MDEV-21155 Assertion with versioned table upon DELETE from view of view after replacing first view

When view is merged by DT_MERGE_FOR_INSERT it is then skipped from
processing and doesn't update WHERE clause with
vers_setup_conds(). Note that view itself cannot work in
vers_setup_conds() because it doesn't have row_start, row_end
fields. Thus it is required to descend down to material TABLE_LIST
through calls of mysql_derived_prepare() and run vers_setup_conds()
from there. Luckily, all views (views of views, views of views of
views, etc.) are linked in one list through next_global pointer, so we
can skip all views of views and get straight to non-view TABLE_LIST by
checking its merge_underlying_list property for zero value (it is
assigned by DT_MERGE_FOR_INSERT for merged derived tables).

We have to do that only for UPDATE and DELETE. Other DML commands
don't use WHERE clause.

MDEV-21146 Assertion `m_lock_type == 2' in handler::ha_drop_table upon LOAD DATA

LOAD DATA does not use WHERE and the above call of vers_setup_conds()
is not needed. unit->prepare() led to wrongly locked temporary table.

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

@@ -160,6 +160,7 @@ period for system_time (row_start, row_end)
 ) with system versioning;
 insert into t1 values (1), (2);
 create or replace view v1 as select * from t1 where x > 1;
+# update, delete
 update v1 set x= x + 1;
 select *, check_row(row_start, row_end) from t1 for system_time all order by x;
 x	check_row(row_start, row_end)
@@ -211,5 +212,70 @@ x	check_row(row_start, row_end)
 1	CURRENT ROW
 2	HISTORICAL ROW
 3	HISTORICAL ROW
+# replace
+create or replace table t1 (
+x int primary key, y int,
+row_start SYS_DATATYPE as row start invisible,
+row_end SYS_DATATYPE as row end invisible,
+period for system_time (row_start, row_end)
+) with system versioning;
+insert into t1 values (1, 0), (2, 0);
+create or replace view v1 as select * from t1 where x > 1;
+replace v1 values (1, 1);
+replace v1 values (2, 1);
+replace v1 values (3, 1);
+# REPLACE ignores VIEW condition because itself doesn't use WHERE
+select *, check_row(row_start, row_end) from t1 for system_time all order by x, row_end;
+x	y	check_row(row_start, row_end)
+1	0	HISTORICAL ROW
+1	1	CURRENT ROW
+2	0	HISTORICAL ROW
+2	1	CURRENT ROW
+3	1	CURRENT ROW
+# insert-select, on duplicate key
+insert v1 select * from t1 where x = 1 on duplicate key update x = v1.x - 1;
+select *, check_row(row_start, row_end) from t1 for system_time all order by x, row_end;
+x	y	check_row(row_start, row_end)
+0	1	CURRENT ROW
+1	0	HISTORICAL ROW
+1	1	HISTORICAL ROW
+2	0	HISTORICAL ROW
+2	1	CURRENT ROW
+3	1	CURRENT ROW
 drop view v1, v2;
 drop tables t1, t2;
+#
+# MDEV-21146 Assertion `m_lock_type == 2' in handler::ha_drop_table upon LOAD DATA
+#
+create table t1 (a int);
+create view v1 as select * from t1;
+create or replace table t1 (b int) with system versioning;
+load data infile 'xx' into table v1;
+ERROR HY000: View 'test.v1' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
+drop view v1;
+drop table t1;
+#
+# MDEV-21155 Assertion with versioned table upon DELETE from view of view after replacing first view
+#
+create table t1 (a int);
+insert into t1 values (1);
+create table t2 (
+b int,
+row_start SYS_DATATYPE as row start invisible,
+row_end SYS_DATATYPE as row end invisible,
+period for system_time (row_start, row_end)
+) with system versioning;
+insert into t2 values (2);
+create view v1 as select * from t1;
+create view v2 as select * from v1;
+create or replace view v1 as select * from t2;
+delete from v2;
+select * from t1;
+a
+1
+select *, check_row(row_start, row_end) from t2 for system_time all;
+b	check_row(row_start, row_end)
+2	HISTORICAL ROW
+drop view v2;
+drop view v1;
+drop table t1, t2;

