x`),
+  KEY `x` (`x`,`row_end`),
+  KEY `row_end_3` (`row_end` DESC),
+  PERIOD FOR SYSTEM_TIME (`row_start`, `row_end`)
+) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci WITH SYSTEM VERSIONING
+ PARTITION BY SYSTEM_TIME INTERVAL 1 HOUR STARTS TIMESTAMP'2000-01-01 00:00:00' AUTO
+PARTITIONS 3
+select *, row_start, row_end from t1 partition (p0);
+x	row_start	row_end
+0	2000-01-01 00:00:00.000000	2000-01-01 00:10:00.220000
+select *, row_start, row_end from t1 partition (p1);
+x	row_start	row_end
+1	2000-01-01 00:10:00.220000	2000-01-01 01:00:00.000000
+2	2000-01-01 01:00:00.000000	2000-01-01 01:30:00.000000
+3	2000-01-01 01:30:00.000000	2000-01-01 02:00:00.000000
+select *, row_start, row_end from t1 partition (pn);
+x	row_start	row_end
+4	2000-01-01 02:00:00.000000	2106-02-07 06:28:15.999999
+set timestamp= unix_timestamp('2000-01-02 03:01:23.456');
+delete from t1;
+alter table t1 remove partitioning;
+alter table t1 partition by SYSTEM_TIME interval 1 hour auto;
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `x` int(11) DEFAULT NULL,
+  `row_start` timestamp(6) GENERATED ALWAYS AS ROW START INVISIBLE,
+  `row_end` timestamp(6) GENERATED ALWAYS AS ROW END INVISIBLE,
+  KEY `row_end` (`row_end`,`row_start`),
+  KEY `row_start` (`row_start`),
+  KEY `row_end_2` (`row_end`,`x`),
+  KEY `x` (`x`,`row_end`),
+  KEY `row_end_3` (`row_end` DESC),
+  PERIOD FOR SYSTEM_TIME (`row_start`, `row_end`)
+) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci WITH SYSTEM VERSIONING
+ PARTITION BY SYSTEM_TIME INTERVAL 1 HOUR STARTS TIMESTAMP'2000-01-01 00:00:00' AUTO
+PARTITIONS 29
+select *, row_start, row_end from t1 partition (p0);
+x	row_start	row_end
+0	2000-01-01 00:00:00.000000	2000-01-01 00:10:00.220000
+select *, row_start, row_end from t1 partition (p1);
+x	row_start	row_end
+1	2000-01-01 00:10:00.220000	2000-01-01 01:00:00.000000
+2	2000-01-01 01:00:00.000000	2000-01-01 01:30:00.000000
+select *, row_start, row_end from t1 partition (p2);
+x	row_start	row_end
+3	2000-01-01 01:30:00.000000	2000-01-01 02:00:00.000000
+select *, row_start, row_end from t1 partition (p27);
+x	row_start	row_end
+4	2000-01-01 02:00:00.000000	2000-01-02 03:01:23.456000
+select *, row_start, row_end from t1 partition (pn);
+x	row_start	row_end
+set timestamp= unix_timestamp('2000-01-02 03:01:23.456');
+delete from t1;
+alter table t1 partition by system_time INTERVAL 20 minute auto force;
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `x` int(11) DEFAULT NULL,
+  `row_start` timestamp(6) GENERATED ALWAYS AS ROW START INVISIBLE,
+  `row_end` timestamp(6) GENERATED ALWAYS AS ROW END INVISIBLE,
+  KEY `row_end` (`row_end`,`row_start`),
+  KEY `row_start` (`row_start`),
+  KEY `row_end_2` (`row_end`,`x`),
+  KEY `x` (`x`,`row_end`),
+  KEY `row_end_3` (`row_end` DESC),
+  PERIOD FOR SYSTEM_TIME (`row_start`, `row_end`)
+) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci WITH SYSTEM VERSIONING
+ PARTITION BY SYSTEM_TIME INTERVAL 20 MINUTE STARTS TIMESTAMP'2000-01-01 00:10:00' AUTO
+PARTITIONS 82
+select *, row_start, row_end from t1 partition (p0);
+x	row_start	row_end
+0	2000-01-01 00:00:00.000000	2000-01-01 00:10:00.220000
+select *, row_start, row_end from t1 partition (p2);
+x	row_start	row_end
+1	2000-01-01 00:10:00.220000	2000-01-01 01:00:00.000000
+select *, row_start, row_end from t1 partition (p5);
+x	row_start	row_end
+3	2000-01-01 01:30:00.000000	2000-01-01 02:00:00.000000
+select *, row_start, row_end from t1 partition (pn);
+x	row_start	row_end
+alter table t1 remove partitioning;
+alter table t1 partition by system_time interval 1 hour
+starts '2002-01-01 00:00:00' auto;
+Warnings:
+Warning	4164	`t1`: STARTS timestamp 2002-01-01 00:00:00 is later than query timestamp 2000-01-02 03:01:23, first history partition may exceed INTERVAL value
+Warning	4265	`t1`: STARTS timestamp 2002-01-01 00:00:00 is above earliest history date 2000-01-01 00:10:00 and was set to 2000-01-01 00:00:00
+# STARTS changed and WARN_VERS_WRONG_STARTS is here
+alter table t1 force partition by system_time interval 1 hour
+starts '2003-01-01 00:00:00' auto;
+Warnings:
+Warning	4265	`t1`: STARTS timestamp 2003-01-01 00:00:00 is above earliest history date 2000-01-01 00:10:00 and was set to 2000-01-01 00:00:00
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `x` int(11) DEFAULT NULL,
+  `row_start` timestamp(6) GENERATED ALWAYS AS ROW START INVISIBLE,
+  `row_end` timestamp(6) GENERATED ALWAYS AS ROW END INVISIBLE,
+  KEY `row_end` (`row_end`,`row_start`),
+  KEY `row_start` (`row_start`),
+  KEY `row_end_2` (`row_end`,`x`),
+  KEY `x` (`x`,`row_end`),
+  KEY `row_end_3` (`row_end` DESC),
+  PERIOD FOR SYSTEM_TIME (`row_start`, `row_end`)
+) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci WITH SYSTEM VERSIONING
+ PARTITION BY SYSTEM_TIME INTERVAL 1 HOUR STARTS TIMESTAMP'2000-01-01 00:00:00' AUTO
+PARTITIONS 29
+alter table t1 partition by system_time interval 1 hour
+starts '2004-01-01 00:00:00' auto force;
+Warnings:
+Warning	4164	`t1`: STARTS timestamp 2004-01-01 00:00:00 is later than query timestamp 2000-01-02 03:01:23, first history partition may exceed INTERVAL value
+Warning	4265	`t1`: STARTS timestamp 2004-01-01 00:00:00 is above earliest history date 2000-01-01 00:10:00 and was set to 2000-01-01 00:00:00
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `x` int(11) DEFAULT NULL,
+  `row_start` timestamp(6) GENERATED ALWAYS AS ROW START INVISIBLE,
+  `row_end` timestamp(6) GENERATED ALWAYS AS ROW END INVISIBLE,
+  KEY `row_end` (`row_end`,`row_start`),
+  KEY `row_start` (`row_start`),
+  KEY `row_end_2` (`row_end`,`x`),
+  KEY `x` (`x`,`row_end`),
+  KEY `row_end_3` (`row_end` DESC),
+  PERIOD FOR SYSTEM_TIME (`row_start`, `row_end`)
+) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci WITH SYSTEM VERSIONING
+ PARTITION BY SYSTEM_TIME INTERVAL 1 HOUR STARTS TIMESTAMP'2000-01-01 00:00:00' AUTO
+PARTITIONS 29
+# STARTS doesn't change without FORCE
+alter table t1 partition by system_time interval 1 hour
+starts '2005-01-01 00:00:00' auto;
+Warnings:
+Warning	4164	`t1`: STARTS timestamp 2005-01-01 00:00:00 is later than query timestamp 2000-01-02 03:01:23, first history partition may exceed INTERVAL value
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `x` int(11) DEFAULT NULL,
+  `row_start` timestamp(6) GENERATED ALWAYS AS ROW START INVISIBLE,
+  `row_end` timestamp(6) GENERATED ALWAYS AS ROW END INVISIBLE,
+  KEY `row_end` (`row_end`,`row_start`),
+  KEY `row_start` (`row_start`),
+  KEY `row_end_2` (`row_end`,`x`),
+  KEY `x` (`x`,`row_end`),
+  KEY `row_end_3` (`row_end` DESC),
+  PERIOD FOR SYSTEM_TIME (`row_start`, `row_end`)
+) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci WITH SYSTEM VERSIONING
+ PARTITION BY SYSTEM_TIME INTERVAL 1 HOUR STARTS TIMESTAMP'2005-01-01 00:00:00' AUTO
+PARTITIONS 29
+# min_ts == max_ts case, partitions decrease
+delete history from t1;
+set timestamp= unix_timestamp('2000-01-01 00:00:00');
+insert t1 values (77);
+delete from t1;
+alter table t1 partition by system_time interval 7 hour auto force;
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `x` int(11) DEFAULT NULL,
+  `row_start` timestamp(6) GENERATED ALWAYS AS ROW START INVISIBLE,
+  `row_end` timestamp(6) GENERATED ALWAYS AS ROW END INVISIBLE,
+  KEY `row_end` (`row_end`,`row_start`),
+  KEY `row_start` (`row_start`),
+  KEY `row_end_2` (`row_end`,`x`),
+  KEY `x` (`x`,`row_end`),
+  KEY `row_end_3` (`row_end` DESC),
+  PERIOD FOR SYSTEM_TIME (`row_start`, `row_end`)
+) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci WITH SYSTEM VERSIONING
+ PARTITION BY SYSTEM_TIME INTERVAL 7 HOUR STARTS TIMESTAMP'2000-01-01 00:00:00' AUTO
+PARTITIONS 2
+# Explicit partition list ignores AUTO FORCE
+set timestamp= unix_timestamp('2000-01-03 00:00:00');
+insert t1 values (88);
+delete from t1;
+alter table t1 partition by system_time interval 8 hour auto force;
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `x` int(11) DEFAULT NULL,
+  `row_start` timestamp(6) GENERATED ALWAYS AS ROW START INVISIBLE,
+  `row_end` timestamp(6) GENERATED ALWAYS AS ROW END INVISIBLE,
+  KEY `row_end` (`row_end`,`row_start`),
+  KEY `row_start` (`row_start`),
+  KEY `row_end_2` (`row_end`,`x`),
+  KEY `x` (`x`,`row_end`),
+  KEY `row_end_3` (`row_end` DESC),
+  PERIOD FOR SYSTEM_TIME (`row_start`, `row_end`)
+) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci WITH SYSTEM VERSIONING
+ PARTITION BY SYSTEM_TIME INTERVAL 8 HOUR STARTS TIMESTAMP'2000-01-01 00:00:00' AUTO
