MDEV-12395: DROP PARTITION does not work as expected when table has DEFAULT LIST partition

Data loss in case of partituon removing is documented => do not try to prevent it

mysql-test/r/partition_default.result

@@ -921,9 +921,6 @@ explain partitions select * from t1 where a=10 and b=10;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	p0	system	NULL	NULL	NULL	NULL	1	
 alter table t1 drop partition p2;
-ERROR HY000: Table has no partition for value 2
-delete from t1 where a=2;
-alter table t1 drop partition p2;
 show create table t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
@@ -1069,9 +1066,6 @@ explain partitions select * from t1 where a=10 and b=10;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	p0	system	NULL	NULL	NULL	NULL	1	
 alter table t1 drop partition p2;
-ERROR HY000: Table has no partition for value from column_list
-delete from t1 where a=2;
-alter table t1 drop partition p2;
 show create table t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
@@ -1125,10 +1119,10 @@ alter table t1 add partition
 (partition p0 VALUES IN (2,3));
 select partition_name, table_rows from INFORMATION_SCHEMA.PARTITIONS where table_name='t1';
 partition_name	table_rows
-p0	2
+p0	0
 p1	1
 p2	1
-pd	0
+pd	2
 drop table t1;
 create table t1 (a int, b int)
 PARTITION BY LIST COLUMNS(a,b)
@@ -1233,3 +1227,41 @@ select * from t1 where i is null;
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	p0	system	NULL	NULL	NULL	NULL	1	
 drop table t1;
+#
+# MDEV-12395: DROP PARTITION does not work as expected when
+# table has DEFAULT LIST partition
+#
+CREATE TABLE t1 (i INT)
+PARTITION BY LIST (i)
+(PARTITION p VALUES IN (1,2,3,4),
+PARTITION pdef DEFAULT);
+INSERT INTO t1 VALUES (1),(10);
+ALTER TABLE t1 DROP PARTITION p;
+SELECT * FROM t1;
+i
+10
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `i` int(11) DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+ PARTITION BY LIST (i)
+(PARTITION pdef DEFAULT ENGINE = MyISAM)
+DROP TABLE t1;
+CREATE TABLE t1 (i INT)
+PARTITION BY LIST (i)
+(PARTITION p VALUES IN (1,2,3,4),
+PARTITION pdef DEFAULT);
+INSERT INTO t1 VALUES (1),(10);
+ALTER TABLE t1 DROP PARTITION pdef;
+SELECT * FROM t1;
+i
+1
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `i` int(11) DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+ PARTITION BY LIST (i)
+(PARTITION p VALUES IN (1,2,3,4) ENGINE = MyISAM)
+DROP TABLE t1;

mysql-test/t/partition_default.test

@@ -326,9 +326,6 @@ select partition_name, table_rows from INFORMATION_SCHEMA.PARTITIONS where table
 explain partitions select * from t1 where a=2 and b=5;
 explain partitions select * from t1 where a=10 and b=10;
 
---error ER_NO_PARTITION_FOR_GIVEN_VALUE
-alter table t1 drop partition p2;
-delete from t1 where a=2;
 alter table t1 drop partition p2;
 show create table t1;
 select * from t1;
@@ -395,9 +392,6 @@ select partition_name, table_rows from INFORMATION_SCHEMA.PARTITIONS where table
 explain partitions select * from t1 where a=2 and b=5;
 explain partitions select * from t1 where a=10 and b=10;
 
---error ER_NO_PARTITION_FOR_GIVEN_VALUE
-alter table t1 drop partition p2;
-delete from t1 where a=2;
 alter table t1 drop partition p2;
 show create table t1;
 select * from t1;
@@ -520,3 +514,29 @@ explain partitions
 select * from t1 where i is null;
 
 drop table t1;
+
+
+--echo #
+--echo # MDEV-12395: DROP PARTITION does not work as expected when
+--echo # table has DEFAULT LIST partition
+--echo #
+
+CREATE TABLE t1 (i INT)
+  PARTITION BY LIST (i)
+  (PARTITION p VALUES IN (1,2,3,4),
+   PARTITION pdef DEFAULT);
+INSERT INTO t1 VALUES (1),(10);
+ALTER TABLE t1 DROP PARTITION p;
+SELECT * FROM t1;
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
+
+CREATE TABLE t1 (i INT)
+  PARTITION BY LIST (i)
+  (PARTITION p VALUES IN (1,2,3,4),
+   PARTITION pdef DEFAULT);
+INSERT INTO t1 VALUES (1),(10);
+ALTER TABLE t1 DROP PARTITION pdef;
+SELECT * FROM t1;
+SHOW CREATE TABLE t1;
+DROP TABLE t1;

sql/sql_partition.cc

@@ -4842,8 +4842,7 @@ uint prep_alter_part_table(THD *thd, TABLE *table, Alter_info *alter_info,
       my_error(ER_PARTITION_FUNCTION_FAILURE, MYF(0));
       goto err;
     }
-    if ((flags & (HA_FAST_CHANGE_PARTITION | HA_PARTITION_ONE_PHASE)) != 0 &&
-        !tab_part_info->has_default_partititon())
+    if ((flags & (HA_FAST_CHANGE_PARTITION | HA_PARTITION_ONE_PHASE)) != 0)
     {
       /*
         "Fast" change of partitioning is supported in this case.