Bug#24834622 - ASSERT IN UPDATING VIEW METADATA FOR SYS SCHEMA VIEW.

While updating view columns metadata, assert condition is hit
for the datetime type column with default value as bitmap
TABLE::read_set is not set.

TABLE has a bitmap read_set. A bit in this bitmap is set for a
field of a table used in the query. But this bitmap is not set
(for outer-most query block) while resolving derived tables.
A flag THD::derived_tables_processing is used to indicate the
derived table processing.

DDL operation on a table, views or stored function(sf) updates
a view columns metadata if there are any views referencing them.
The view columns metadata is updated as below,

  * List all the views using table, views or sf used in the DDL
    operation and even other views dependent on view(s) already
    included in the list.

  * For all views in the list,
      ** Prepare query expression for a view query with the new
         definition of table/view/sf.

      ** Update view columns metadata using the query expression
         prepared for a view query.

    (In error scenarios mark view as invalid and continue with
     next view in list.)

While preparing query expression for a view, if the derived
table processing fails in a situation like missing other table,
view or sf (while preparing the query expression of the derived
table) then the flag THD::derived_tables_processing is not reset
in the current code. This affects processing next view in the
list and we end-up not setting read_set flags in TABLE. Hence
assert condition to check bitmaps THD::read_set while accessing
fields (of type datatime in this scenario) fails.

Modified code to reset THD::derived_tables_processing flag in
in all error handling code path while resolving derived tables to
fix this issue.

Author: phulakun

mysql-test/r/dd_view_columns.result

@@ -600,3 +600,39 @@ DROP TABLES t1,t3;
 DROP FUNCTION sf1;
 DEALLOCATE PREPARE check_view_columns;
 DEALLOCATE PREPARE check_view_status;
+#
+# Bug#24834622 - ASSERT IN UPDATING VIEW METADATA FOR SYS SCHEMA VIEW.
+#
+# Creating views with dependency on view/base table/stored functions
+# as below,
+#    View v2 is dependent on stored function f2.
+#    View v1 is dependent on stored function f1 and view v2.
+#    View z1 is dependent on view v2 and table t1 (having datetime column).
+CREATE TABLE t1 (f1 DATETIME default '2016-11-01');
+CREATE FUNCTION f1() RETURNS INT return 1;
+CREATE FUNCTION f2() RETURNS INT return 2;
+CREATE VIEW v2 AS SELECT f2() AS f2;
+CREATE VIEW v1 AS SELECT v2.f2 AS f2,
+a3.x as f3 from v2,
+(SELECT a.x FROM (SELECT f1() AS x)
+as a HAVING a.x=1) as a3;
+CREATE VIEW z1 AS SELECT t1.f1 AS f1, v2.f2 AS f2 FROM t1, v2;
+# View v1 is dependent on stored function f1 and view v2.
+# Dropping stored function f1 leaves view v1 in invalid state.
+DROP FUNCTION f1;
+# View v2 is dependent on stored function f2.
+# Dropping stored function f2 leaves view v2 and views using v2
+# (i.e v1 and z1) in invalid state.
+DROP FUNCTION f2;
+# Recreating the stored function f2 updates columns of dependent view v2
+# and views dependent on v2 (i.e. v1 and z1) in DD tables COLUMNS.
+# View v1 is dependent on f1 too. So parsing view v1 fails while
+# updating views column metadata.
+# Without fix, THD::derived_tables_processing is not unset to false
+# on view v1 parse failure. This causes an assert condition failure while
+# updating metadata of datatime type column of view z1 as read flag
+# for column is not set with the THD::derived_tables_processing on.
+CREATE FUNCTION f2() RETURNS INT return 2;
+DROP FUNCTION f2;
+DROP VIEW v1, v2, z1;
+DROP TABLE t1;