+PARTITIONS 7
+alter table t1 partition by system_time interval 8 hour auto (
+partition p0 history,
+partition p1 history,
+partition pn current) force;
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `x` int(11) DEFAULT NULL,
+  `row_start` timestamp(6) GENERATED ALWAYS AS ROW START INVISIBLE,
+  `row_end` timestamp(6) GENERATED ALWAYS AS ROW END INVISIBLE,
+  KEY `row_end` (`row_end`,`row_start`),
+  KEY `row_start` (`row_start`),
+  KEY `row_end_2` (`row_end`,`x`),
+  KEY `x` (`x`,`row_end`),
+  KEY `row_end_3` (`row_end` DESC),
+  PERIOD FOR SYSTEM_TIME (`row_start`, `row_end`)
+) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci WITH SYSTEM VERSIONING
+ PARTITION BY SYSTEM_TIME INTERVAL 8 HOUR STARTS TIMESTAMP'2000-01-03 00:00:00' AUTO
+(PARTITION `p0` HISTORY ENGINE = MyISAM,
+ PARTITION `p1` HISTORY ENGINE = MyISAM,
+ PARTITION `pn` CURRENT ENGINE = MyISAM)
+# Switch system_time -> hash
+alter table t1 partition by hash(x) partitions 3;
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `x` int(11) DEFAULT NULL,
+  `row_start` timestamp(6) GENERATED ALWAYS AS ROW START INVISIBLE,
+  `row_end` timestamp(6) GENERATED ALWAYS AS ROW END INVISIBLE,
+  KEY `row_end` (`row_end`,`row_start`),
+  KEY `row_start` (`row_start`),
+  KEY `row_end_2` (`row_end`,`x`),
+  KEY `x` (`x`,`row_end`),
+  KEY `row_end_3` (`row_end` DESC),
+  PERIOD FOR SYSTEM_TIME (`row_start`, `row_end`)
+) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci WITH SYSTEM VERSIONING
+ PARTITION BY HASH (`x`)
+PARTITIONS 3
+# Switch hash -> system_time
+alter table t1 partition by system_time interval 9 hour
+starts '2001-01-01 00:00:00' auto force;
+Warnings:
+Warning	4164	`t1`: STARTS timestamp 2001-01-01 00:00:00 is later than query timestamp 2000-01-03 00:00:00, first history partition may exceed INTERVAL value
+Warning	4265	`t1`: STARTS timestamp 2001-01-01 00:00:00 is above earliest history date 2000-01-01 00:00:00 and was set to 2000-01-01 00:00:00
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `x` int(11) DEFAULT NULL,
+  `row_start` timestamp(6) GENERATED ALWAYS AS ROW START INVISIBLE,
+  `row_end` timestamp(6) GENERATED ALWAYS AS ROW END INVISIBLE,
+  KEY `row_end` (`row_end`,`row_start`),
+  KEY `row_start` (`row_start`),
+  KEY `row_end_2` (`row_end`,`x`),
+  KEY `x` (`x`,`row_end`),
+  KEY `row_end_3` (`row_end` DESC),
+  PERIOD FOR SYSTEM_TIME (`row_start`, `row_end`)
+) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci WITH SYSTEM VERSIONING
+ PARTITION BY SYSTEM_TIME INTERVAL 9 HOUR STARTS TIMESTAMP'2000-01-01 00:00:00' AUTO
+PARTITIONS 7
+# Year/month interval
+delete history from t1;
+alter table t1 remove partitioning;
+set timestamp= unix_timestamp('2000-01-01 00:00:00');
+insert t1 values (77);
+delete from t1;
+alter table t1 partition by system_time interval 1 month auto force;
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `x` int(11) DEFAULT NULL,
+  `row_start` timestamp(6) GENERATED ALWAYS AS ROW START INVISIBLE,
+  `row_end` timestamp(6) GENERATED ALWAYS AS ROW END INVISIBLE,
+  KEY `row_end` (`row_end`,`row_start`),
+  KEY `row_start` (`row_start`),
+  KEY `row_end_2` (`row_end`,`x`),
+  KEY `x` (`x`,`row_end`),
+  KEY `row_end_3` (`row_end` DESC),
+  PERIOD FOR SYSTEM_TIME (`row_start`, `row_end`)
+) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci WITH SYSTEM VERSIONING
+ PARTITION BY SYSTEM_TIME INTERVAL 1 MONTH STARTS TIMESTAMP'2000-01-01 00:00:00' AUTO
+PARTITIONS 2
+set timestamp= unix_timestamp('2003-10-01 00:00:00');
+insert t1 values (88);
+delete from t1;
+alter table t1 partition by system_time interval 11 month auto force;
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `x` int(11) DEFAULT NULL,
+  `row_start` timestamp(6) GENERATED ALWAYS AS ROW START INVISIBLE,
+  `row_end` timestamp(6) GENERATED ALWAYS AS ROW END INVISIBLE,
+  KEY `row_end` (`row_end`,`row_start`),
+  KEY `row_start` (`row_start`),
+  KEY `row_end_2` (`row_end`,`x`),
+  KEY `x` (`x`,`row_end`),
+  KEY `row_end_3` (`row_end` DESC),
+  PERIOD FOR SYSTEM_TIME (`row_start`, `row_end`)
+) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci WITH SYSTEM VERSIONING
+ PARTITION BY SYSTEM_TIME INTERVAL 11 MONTH STARTS TIMESTAMP'2000-01-01 00:00:00' AUTO
+PARTITIONS 6
+alter table t1 partition by system_time interval 1 year auto force;
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `x` int(11) DEFAULT NULL,
+  `row_start` timestamp(6) GENERATED ALWAYS AS ROW START INVISIBLE,
+  `row_end` timestamp(6) GENERATED ALWAYS AS ROW END INVISIBLE,
+  KEY `row_end` (`row_end`,`row_start`),
+  KEY `row_start` (`row_start`),
+  KEY `row_end_2` (`row_end`,`x`),
+  KEY `x` (`x`,`row_end`),
+  KEY `row_end_3` (`row_end` DESC),
+  PERIOD FOR SYSTEM_TIME (`row_start`, `row_end`)
+) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci WITH SYSTEM VERSIONING
+ PARTITION BY SYSTEM_TIME INTERVAL 1 YEAR STARTS TIMESTAMP'2000-01-01 00:00:00' AUTO
+PARTITIONS 5
+# No history
+delete history from t1;
+set timestamp= unix_timestamp('2000-01-01 00:00:00');
+alter table t1 partition by system_time interval 1 hour auto force;
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `x` int(11) DEFAULT NULL,
+  `row_start` timestamp(6) GENERATED ALWAYS AS ROW START INVISIBLE,
+  `row_end` timestamp(6) GENERATED ALWAYS AS ROW END INVISIBLE,
+  KEY `row_end` (`row_end`,`row_start`),
+  KEY `row_start` (`row_start`),
+  KEY `row_end_2` (`row_end`,`x`),
+  KEY `x` (`x`,`row_end`),
+  KEY `row_end_3` (`row_end` DESC),
+  PERIOD FOR SYSTEM_TIME (`row_start`, `row_end`)
+) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci WITH SYSTEM VERSIONING
+ PARTITION BY SYSTEM_TIME INTERVAL 1 HOUR STARTS TIMESTAMP'2000-01-01 00:00:00' AUTO
+PARTITIONS 5
+insert t1 values (99);
+alter table t1 partition by system_time interval 1 hour auto force;
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `x` int(11) DEFAULT NULL,
+  `row_start` timestamp(6) GENERATED ALWAYS AS ROW START INVISIBLE,
+  `row_end` timestamp(6) GENERATED ALWAYS AS ROW END INVISIBLE,
+  KEY `row_end` (`row_end`,`row_start`),
+  KEY `row_start` (`row_start`),
+  KEY `row_end_2` (`row_end`,`x`),
+  KEY `x` (`x`,`row_end`),
+  KEY `row_end_3` (`row_end` DESC),
+  PERIOD FOR SYSTEM_TIME (`row_start`, `row_end`)
+) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci WITH SYSTEM VERSIONING
+ PARTITION BY SYSTEM_TIME INTERVAL 1 HOUR STARTS TIMESTAMP'2000-01-01 00:00:00' AUTO
+PARTITIONS 5
+# Slow scan warning
+create or replace table t1 (x int,
+row_start timestamp(6) as row start invisible,
+row_end timestamp(6) as row end invisible,
+period for system_time (row_start, row_end),
+index (x, row_end, row_start),
+index (row_start, row_end),
+index (x, row_end)) with system versioning;
+set timestamp= unix_timestamp('2000-01-01 00:00:00');
+insert t1 values (77);
+delete from t1;
+set timestamp= unix_timestamp('2000-01-03 00:00:00');
+insert t1 values (88);
+delete from t1;
+alter table t1 partition by system_time interval 10 hour auto;
+Warnings:
+Warning	4266	`t1`: ROW END index not found, using slow scan
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `x` int(11) DEFAULT NULL,
+  `row_start` timestamp(6) GENERATED ALWAYS AS ROW START INVISIBLE,
+  `row_end` timestamp(6) GENERATED ALWAYS AS ROW END INVISIBLE,
+  KEY `x` (`x`,`row_end`,`row_start`),
+  KEY `row_start` (`row_start`,`row_end`),
+  KEY `x_2` (`x`,`row_end`),
+  PERIOD FOR SYSTEM_TIME (`row_start`, `row_end`)
+) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci WITH SYSTEM VERSIONING
+ PARTITION BY SYSTEM_TIME INTERVAL 10 HOUR STARTS TIMESTAMP'2000-01-01 00:00:00' AUTO
+PARTITIONS 6
+# TRX_ID versioning
+create or replace table t1 (x int,
+row_start bigint(20) unsigned as row start invisible,
+row_end bigint(20) unsigned as row end invisible,
+period for system_time (row_start, row_end),
+index (row_end)) with system versioning engine innodb;
+set timestamp= unix_timestamp('2000-01-01 00:00:00');
+insert t1 values (77);
+delete from t1;
+set timestamp= unix_timestamp('2000-01-03 00:00:00');
+insert t1 values (88);
+delete from t1;
+# Partitioning is not allowed for TRX_ID versioning
+alter table t1 partition by system_time interval 11 hour auto;
+ERROR HY000: `row_start` must be of type TIMESTAMP(6) for system-versioned table `t1`
+drop table t1;
diff --git a/mysql-test/suite/versioning/t/partition2.test b/mysql-test/suite/versioning/t/partition2.test
new file mode 100644
index 0000000000000..5c07790084b23