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

@@ -136,6 +136,7 @@ eval create or replace table t1 (
 ) with system versioning;
 insert into t1 values (1), (2);
 create or replace view v1 as select * from t1 where x > 1;
+--echo # update, delete
 update v1 set x= x + 1;
 select *, check_row(row_start, row_end) from t1 for system_time all order by x;
 insert v1 values (4);
@@ -153,8 +154,63 @@ select *, check_row(row_start, row_end) from t2 for system_time all order by x;
 delete v1, v2 from v1 join v2 where v1.x = v2.x + 2;
 select *, check_row(row_start, row_end) from t1 for system_time all order by x;
 select *, check_row(row_start, row_end) from t2 for system_time all order by x;
-
+--echo # replace
+--replace_result $sys_datatype_expl SYS_DATATYPE
+eval create or replace table t1 (
+  x int primary key, y int,
+  row_start $sys_datatype_expl as row start invisible,
+  row_end $sys_datatype_expl as row end invisible,
+  period for system_time (row_start, row_end)
+) with system versioning;
+insert into t1 values (1, 0), (2, 0);
+create or replace view v1 as select * from t1 where x > 1;
+replace v1 values (1, 1);
+replace v1 values (2, 1);
+replace v1 values (3, 1);
+--echo # REPLACE ignores VIEW condition because itself doesn't use WHERE
+select *, check_row(row_start, row_end) from t1 for system_time all order by x, row_end;
+--echo # insert-select, on duplicate key
+insert v1 select * from t1 where x = 1 on duplicate key update x = v1.x - 1;
+select *, check_row(row_start, row_end) from t1 for system_time all order by x, row_end;
 drop view v1, v2;
 drop tables t1, t2;
 
+--echo #
+--echo # MDEV-21146 Assertion `m_lock_type == 2' in handler::ha_drop_table upon LOAD DATA
+--echo #
+create table t1 (a int);
+create view v1 as select * from t1;
+create or replace table t1 (b int) with system versioning;
+--error ER_VIEW_INVALID
+load data infile 'xx' into table v1;
+
+# cleanup
+drop view v1;
+drop table t1;
+
+--echo #
+--echo # MDEV-21155 Assertion with versioned table upon DELETE from view of view after replacing first view
+--echo #
+create table t1 (a int);
+insert into t1 values (1);
+--replace_result $sys_datatype_expl SYS_DATATYPE
+eval create table t2 (
+  b int,
+  row_start $sys_datatype_expl as row start invisible,
+  row_end $sys_datatype_expl as row end invisible,
+  period for system_time (row_start, row_end)
+) with system versioning;
+insert into t2 values (2);
+create view v1 as select * from t1;
+create view v2 as select * from v1;
+create or replace view v1 as select * from t2;
+delete from v2;
+select * from t1;
+select *, check_row(row_start, row_end) from t2 for system_time all;
+
+# cleanup
+drop view v2;
+drop view v1;
+drop table t1, t2;
+
 --source suite/versioning/common_finish.inc

sql/sql_derived.cc

@@ -692,12 +692,27 @@ bool mysql_derived_prepare(THD *thd, LEX *lex, TABLE_LIST *derived)
   {
     /*
        System versioned tables may still require to get versioning conditions
-       (when updating view). See vers_setup_conds().
+       when modifying view (see vers_setup_conds()). Only UPDATE and DELETE are
+       affected because they use WHERE condition.
     */
     if (!unit->prepared &&
         derived->table->versioned() &&
-        (res= unit->prepare(derived, derived->derived_result, 0)))
+        derived->merge_underlying_list &&
-      goto exit;
+        /* choose only those merged views that do not select from other views */
+        !derived->merge_underlying_list->merge_underlying_list)
+    {
+      switch (thd->lex->sql_command)
+      {
+      case SQLCOM_DELETE:
+      case SQLCOM_DELETE_MULTI:
+      case SQLCOM_UPDATE:
+      case SQLCOM_UPDATE_MULTI:
+        if ((res= unit->prepare(derived, derived->derived_result, 0)))
+          goto exit;
+      default:
+        break;
+      }
+    }
     DBUG_RETURN(FALSE);
   }
 
@@ -817,7 +832,7 @@ exit:
   {
     if (!derived->is_with_table_recursive_reference())
     {
-      if (derived->table)
+      if (derived->table && derived->table->s->tmp_table)
         free_tmp_table(thd, derived->table);
       delete derived->derived_result;
     }

sql/table.h

@@ -321,7 +321,7 @@ typedef struct st_grant_info
 
 enum tmp_table_type
 {
-  NO_TMP_TABLE, NON_TRANSACTIONAL_TMP_TABLE, TRANSACTIONAL_TMP_TABLE,
+  NO_TMP_TABLE= 0, NON_TRANSACTIONAL_TMP_TABLE, TRANSACTIONAL_TMP_TABLE,
   INTERNAL_TMP_TABLE, SYSTEM_TMP_TABLE
 };
 enum release_type { RELEASE_NORMAL, RELEASE_WAIT_FOR_DROP };