mysql-test/t/dd_view_columns.test

@@ -466,3 +466,50 @@ DROP TABLES t1,t3;
 DROP FUNCTION sf1;
 DEALLOCATE PREPARE check_view_columns;
 DEALLOCATE PREPARE check_view_status;
+
+
+--echo #
+--echo # Bug#24834622 - ASSERT IN UPDATING VIEW METADATA FOR SYS SCHEMA VIEW.
+--echo #
+
+--echo # Creating views with dependency on view/base table/stored functions
+--echo # as below,
+--echo #    View v2 is dependent on stored function f2.
+--echo #    View v1 is dependent on stored function f1 and view v2.
+--echo #    View z1 is dependent on view v2 and table t1 (having datetime column).
+
+CREATE TABLE t1 (f1 DATETIME default '2016-11-01');
+
+CREATE FUNCTION f1() RETURNS INT return 1;
+CREATE FUNCTION f2() RETURNS INT return 2;
+
+CREATE VIEW v2 AS SELECT f2() AS f2;
+CREATE VIEW v1 AS SELECT v2.f2 AS f2,
+                         a3.x as f3 from v2,
+                  (SELECT a.x FROM (SELECT f1() AS x)
+                          as a HAVING a.x=1) as a3;
+CREATE VIEW z1 AS SELECT t1.f1 AS f1, v2.f2 AS f2 FROM t1, v2;
+
+--echo # View v1 is dependent on stored function f1 and view v2.
+--echo # Dropping stored function f1 leaves view v1 in invalid state.
+DROP FUNCTION f1;
+
+--echo # View v2 is dependent on stored function f2.
+--echo # Dropping stored function f2 leaves view v2 and views using v2
+--echo # (i.e v1 and z1) in invalid state.
+DROP FUNCTION f2;
+
+--echo # Recreating the stored function f2 updates columns of dependent view v2
+--echo # and views dependent on v2 (i.e. v1 and z1) in DD tables COLUMNS.
+--echo # View v1 is dependent on f1 too. So parsing view v1 fails while
+--echo # updating views column metadata.
+--echo # Without fix, THD::derived_tables_processing is not unset to false
+--echo # on view v1 parse failure. This causes an assert condition failure while
+--echo # updating metadata of datatime type column of view z1 as read flag
+--echo # for column is not set with the THD::derived_tables_processing on.
+CREATE FUNCTION f2() RETURNS INT return 2;
+
+# Cleanup
+DROP FUNCTION f2;
+DROP VIEW v1, v2, z1;
+DROP TABLE t1;

sql/sql_derived.cc

@@ -257,14 +257,51 @@ bool TABLE_LIST::resolve_derived(THD *thd, bool apply_semijoin)
 {
   DBUG_ENTER("TABLE_LIST::resolve_derived");
 
+  /*
+    Helper class which takes care of restoration of THD::LEX::allow_sum_func
+    and THD::derived_tables_processing. These members are changed in this
+    method scope for resolving derived tables.
+  */
+  class Context_handler
+  {
+  public:
+    Context_handler(THD *thd)
+      : m_thd(thd),
+        m_allow_sum_func_saved(thd->lex->allow_sum_func),
+        m_derived_tables_processing_saved(thd->derived_tables_processing)
+    {
+      /*
+        Since derived tables do not allow outer references, they cannot allow
+        aggregation to occur in any outer query blocks.
+      */
+      m_thd->lex->allow_sum_func= 0;
+
+      m_thd->derived_tables_processing= true;
+    }
+
+    ~Context_handler()
+    {
+      m_thd->lex->allow_sum_func= m_allow_sum_func_saved;
+      m_thd->derived_tables_processing= m_derived_tables_processing_saved;
+    }
+  private:
+    // Thread handle.
+    THD *m_thd;
+
+    // Saved state of THD::LEX::allow_sum_func.
+    nesting_map m_allow_sum_func_saved;
+
+    // Saved state of THD::derived_tables_processing.
+    bool m_derived_tables_processing_saved;
+  };
+
   if (!is_view_or_derived() || is_merged())
     DBUG_RETURN(false);
 
   // Dummy derived tables for recursive references disappear before this stage
   DBUG_ASSERT(this != select_lex->recursive_reference);
 
-  const bool derived_tables_saved= thd->derived_tables_processing;
-  thd->derived_tables_processing= true;
+  Context_handler ctx_handler(thd);
 
   if (derived->prepare_limit(thd, derived->global_parameters()))
     DBUG_RETURN(true);              /* purecov: inspected */
@@ -386,13 +423,6 @@ bool TABLE_LIST::resolve_derived(THD *thd, bool apply_semijoin)
   if (!(derived_result= new (thd->mem_root) Query_result_union(thd)))
     DBUG_RETURN(true);              /* purecov: inspected */
 
-  /*
-    Since derived tables do not allow outer references, they cannot allow
-    aggregation to occur in any outer query blocks.
-  */
-  nesting_map allow_sum_func_saved= thd->lex->allow_sum_func;
-  thd->lex->allow_sum_func= 0;
-
   /*
     Prepare the underlying query expression of the derived table.
     The SELECT_STRAIGHT_JOIN option prevents semi-join transformation.
@@ -419,10 +449,6 @@ bool TABLE_LIST::resolve_derived(THD *thd, bool apply_semijoin)
     set_privileges(SELECT_ACL);
   }
 
-  thd->lex->allow_sum_func= allow_sum_func_saved;
-
-  thd->derived_tables_processing= derived_tables_saved;
-
   DBUG_RETURN(false);
 }