--- /dev/null
+++ b/mysql-test/suite/versioning/t/partition2.test
@@ -0,0 +1,230 @@
+--source include/have_partition.inc
+--source include/have_innodb.inc
+--source include/maybe_debug.inc
+
+--enable_prepare_warnings
+set @@session.time_zone='+00:00';
+
+--echo #
+--echo # MDEV-25529 Auto-create: Pre-existing historical data is not partitioned as specified by ALTER
+--echo #
+
+# Test both index and scan, compare the results between them
+if ($have_debug)
+{
+  --disable_query_log
+  set @old_dbug= @@debug_dbug;
+  set debug_dbug= '+d,test_mdev-25529';
+  --enable_query_log
+}
+
+create or replace table t1 (x int) with system versioning
+partition by system_time limit 1;
+alter table t1 partition by system_time limit 1 auto;
+
+create or replace table t1 (x int,
+  row_start timestamp(6) as row start invisible,
+  row_end timestamp(6) as row end invisible,
+  period for system_time (row_start, row_end),
+  index (row_end, row_start),
+  index (row_start),
+  index (row_end, x),
+  index (x, row_end),
+  index (row_end desc)) with system versioning
+partition by system_time limit 1000 partitions 6;
+
+show create table t1;
+set timestamp= unix_timestamp('2000-01-01 00:00:00');
+insert t1 values (0);
+set timestamp= unix_timestamp('2000-01-01 00:10:00.22');
+update t1 set x= x + 1;
+set timestamp= unix_timestamp('2000-01-01 01:00:00');
+update t1 set x= x + 1;
+set timestamp= unix_timestamp('2000-01-01 01:30:00');
+update t1 set x= x + 1;
+set timestamp= unix_timestamp('2000-01-01 02:00:00');
+update t1 set x= x + 1;
+
+select *, row_start, row_end from t1 partition (p0);
+select *, row_start, row_end from t1 partition (p1);
+select *, row_start, row_end from t1 partition (p2);
+select *, row_start, row_end from t1 partition (p3);
+select *, row_start, row_end from t1 partition (p4);
+select *, row_start, row_end from t1 partition (pn);
+set timestamp= default;
+
+ALTER table t1 partition by system_time
+interval 1 hour starts '2000-01-01 00:00:00';
+select *, row_start, row_end from t1 partition (p0);
+select *, row_start, row_end from t1 partition (p1);
+select *, row_start, row_end from t1 partition (p2);
+select *, row_start, row_end from t1 partition (p3);
+select *, row_start, row_end from t1 partition (p4);
+select *, row_start, row_end from t1 partition (pn);
+
+alter TABLE t1 partition by system_time
+interval 1 hour;
+select *, row_start, row_end from t1 partition (p0);
+select *, row_start, row_end from t1 partition (p1);
+select *, row_start, row_end from t1 partition (p2);
+select *, row_start, row_end from t1 partition (p3);
+select *, row_start, row_end from t1 partition (p4);
+select *, row_start, row_end from t1 partition (pn);
+
+set @@system_versioning_alter_history= keep;
+alter table t1 remove partitioning;
+# First history:  2000-01-01 00:10:00.220000
+# Last history:   2000-01-01 02:00:00.00000021
+select *, row_start, row_end from t1 for system_time all;
+
+alter table t1 PARTITION by system_time interval 1 hour auto;
+
+show create table t1;
+select *, row_start, row_end from t1 partition (p0);
+select *, row_start, row_end from t1 partition (p1);
+select *, row_start, row_end from t1 partition (pn);
+
+alter table t1 remove partitioning;
+alter table t1 partition by SYSTEM_TIME interval 1 hour starts '2000-01-01 00:00:00' auto;
+
+show create table t1;
+select *, row_start, row_end from t1 partition (p0);
+select *, row_start, row_end from t1 partition (p1);
+select *, row_start, row_end from t1 partition (pn);
+
+set timestamp= unix_timestamp('2000-01-02 03:01:23.456');
+delete from t1;
+alter table t1 remove partitioning;
+alter table t1 partition by SYSTEM_TIME interval 1 hour auto;
+
+show create table t1;
+select *, row_start, row_end from t1 partition (p0);
+select *, row_start, row_end from t1 partition (p1);
+select *, row_start, row_end from t1 partition (p2);
+select *, row_start, row_end from t1 partition (p27);
+select *, row_start, row_end from t1 partition (pn);
+
+set timestamp= unix_timestamp('2000-01-02 03:01:23.456');
+delete from t1;
+alter table t1 partition by system_time INTERVAL 20 minute auto force;
+show create table t1;
+select *, row_start, row_end from t1 partition (p0);
+select *, row_start, row_end from t1 partition (p2);
+select *, row_start, row_end from t1 partition (p5);
+select *, row_start, row_end from t1 partition (pn);
+
+alter table t1 remove partitioning;
+alter table t1 partition by system_time interval 1 hour
+starts '2002-01-01 00:00:00' auto;
+
+--echo # STARTS changed and WARN_VERS_WRONG_STARTS is here
+alter table t1 force partition by system_time interval 1 hour
+starts '2003-01-01 00:00:00' auto;
+show create table t1;
+
+alter table t1 partition by system_time interval 1 hour
+starts '2004-01-01 00:00:00' auto force;
+show create table t1;
+
+--echo # STARTS doesn't change without FORCE
+alter table t1 partition by system_time interval 1 hour
+starts '2005-01-01 00:00:00' auto;
+show create table t1;
+
+--echo # min_ts == max_ts case, partitions decrease
+delete history from t1;
+set timestamp= unix_timestamp('2000-01-01 00:00:00');
+insert t1 values (77);
+delete from t1;
+alter table t1 partition by system_time interval 7 hour auto force;
+show create table t1;
+
+--echo # Explicit partition list ignores AUTO FORCE
+set timestamp= unix_timestamp('2000-01-03 00:00:00');
+insert t1 values (88);
+delete from t1;
+alter table t1 partition by system_time interval 8 hour auto force;
+show create table t1;
+
+alter table t1 partition by system_time interval 8 hour auto (
+  partition p0 history,
+  partition p1 history,
+  partition pn current) force;
+show create table t1;
+
+--echo # Switch system_time -> hash
+alter table t1 partition by hash(x) partitions 3;
+show create table t1;
+--echo # Switch hash -> system_time
+alter table t1 partition by system_time interval 9 hour
+starts '2001-01-01 00:00:00' auto force;
+show create table t1;
+
+--echo # Year/month interval
+delete history from t1;
+alter table t1 remove partitioning;
+set timestamp= unix_timestamp('2000-01-01 00:00:00');
+insert t1 values (77);
+delete from t1;
+alter table t1 partition by system_time interval 1 month auto force;
+show create table t1;
+set timestamp= unix_timestamp('2003-10-01 00:00:00');
+insert t1 values (88);
+delete from t1;
+alter table t1 partition by system_time interval 11 month auto force;
+show create table t1;
+alter table t1 partition by system_time interval 1 year auto force;
+show create table t1;
+
+--echo # No history
+delete history from t1;
+set timestamp= unix_timestamp('2000-01-01 00:00:00');
+alter table t1 partition by system_time interval 1 hour auto force;
+show create table t1;
+insert t1 values (99);
+alter table t1 partition by system_time interval 1 hour auto force;
+show create table t1;
+
+--echo # Slow scan warning
+create or replace table t1 (x int,
+  row_start timestamp(6) as row start invisible,
+  row_end timestamp(6) as row end invisible,
+  period for system_time (row_start, row_end),
+  index (x, row_end, row_start),
+  index (row_start, row_end),
+  index (x, row_end)) with system versioning;
+set timestamp= unix_timestamp('2000-01-01 00:00:00');
+insert t1 values (77);
+delete from t1;
+set timestamp= unix_timestamp('2000-01-03 00:00:00');
+insert t1 values (88);
+delete from t1;
+alter table t1 partition by system_time interval 10 hour auto;
+show create table t1;
+
+--echo # TRX_ID versioning
+create or replace table t1 (x int,
+  row_start bigint(20) unsigned as row start invisible,
+  row_end bigint(20) unsigned as row end invisible,
+  period for system_time (row_start, row_end),
+  index (row_end)) with system versioning engine innodb;
+set timestamp= unix_timestamp('2000-01-01 00:00:00');
+insert t1 values (77);
+delete from t1;
+set timestamp= unix_timestamp('2000-01-03 00:00:00');
+insert t1 values (88);
+delete from t1;
+--echo # Partitioning is not allowed for TRX_ID versioning
+--error ER_VERS_FIELD_WRONG_TYPE
+alter table t1 partition by system_time interval 11 hour auto;
+
+drop table t1;
+
+if ($have_debug)
+{
+  --disable_query_log
+  set debug_dbug= @old_dbug;
+  --enable_query_log
+}
+
+--disable_prepare_warnings
diff --git a/sql/event_data_objects.cc b/sql/event_data_objects.cc
index 72bc2d38d0779..3a1b01156d8e6 100644
--- a/sql/event_data_objects.cc
+++ b/sql/event_data_objects.cc
@@ -689,6 +689,10 @@ add_interval(MYSQL_TIME *ltime, const Time_zone *time_zone,
 /*
   Computes the sum of a timestamp plus interval.
 
