MDEV-28271 Assertion on TRUNCATE PARTITION for PARTITION BY SYSTEM_TIME

Like in MDEV-27217 vers_set_hist_part() for LIMIT depends on all
partitions selected in read_partitions. That bugfix just disabled
partition selection for DELETE with this check:

  if (table->pos_in_table_list &&
      table->pos_in_table_list->partition_names)
  {
    return HA_ERR_PARTITION_LIST;
  }

ALTER TABLE TRUNCATE PARTITION is a different story. First, it doesn't
update pos_in_table_list->partition_names, but
thd->lex->alter_info.partition_names. But we cannot depend on that
since alter_info will be stale for DML. Second, we should not disable
TRUNCATE PARTITION for that to be consistent with TRUNCATE TABLE
behavior.

Now we don't do vers_set_hist_part() for ALTER TABLE as this command
is not DML, so it does not produce history.

mysql-test/suite/versioning/r/partition.result

@@ -839,5 +839,77 @@ p0	10
 p1	0
 pn	90
 drop table t1;
+#
+# MDEV-28271 Assertion on TRUNCATE PARTITION for PARTITION BY SYSTEM_TIME
+#
+create table t1 (x int) with system versioning
+partition by system_time limit 1 (
+partition p0 history,
+partition p1 history,
+partition pn current);
+insert into t1 values (0);
+update t1 set x= x + 1;
+update t1 set x= x + 1;
+update t1 set x= x + 1;
+update t1 set x= x + 1;
+select * from t1 partition (p0);
+x
+0
+1
+select * from t1 partition (p1);
+x
+2
+3
+select * from t1 partition (pn);
+x
+4
+# TRUNCATE TABLE deletes history and current data
+truncate table t1;
+select * from t1 partition (p0);
+x
+select * from t1 partition (p1);
+x
+select * from t1 partition (pn);
+x
+insert into t1 values (0);
+update t1 set x= x + 1;
+update t1 set x= x + 1;
+update t1 set x= x + 1;
+update t1 set x= x + 1;
+# TRUNCATE PARTITION ALL does the same
+alter table t1 truncate partition all;
+select * from t1 partition (p0);
+x
+select * from t1 partition (p1);
+x
+select * from t1 partition (pn);
+x
+insert into t1 values (0);
+update t1 set x= x + 1;
+update t1 set x= x + 1;
+update t1 set x= x + 1;
+update t1 set x= x + 1;
+# TRUNCATE PARTITION deletes data from HISTORY partition
+alter table t1 truncate partition p1;
+select * from t1 partition (p0);
+x
+0
+1
+select * from t1 partition (p1);
+x
+select * from t1 partition (pn);
+x
+4
+# or from CURRENT partition
+alter table t1 truncate partition pn;
+select * from t1 partition (p0);
+x
+0
+1
+select * from t1 partition (p1);
+x
+select * from t1 partition (pn);
+x
+drop table t1;
 # End of 10.3 tests
 set global innodb_stats_persistent= @save_persistent;

mysql-test/suite/versioning/t/partition.test

@@ -822,6 +822,66 @@ from information_schema.partitions
 where table_name = 't1';
  # Cleanup
 drop table t1;
+
+--echo #
+--echo # MDEV-28271 Assertion on TRUNCATE PARTITION for PARTITION BY SYSTEM_TIME
+--echo #
+create table t1 (x int) with system versioning
+partition by system_time limit 1 (
+  partition p0 history,
+  partition p1 history,
+  partition pn current);
+
+insert into t1 values (0);
+update t1 set x= x + 1;
+update t1 set x= x + 1;
+update t1 set x= x + 1;
+update t1 set x= x + 1;
+
+select * from t1 partition (p0);
+select * from t1 partition (p1);
+select * from t1 partition (pn);
+
+--echo # TRUNCATE TABLE deletes history and current data
+--disable_warnings
+truncate table t1;
+--enable_warnings
+select * from t1 partition (p0);
+select * from t1 partition (p1);
+select * from t1 partition (pn);
+
+insert into t1 values (0);
+update t1 set x= x + 1;
+update t1 set x= x + 1;
+update t1 set x= x + 1;
+update t1 set x= x + 1;
+
+--echo # TRUNCATE PARTITION ALL does the same
+alter table t1 truncate partition all;
+select * from t1 partition (p0);
+select * from t1 partition (p1);
+select * from t1 partition (pn);
+
+insert into t1 values (0);
+update t1 set x= x + 1;
+update t1 set x= x + 1;
+update t1 set x= x + 1;
+update t1 set x= x + 1;
+
+--echo # TRUNCATE PARTITION deletes data from HISTORY partition
+alter table t1 truncate partition p1;
+select * from t1 partition (p0);
+select * from t1 partition (p1);
+select * from t1 partition (pn);
+
+--echo # or from CURRENT partition
+alter table t1 truncate partition pn;
+select * from t1 partition (p0);
+select * from t1 partition (p1);
+select * from t1 partition (pn);
+
+drop table t1;
+
 --echo # End of 10.3 tests
 
 set global innodb_stats_persistent= @save_persistent;

sql/ha_partition.cc

@@ -4034,6 +4034,7 @@ int ha_partition::external_lock(THD *thd, int lock_type)
          only for versioned DML. */
       thd->lex->sql_command != SQLCOM_SELECT &&
       thd->lex->sql_command != SQLCOM_INSERT_SELECT &&
+      thd->lex->sql_command != SQLCOM_ALTER_TABLE &&
       (error= m_part_info->vers_set_hist_part(thd)))
       goto err_handler;
   }