MDEV-25529 Auto-create: Pre-existing historical data is not partitioned as specified by ALTER

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_ */

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;

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

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;