+  Computes the smallest next > time_now obtained by adding one or more
+  multiples of the given interval (i_value, i_type) to start, taking
+  into account time_zone conversions and DST ambiguities.
+
   SYNOPSIS
     get_next_time()
       time_zone     event time zone
diff --git a/sql/field.cc b/sql/field.cc
index aa20a08be45b1..b390d5a7fde48 100644
--- a/sql/field.cc
+++ b/sql/field.cc
@@ -2406,6 +2406,59 @@ bool Field_vers_trx_id::get_date(MYSQL_TIME *ltime, date_mode_t fuzzydate, ulong
 }
 
 
+/**
+  Retrieve the UNIX timestamp for a transaction-versioned field value.
+
+  Reads the transaction ID from the raw field storage at @p pos and looks
+  it up in the transaction registry table (TRT). If the stored value equals
+  @c ULONGLONG_MAX (the open-ended "infinity" sentinel), returns
+  @c TIMESTAMP_MAX_VALUE immediately without a TRT lookup.
+
+  If the transaction ID is not found in the TRT, emits @c ER_VERS_NO_TRX_ID
+  as a warning and returns @c -1.
+
+  @note  A missing TRT entry is reported as a warning rather than a fatal
+         error because the registry row may have been purged after the
+         versioned row was written; the caller can still continue.
+
+  @param[in]  pos       Pointer to the raw 8-byte field value containing
+                        the transaction ID.
+  @param[out] sec_part  If non-NULL, receives the microsecond part of the
+                        commit timestamp.
+
+  @return  Commit timestamp in seconds since epoch, @c TIMESTAMP_MAX_VALUE
+           for the infinity sentinel, or @c -1 if the transaction ID is not
+           found in the TRT.
+*/
+my_time_t Field_vers_trx_id::get_timestamp(const uchar *pos, ulong *sec_part) const
+{
+  ulonglong trx_id= uint8korr(pos);
+  THD *thd= get_thd();
+  if (trx_id == ULONGLONG_MAX)
+  {
+    if (sec_part)
+    {
+      *sec_part= TIME_MAX_SECOND_PART;
+    }
+    return TIMESTAMP_MAX_VALUE;
+  }
+  TR_table trt(thd);
+  if (trt.query(trx_id))
+  {
+    return trt[TR_table::FLD_COMMIT_TS]->get_timestamp(sec_part);
+  }
+
+  if (sec_part)
+    *sec_part= 0;
+
+  push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN,
+                      ER_VERS_NO_TRX_ID, ER_THD(thd, ER_VERS_NO_TRX_ID),
+                      (longlong) trx_id);
+
+  return -1;
+}
+
+
 Field_str::Field_str(uchar *ptr_arg,uint32 len_arg, uchar *null_ptr_arg,
                      uchar null_bit_arg, utype unireg_check_arg,
                      const LEX_CSTRING *field_name_arg,
diff --git a/sql/field.h b/sql/field.h
index a509c194bb101..0e8bb0bd598e0 100644
--- a/sql/field.h
+++ b/sql/field.h
@@ -3003,6 +3003,7 @@ class Field_vers_trx_id :public Field_longlong {
   {
     return get_date(ltime, fuzzydate, (ulonglong) val_int());
   }
+  my_time_t get_timestamp(const uchar *pos, ulong *sec_part) const override;
   bool test_if_equality_guarantees_uniqueness(const Item *item) const override;
   Data_type_compatibility can_optimize_keypart_ref(const Item_bool_func *,
                                                    const Item *)
diff --git a/sql/partition_info.cc b/sql/partition_info.cc
index a55a0840bf220..43c66ee677355 100644
--- a/sql/partition_info.cc
+++ b/sql/partition_info.cc
@@ -429,6 +429,7 @@ bool partition_info::set_up_default_partitions(THD *thd, handler *file,
   i= 0;
   do
   {
+    // TODO (newbie): how is it freed? Explain in comment or remake via table->mem_root.
     partition_element *part_elem= new partition_element();
     if (likely(part_elem != 0 && !partitions.push_back(part_elem)))
     {
@@ -448,7 +449,10 @@ bool partition_info::set_up_default_partitions(THD *thd, handler *file,
       }
     }
     else
+    {
+      my_error(ER_OUT_OF_RESOURCES, MYF(0));
       goto end;
+    }
   } while (++i < num_parts);
   result= FALSE;
 end:
@@ -2824,6 +2828,7 @@ bool partition_info::vers_set_interval(THD* thd, Item* interval,
   /* 2. assign STARTS to interval.start */
   if (starts)
   {
+    vers_info->starts_clause= true;
     if (starts->fix_fields_if_needed_for_scalar(thd, &starts))
       return true;
     switch (starts->result_type())
@@ -2852,30 +2857,21 @@ bool partition_info::vers_set_interval(THD* thd, Item* interval,
     }
     if (!table)
     {
-      if (thd->query_start() < vers_info->interval.start) {
+      if (thd->query_start() < vers_info->interval.start &&
+          !(auto_hist && (thd->lex->alter_info.flags & ALTER_RECREATE)))
+      {
+        TimestampString str_interval(thd, vers_info->interval.start);
+        TimestampString str_query(thd, thd->query_start());
         push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN,
-                            ER_PART_STARTS_BEYOND_INTERVAL,
-                            ER_THD(thd, ER_PART_STARTS_BEYOND_INTERVAL),
-                            table_name);
+                            WARN_VERS_STARTS_BEYOND_INTERVAL,
+                            ER_THD(thd, WARN_VERS_STARTS_BEYOND_INTERVAL),
+                            table_name, str_interval.cstr(), str_query.cstr());
       }
     }
   }
   else // calculate default STARTS depending on INTERVAL
   {
-    thd->variables.time_zone->gmt_sec_to_TIME(&ltime, thd->query_start());
-    if (vers_info->interval.step.second)
-      goto interval_set_starts;
-    ltime.second= 0;
-    if (vers_info->interval.step.minute)
-      goto interval_set_starts;
-    ltime.minute= 0;
-    if (vers_info->interval.step.hour)
-      goto interval_set_starts;
-    ltime.hour= 0;
-
-interval_set_starts:
-    vers_info->interval.start= TIME_to_timestamp(thd, &ltime, &err);
-    if (err)
+    if (vers_set_starts(thd, thd->query_start()))
       goto interval_starts_error;
   }
 
@@ -2887,6 +2883,41 @@ bool partition_info::vers_set_interval(THD* thd, Item* interval,
 }
 
 
+/**
+  Round down the STARTS value to the partition interval boundary.
+
+  Converts @p ts to broken-down local time in the current session time zone,
+  then clears time components (second, minute, hour) until the value aligns
+  with the coarsest unit present in @c vers_info->interval.step. The
+  result is stored back in @c vers_info->interval.start.
+
+  @param thd  Current thread.
+  @param ts   Timestamp to align.
+
+  @retval false  Success.
+  @retval true   Error while converting the rounded value back to TIMESTAMP.
+*/
+bool partition_info::vers_set_starts(THD *thd, my_time_t ts)
+{
+  MYSQL_TIME ltime;
+  uint err;
+  thd->variables.time_zone->gmt_sec_to_TIME(&ltime, ts);
+  if (vers_info->interval.step.second)
+    goto interval_set_starts;
+  ltime.second= 0;
+  if (vers_info->interval.step.minute)
+    goto interval_set_starts;
+  ltime.minute= 0;
+  if (vers_info->interval.step.hour)
+    goto interval_set_starts;
+  ltime.hour= 0;
+
+interval_set_starts:
+  vers_info->interval.start= TIME_to_timestamp(thd, &ltime, &err);
+  return (bool) err;
+}
+
+
 bool partition_info::vers_set_limit(ulonglong limit, bool auto_hist,
                                     const char *table_name)
 {
diff --git a/sql/partition_info.h b/sql/partition_info.h
index e25e27860c966..6debf10189f2d 100644
--- a/sql/partition_info.h
+++ b/sql/partition_info.h
@@ -37,6 +37,7 @@ struct Vers_part_info : public Sql_alloc
   Vers_part_info() :
     limit(0),
     auto_hist(false),
+    starts_clause(false),
     now_part(NULL),
     hist_part(NULL)
   {
@@ -46,6 +47,7 @@ struct Vers_part_info : public Sql_alloc
     interval(src.interval),
     limit(src.limit),
     auto_hist(src.auto_hist),
+    starts_clause(src.starts_clause),
     now_part(NULL),
     hist_part(NULL)
   {
@@ -55,6 +57,7 @@ struct Vers_part_info : public Sql_alloc
     interval= src.interval;
     limit= src.limit;
     auto_hist= src.auto_hist;
+    starts_clause= src.starts_clause;
     now_part= src.now_part;
     hist_part= src.hist_part;
     return *this;
@@ -87,6 +90,7 @@ struct Vers_part_info : public Sql_alloc
   } interval;
   ulonglong limit;
   bool auto_hist;
+  bool starts_clause;
   partition_element *now_part;
   partition_element *hist_part;
 };
@@ -420,6 +424,7 @@ class partition_info : public DDL_LOG_STATE, public Sql_alloc
   bool vers_set_interval(THD *thd, Item *interval,
                          interval_type int_type, Item *starts,
                          bool auto_part, const char *table_name);
+  bool vers_set_starts(THD *thd, my_time_t ts);
   bool vers_set_limit(ulonglong limit, bool auto_part, const char *table_name);
   bool vers_set_hist_part(THD* thd, uint *create_count);
   bool vers_require_hist_part(THD *thd) const
diff --git a/sql/share/errmsg-utf8.txt b/sql/share/errmsg-utf8.txt
index 611ca88b2d130..92d03b8bb8211 100644
--- a/sql/share/errmsg-utf8.txt
+++ b/sql/share/errmsg-utf8.txt
@@ -12144,10 +12144,10 @@ ER_UNKNOWN_OPERATOR
         sw "Opereta haipo: '%-.128s'"
 ER_SP_DUP_DECL
 	eng "Duplicate declaration: '%-.64s'"
-ER_PART_STARTS_BEYOND_INTERVAL
-        eng "%sQ: STARTS is later than query time, first history partition may exceed INTERVAL value"
-        spa "%sQ: STARTS es posterior al momento de consulta (query), la primera partición de historia puede exceder el valor INTERVAL"
-        sw "%sQ: STARTS ni ya baadaye kuliko muda wa hoja, kizigeu cha kwanza ya historia inaweza kuzidi thamani ya INTERVAL"
+WARN_VERS_STARTS_BEYOND_INTERVAL
+        eng "%sQ: STARTS timestamp %s is later than query timestamp %s, first history partition may exceed INTERVAL value"
+        spa "%sQ: STARTS %s es posterior al momento de consulta (query) %s, la primera partición de historia puede exceder el valor INTERVAL"
+        sw "%sQ: STARTS %s ni wa baadaye kuliko muda wa hoja %s, kizigeu cha kwanza cha historia kinaweza kuzidi thamani ya INTERVAL"
 ER_GALERA_REPLICATION_NOT_SUPPORTED
         eng "Galera replication not supported"
         spa "La replicación en Galera no está soportada"
@@ -12406,3 +12406,11 @@ ER_WARN_QB_NAME_PATH_VIEW_NOT_FOUND
         eng "Hint %s is ignored. `%s` required at element #%u of the path is not found in the target query block."
 ER_WARN_QB_NAME_PATH_NOT_SUPPORTED_INSIDE_VIEW
         eng "Hint %s is ignored. QB_NAME hints with path are not supported inside view definitions."
+WARN_VERS_WRONG_STARTS
+        chi "%sQ: STARTS 时间戳 %s 晚于最早历史日期 %s，已被设置为 %s"
+        eng "%sQ: STARTS timestamp %s is above earliest history date %s and was set to %s"
+        spa "%sQ: la marca de tiempo STARTS %s es posterior a la fecha histórica más temprana %s y se estableció en %s"
+WARN_VERS_SLOW_ROW_END
+        chi "%sQ: 未找到 ROW END 索引，正在使用慢速扫描"
+        eng "%sQ: ROW END index not found, using slow scan"
+        spa "%sQ: no se encontró el índice ROW END, usando escaneo lento"
diff --git a/sql/sql_class.cc b/sql/sql_class.cc
index 70c571f14e6ec..7f92bb246140c 100644
--- a/sql/sql_class.cc
+++ b/sql/sql_class.cc
@@ -9126,6 +9126,28 @@ bool THD::timestamp_to_TIME(MYSQL_TIME *ltime, my_time_t ts,
 }
 
 
+/**
+  Format a timestamp as a string using the session time zone.
+
+  Converts @p ts to a Temporal_hybrid value in the current session time zone
+  and stores its string representation with @p dec fractional second digits
+  in @p str. Sets the @c TIME_ZONE_USED flag on the current statement.
+
+  @param str  Destination string.
+  @param dec  Number of fractional second digits (0-6).
+  @param ts   Timestamp value to format.
+
+  @retval false  Success.
+  @retval true   Conversion or formatting error.
+*/
+bool THD::timestamp_to_string(String *str, uint dec, my_timespec_t ts)
+{
+  Temporal_hybrid th(this, ts);
+  used|= TIME_ZONE_USED;
+  return th.to_string(str, dec) == nullptr;
+}
+
+
 void THD::my_ok_with_recreate_info(const Recreate_info &info,
                                    ulong warn_count)
 {
diff --git a/sql/sql_class.h b/sql/sql_class.h
index aad3defa963be..3392fe68a6405 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -4780,6 +4780,11 @@ class THD: public THD_count, /* this must be first */
   const Type_handler *type_handler_for_datetime() const;
   bool timestamp_to_TIME(MYSQL_TIME *ltime, my_time_t ts,
                          ulong sec_part, date_mode_t fuzzydate);
+  bool timestamp_to_string(String *str, uint dec, my_timespec_t ts);
+  bool timestamp_to_string(String *str, uint dec, my_time_t ts)
+  {
+    return timestamp_to_string(str, dec, {ts, 0});
+  }
   inline my_time_t query_start() { return start_time; }
   inline ulong query_start_sec_part()
   { used|= QUERY_START_SEC_PART_USED; return start_time_sec_part; }
@@ -8721,6 +8726,45 @@ class Write_log_with_flags
 };
 
 
+class TimestampString : public String
+{
+  THD *thd;
+  my_timespec_t ts;
+
+public:
+  /**
+    Construct a lazily formatted timestamp from a high-precision value.
+
+    @param thd  Current thread.
+    @param ts   Timestamp value (seconds + microseconds) to format on demand.
+  */
+  TimestampString(THD *thd, my_timespec_t ts) : thd{thd}, ts{ts} {}
+  /**
+    Construct a lazily formatted timestamp from a whole-seconds value.
+
+    @param thd  Current thread.
+    @param sec  Timestamp in seconds since epoch.
+  */
+  TimestampString(THD *thd, my_time_t sec) : thd{thd}, ts{sec, 0} {}
+
+  /**
+    Return the timestamp formatted as a null-terminated C string.
+
+    Formats the stored timestamp into this String object on demand.
+
+    @param dec  Number of fractional second digits to include (default 0).
+
+    @return  Pointer to the formatted string, or @c "ERROR" on failure.
+  */
+  const char * cstr(uint dec= 0)
+  {
+    if (thd->timestamp_to_string(this, dec, ts))
+      return "ERROR";
+    else
+      return c_ptr_safe();
+  }
+};
+
 /**
   Make a new string allocated on THD's mem-root.
 
diff --git a/sql/sql_partition.cc b/sql/sql_partition.cc
index e997b596cbc58..72bbfaab3caed 100644
--- a/sql/sql_partition.cc
+++ b/sql/sql_partition.cc
@@ -100,6 +100,29 @@ static int get_partition_id_linear_key_sub(partition_info *part_info, uint32 *pa
 static uint32 get_next_partition_via_walking(PARTITION_ITERATOR*);
 static void set_up_range_analysis_info(partition_info *part_info);
 static uint32 get_next_subpartition_via_walking(PARTITION_ITERATOR*);
+/**
+  Calculate the number of history partitions required for a time range.
+
+  Uses @c interval.start as the left boundary and @p end as the right
+  boundary. For second-based intervals the count is computed arithmetically
+  using interval2sec(). For month- or year-based intervals, boundaries are
+  advanced step by step using date_add_interval() in the current session
+  time zone.
+
+  @param thd         Current thread.
+  @param end         Right boundary (inclusive) of the history range as a
+                     UNIX timestamp.
+  @param interval    Partition interval definition.
+  @param hist_parts  Out parameter receiving the number of history partitions
+                     needed.
+
+  @retval false  Success.
+  @retval true   Error: interval overflow or number of partitions would
+                 exceed @c MAX_PARTITIONS.
+*/
+static bool vers_calc_hist_parts(THD *thd, my_time_t end,
+                                 const Vers_part_info::interval_t &interval,
+                                 uint *hist_parts);
 #endif
 
 uint32 get_next_partition_id_range(PARTITION_ITERATOR* part_iter);
@@ -6138,6 +6161,70 @@ the generated partition syntax in a correct manner.
         }
       }
 
+      if (table->versioned() &&
+          (alter_info->partition_flags & ALTER_PARTITION_INFO) &&
+          part_info->part_type == VERSIONING_PARTITION &&
+          part_info->vers_info->auto_hist &&
+          alt_part_info->use_default_partitions &&
+          (!*fast_alter_table || (alter_info->flags & ALTER_RECREATE)))
+      {
+        if (*fast_alter_table)
+          *fast_alter_table= false;
+        my_timespec_t min_ts, max_ts;
+        Vers_part_info *vers_info= part_info->vers_info;
+        auto &interval= vers_info->interval;
+        if (table->vers_get_history_range(thd, min_ts, max_ts))
+          DBUG_RETURN(true);
+        if (max_ts.sec > MY_TIME_T_MIN) /* there is history in the table */
+        {
+          DBUG_ASSERT(max_ts.sec < TIMESTAMP_MAX_VALUE);
+          DBUG_ASSERT(min_ts.sec <= max_ts.sec);
+          if (max_ts.usec)
+          {
+            max_ts.sec++;
+            max_ts.usec= 0;
+          }
+          if (vers_info->starts_clause)
+          {
+            if (interval.start > min_ts.sec)
+            {
+              TimestampString str_interval(thd, interval.start);
+              if (part_info->vers_set_starts(thd, min_ts.sec))
+              {
+                my_error(ER_PART_WRONG_VALUE, MYF(0),
+                         table->s->table_name.str, "STARTS");
+                DBUG_RETURN(true);
+              }
+              TimestampString str_min_ts(thd, min_ts);
+              TimestampString str_interval2(thd, interval.start);
+              push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN,
+                                  WARN_VERS_WRONG_STARTS, ER_THD(thd, WARN_VERS_WRONG_STARTS),
+                                  table->s->table_name.str,
+                                  str_interval.cstr(), str_min_ts.cstr(), str_interval2.cstr());
+
+            }
+          }
+          else if (part_info->vers_set_starts(thd, min_ts.sec))
+          {
+            my_error(ER_PART_WRONG_VALUE, MYF(0),
+                     table->s->table_name.str, "STARTS");
+            DBUG_RETURN(true);
+          }
+
+          part_info->use_default_num_partitions= false;
+          part_info->use_default_partitions= true;
+          part_info->default_partitions_setup= false;
+          part_info->partitions.empty();
+
+          uint hist_parts= 0;
+          if (vers_calc_hist_parts(thd, max_ts.sec, interval, &hist_parts))
+            DBUG_RETURN(true);
+          part_info->num_parts= hist_parts + 1;
+        } /* if (max_ts.sec > MY_TIME_T_MIN) */
+        else
+          DBUG_ASSERT(max_ts == MY_TIMESPEC_MIN); /* no history in table */
+      } /* if (need to get history range) */
+
       /*
         Set up partition default_engine_type either from the create_info
         or from the previus table
@@ -6163,7 +6250,7 @@ the generated partition syntax in a correct manner.
         DBUG_ASSERT(create_info->db_type);
         create_info->db_type= partition_hton;
       }
-    }
+    } /* if (thd->work_part_info) */
   }
   DBUG_RETURN(FALSE);
 err:
@@ -6174,6 +6261,71 @@ the generated partition syntax in a correct manner.
 }
 
 
+static bool vers_calc_hist_parts(THD *thd, my_time_t end,
+                                 const Vers_part_info::interval_t &interval,
+                                 uint *hist_parts)
+{
+  uint error= 0;
+  my_time_t start= interval.start;
+  DBUG_ASSERT(hist_parts != NULL);
+  *hist_parts= 0;
+
+  if (end < start)
+    return false;
+
+  if (end == start)
+  {
+    *hist_parts= 1;
+    return false;
+  }
+
+  if (!(interval.step.year || interval.step.month))
+  {
+    my_time_t range= end - start;
+    const longlong i_sec= interval2sec(&interval.step);
+    DBUG_ASSERT(i_sec > 0);
+
+    *hist_parts= static_cast<uint>(range / i_sec);
+    if ((*hist_parts) * i_sec != range)
+      (*hist_parts)++;
+    if (*hist_parts >= MAX_PARTITIONS)
+    {
+      my_error(ER_TOO_MANY_PARTITIONS_ERROR, MYF(0));
+      return true;
+    }
+    return false;
+  }
+
+  MYSQL_TIME boundary;
+  thd->variables.time_zone->gmt_sec_to_TIME(&boundary, start);
+
+  while (start < end)
+  {
+    if (date_add_interval(thd, &boundary, interval.type, interval.step))
+    {
+      my_error(ER_DATA_OUT_OF_RANGE, MYF(0), "TIMESTAMP", "INTERVAL");
+      return true;
+    }
+
+    start= thd->variables.time_zone->TIME_to_gmt_sec(&boundary, &error);
+    if (error)
+    {
+      my_error(ER_DATA_OUT_OF_RANGE, MYF(0), "TIMESTAMP", "INTERVAL");
+      return true;
+    }
+
+    (*hist_parts)++;
+    if (*hist_parts >= MAX_PARTITIONS)
+    {
+      my_error(ER_TOO_MANY_PARTITIONS_ERROR, MYF(0));
+      return true;
+    }
+  }
+
+  return false;
+}
+
+
 /*
   Change partitions, used to implement ALTER TABLE ADD/REORGANIZE/COALESCE
   partitions. This method is used to implement both single-phase and multi-
diff --git a/sql/sql_table.cc b/sql/sql_table.cc
index 4d2c1d6861647..1f9cc0b95a32f 100644
--- a/sql/sql_table.cc
+++ b/sql/sql_table.cc
@@ -64,6 +64,7 @@
 #include "rpl_rli.h"
 #include "log.h"
 #include "vector_mhnsw.h"
+#include "key.h"
 
 #ifdef WITH_WSREP
 #include "wsrep_mysqld.h"
@@ -2488,7 +2489,7 @@ void promote_first_timestamp_column(List<Create_field> *column_definitions)
   }
 }
 
-static bool key_cmp(const Key_part_spec &a, const Key_part_spec &b)
+static bool key_eq(const Key_part_spec &a, const Key_part_spec &b)
 {
   return a.length == b.length && a.asc == b.asc &&
          a.field_name.streq(b.field_name);
@@ -2532,7 +2533,7 @@ static void check_duplicate_key(THD *thd, const Key *key, const KEY *key_info,
     }
 
     if (std::equal(key->columns.begin(), key->columns.end(), k.columns.begin(),
-                   key_cmp))
+                   key_eq))
     {
       push_warning_printf(thd, Sql_condition::WARN_LEVEL_NOTE, ER_DUP_INDEX,
                           ER_THD(thd, ER_DUP_INDEX), key_info->name.str);
@@ -13936,3 +13937,171 @@ bool HA_CREATE_INFO::
   }
   return false;
 }
+
+
+#ifdef WITH_PARTITION_STORAGE_ENGINE
+/**
+  Find the minimum and maximum historical row-end timestamps in a versioned
+  table.
+
+  Selects the shortest forward index that starts with the row-end field and
+  reads its first and last entries to obtain the range. If no suitable
+  index exists, falls back to a full table scan with a warning. Open-ended
+  "current" rows (@c MY_TIMESPEC_MAX) are skipped when scanning.
+
+  In debug builds, both the index and scan paths are executed and their
+  results are asserted to be equal when the DBUG_IF "test_mdev-25529" flag
+  is set.
+
+  @param thd     Current thread.
+  @param min_ts  Out parameter: minimum historical row-end timestamp.
+  @param max_ts  Out parameter: maximum historical row-end timestamp.
+
+  @retval false  Success.
+  @retval true   Handler or conversion error.
+*/
+bool TABLE::vers_get_history_range(THD *thd, my_timespec_t &min_ts,
+                                   my_timespec_t &max_ts)
+{
+  DBUG_ASSERT(versioned());
+  // Find best key
+  KEY *key= key_info, *best_key= NULL;
+  uint best_idx;
+  Field *end_field= vers_end_field();
+  const field_index_t end_field_idx= end_field->field_index;
+  for (uint idx= 0; idx < s->keys; idx++, key++)
+  {
+    /*
+      Note: we don't check keys_in_use_for_query as ALTER TABLE doesn't call
+      setup_tables().
+    */
+    DBUG_ASSERT(key->key_part->fieldnr > 0);
+    const ulong index_flags= file->index_flags(idx, 0, false);
+    if (key->key_part->fieldnr - 1 == end_field_idx &&
+        (index_flags & HA_READ_ORDER) &&
+        !(index_flags & HA_ONLY_WHOLE_INDEX) &&
+        !(key->key_part->key_part_flag & HA_REVERSE_SORT) &&
+        (!best_key || best_key->key_length > key->key_length))
+    {
+      best_key= key;
+      best_idx= idx;
+    }
+  }
+
+  int error;
+  my_timespec_t ts;
+  min_ts= MY_TIMESPEC_MAX;
+  max_ts= MY_TIMESPEC_MIN;
+#ifndef DBUG_OFF
+  my_timespec_t min_ts2, max_ts2;
+#endif /* DBUG_OFF */
+  MY_BITMAP *save_read_set=  read_set;
+  MY_BITMAP *save_write_set= write_set;
+  DBUG_ASSERT(save_read_set != &tmp_set);
+  bitmap_clear_all(&tmp_set);
+  column_bitmaps_set(&tmp_set, &tmp_set);
+  bitmap_set_bit(read_set, end_field->field_index);
+  file->column_bitmaps_signal(false);
+  DBUG_ASSERT(thd->mdl_context.is_lock_owner(MDL_key::TABLE, s->db.str,
+                                              s->table_name.str, MDL_SHARED_READ));
+  if ((error= file->ha_external_lock(thd, F_RDLCK)))
+    goto end;
+
+  if (best_key)
+  {
+    uchar search_key[MAX_KEY_LENGTH];
+    KEY *best_key_info= key_info + best_idx;
+    end_field->set_max();
+    KEY_PART_INFO *key_part= best_key_info->key_part;
+    const uint key_prefix_len= key_part[0].store_length;
+    key_copy(search_key, record[0], best_key_info, key_prefix_len);
+
+    /* Get range from index */
+    if ((error= file->ha_index_init(best_idx, true)))
+      goto end_unlock;
+
+    if (!(error= file->ha_index_first(record[0])))
+    {
+      min_ts.sec= end_field->get_timestamp(&min_ts.usec);
+      error= file->ha_index_read_map(record[0], (uchar*) search_key,
+                                     (key_part_map) 1, HA_READ_BEFORE_KEY);
+      if (!error)
+      {
+        max_ts.sec= end_field->get_timestamp(&max_ts.usec);
+      }
+    }
+
+    file->ha_index_end();
+
+    if (error == HA_ERR_END_OF_FILE || error == HA_ERR_KEY_NOT_FOUND)
+      error= 0;
+    else if (error)
+      goto end_unlock;
+
+#ifndef DBUG_OFF
+    /* Test both index and scan, compare the results between them */
+    min_ts2= min_ts;
+    max_ts2= max_ts;
+    if (DBUG_IF("test_mdev-25529"))
+      goto jump_scan;
+#endif /* DBUG_OFF */
+  }
+  else
+  {
+    push_warning_printf(thd, Sql_condition::WARN_LEVEL_WARN,
+                        WARN_VERS_SLOW_ROW_END,
+                        ER_THD(thd, WARN_VERS_SLOW_ROW_END),
+                        s->table_name.str);
+#ifndef DBUG_OFF
+jump_scan:
+#endif /* DBUG_OFF */
+    /* Get range by scan */
+    if ((error= file->ha_rnd_init(1)))
+      goto end_unlock;
+
+    /* can_continue_handler_scan() is only for heap (record changed protection) */
+    while (!(error= file->can_continue_handler_scan()) &&
+          !(error= file->ha_rnd_next(record[0])))
+    {
+      ts.sec= end_field->get_timestamp(&ts.usec);
+      if (ts == MY_TIMESPEC_MAX)
+        continue;
+      if (ts < min_ts)
+        min_ts= ts;
+      if (ts > max_ts)
+        max_ts= ts;
+    }
+
+    file->ha_rnd_end();
+#ifndef DBUG_OFF
+    if (best_key)
+    {
+      DBUG_ASSERT(DBUG_IF("test_mdev-25529"));
+      DBUG_ASSERT(min_ts == min_ts2);
+      DBUG_ASSERT(max_ts == max_ts2);
+    }
+#endif /* DBUG_OFF */
+  }
+
+  if (error == HA_ERR_END_OF_FILE)
+    error= 0;
+
+end_unlock:
+  file->ha_external_unlock(thd);
+
+end:
+  if (error)
+  {
+    myf flags= 0;
+
+    if (file->is_fatal_error(error, HA_CHECK_ALL))
+      flags|= ME_FATAL; /* Other handler errors are fatal */
+
+    file->print_error(error, MYF(flags));
+  }
+
+  column_bitmaps_set(save_read_set, save_write_set);
+  file->column_bitmaps_signal(false);
+  return (bool) error;
+}
+#endif /* WITH_PARTITION_STORAGE_ENGINE */
diff --git a/sql/sql_time.cc b/sql/sql_time.cc
index c38871c3d7896..1a8028ecfe80b 100644
--- a/sql/sql_time.cc
+++ b/sql/sql_time.cc
@@ -24,6 +24,7 @@
 #include <m_ctype.h>
 
 
+/* Daynumber from year 0 to 9999-12-31 */
 #define MAX_DAY_NUMBER 3652424L
 
 	/* Some functions to calculate dates */
@@ -604,11 +605,6 @@ void make_truncated_value_warning(THD *thd,
 }
 
 
-/* Daynumber from year 0 to 9999-12-31 */
-#define COMBINE(X)                                                      \
-               (((((X)->day * 24LL + (X)->hour) * 60LL +                \
-                   (X)->minute) * 60LL + (X)->second)*1000000LL +       \
-                   (X)->second_part)
 #define GET_PART(X, N) X % N ## LL; X/= N ## LL
 
 bool date_add_interval(THD *thd, MYSQL_TIME *ltime, interval_type int_type,
@@ -648,7 +644,7 @@ bool date_add_interval(THD *thd, MYSQL_TIME *ltime, interval_type int_type,
     if (time_type != MYSQL_TIMESTAMP_TIME)
       ltime->day+= calc_daynr(ltime->year, ltime->month, 1) - 1;
 
-    usec= COMBINE(ltime) + sign*COMBINE(&interval);
+    usec= interval2usec(ltime) + sign * interval2usec(&interval);
 
     if (usec < 0)
     {
diff --git a/sql/sql_time.h b/sql/sql_time.h
index 255ebfeb663e3..3cb07e82f3ef7 100644
--- a/sql/sql_time.h
+++ b/sql/sql_time.h
@@ -165,4 +165,36 @@ longlong pack_time(const MYSQL_TIME *my_time);
 void unpack_time(longlong packed, MYSQL_TIME *my_time,
                  enum_mysql_timestamp_type ts_type);
 
+/**
+  Convert an interval value to a total number of seconds.
+
+  The template parameter @c T must provide @c day, @c hour, @c minute, and
+  @c second members.
+
+  @param x  Pointer to an interval-like value.
+
+  @return  Total number of seconds represented by @p x.
+*/
+template <typename T>
+inline longlong interval2sec(T x)
+{
+  return ((x->day * 24LL + x->hour) * 60LL + x->minute) * 60LL + x->second;
+}
+
+/**
+  Convert an interval value to a total number of microseconds.
+
+  Delegates to interval2sec() and adds @c x->second_part. The template
+  parameter @c T must provide all members required by interval2sec() plus
+  a @c second_part member.
+
+  @param x  Pointer to an interval-like value.
+
+  @return  Total number of microseconds represented by @p x.
+*/
+template <typename T>
+inline longlong interval2usec(T x)
+{
+  return interval2sec(x) * 1000000LL + x->second_part;
+}
 #endif /* SQL_TIME_INCLUDED */
diff --git a/sql/sql_type.cc b/sql/sql_type.cc
index 454612e34e4fb..e45b3e518797d 100644
--- a/sql/sql_type.cc
+++ b/sql/sql_type.cc
@@ -396,6 +396,23 @@ Temporal_hybrid::Temporal_hybrid(THD *thd, Item *item, date_mode_t fuzzydate)
 }
 
 
+/**
+  Construct a temporal value from a high-precision timestamp.
+
+  Converts @p time.sec to broken-down local time in the current session
+  time zone and stores @p time.usec as the sub-second part.
+
+  @param thd   Current thread.
+  @param time  Timestamp value (seconds + microseconds) to convert.
+*/
+Temporal_hybrid::Temporal_hybrid(THD *thd, my_timespec_t time)
+{
+  thd->variables.time_zone->gmt_sec_to_TIME(this, time.sec);
+  DBUG_ASSERT(time.usec < 1000000);
+  second_part= time.usec;
+}
+
+
 uint Timestamp::binary_length_to_precision(uint length)
 {
   switch (length) {
diff --git a/sql/sql_type.h b/sql/sql_type.h
index 7b6e705a86379..77bfc39517935 100644
--- a/sql/sql_type.h
+++ b/sql/sql_type.h
@@ -1391,6 +1391,7 @@ class Temporal_hybrid: public Temporal
     else
       make_from_decimal(thd, warn, nr, mode);
   }
+  Temporal_hybrid(THD *thd, my_timespec_t time);
   // End of constructors
 
   bool copy_valid_value_to_mysql_time(MYSQL_TIME *ltime) const
@@ -1420,8 +1421,9 @@ class Temporal_hybrid: public Temporal
     if (!is_valid_temporal())
       return NULL;
     str->set_charset(&my_charset_numeric);
-    if (!str->alloc(MAX_DATE_STRING_REP_LENGTH))
-      str->length(my_TIME_to_str(this, const_cast<char*>(str->ptr()), dec));
+    if (str->alloc(MAX_DATE_STRING_REP_LENGTH))
+      return NULL;
+    str->length(my_TIME_to_str(this, const_cast<char*>(str->ptr()), dec));
     return str;
   }
   const MYSQL_TIME *get_mysql_time() const
diff --git a/sql/sql_yacc.yy b/sql/sql_yacc.yy
index 6ab9dff16ad4f..f42136775d0f1 100644
--- a/sql/sql_yacc.yy
+++ b/sql/sql_yacc.yy
@@ -7855,8 +7855,12 @@ alter_commands:
           }
         | alter_list
           opt_partitioning
+        | partitioning
+          alter_list
         | alter_list
           remove_partitioning
+        | remove_partitioning
+          alter_list
         | remove_partitioning
         | partitioning
 /*
diff --git a/sql/table.h b/sql/table.h
index ba15cf45a1257..2ebad4c3586ae 100644
--- a/sql/table.h
+++ b/sql/table.h
@@ -2024,6 +2024,8 @@ struct TABLE
 #ifdef WITH_PARTITION_STORAGE_ENGINE
   bool vers_switch_partition(THD *thd, TABLE_LIST *table_list,
                              Open_table_context *ot_ctx);
+  bool vers_get_history_range(THD *thd, my_timespec_t &min_ts,
+                              my_timespec_t &max_ts);
 #endif
   bool vers_implicit() const;