MDEV-22602 Disable UPDATE CASCADE for SQL constraints

CHECK constraint is checked by check_expression() which walks its
items and gets into Item_field::check_vcol_func_processor() to check
for conformity with foreign key list.

WITHOUT OVERLAPS is checked for same conformity in
mysql_prepare_create_table().

Long uniques are already impossible with InnoDB foreign keys. See
ER_CANT_CREATE_TABLE in test case.

2 accompanying bugs fixed (test main.constraints failed):

1. check->name.str lived on SP execute mem_root while "check" obj
itself lives on SP main mem_root. On second SP execute check->name.str
had garbage data. Fixed by allocating from thd->stmt_arena->mem_root
which is SP main mem_root.

2. CHECK_CONSTRAINT_IF_NOT_EXISTS value was mixed with
VCOL_FIELD_REF. VCOL_FIELD_REF is assigned in check_expression() and
then detected as CHECK_CONSTRAINT_IF_NOT_EXISTS in
handle_if_exists_options().

Existing cases for MDEV-16932 in main.constraints cover both fixes.

Author: midenok

mysql-test/suite/innodb/r/foreign_key.result

@@ -766,3 +766,21 @@ ALTER TABLE t1 ADD FOREIGN KEY (a) REFERENCES t1 (b);
 ERROR HY000: Can't create table `test`.`t1` (errno: 150 "Foreign key constraint is incorrectly formed")
 DROP TABLE t1;
 # End of 10.5 tests
+#
+# MDEV-22602 Disable UPDATE CASCADE for SQL constraints
+#
+# TODO: enable them after MDEV-16417 is finished
+create or replace table t1 (a int primary key) engine=innodb;
+create or replace table t2 (a int, check(a > 0), foreign key(a) references t1(a) on update cascade) engine=innodb;
+ERROR HY000: Function or expression 'a' cannot be used in the CHECK clause of `CONSTRAINT_1`
+create or replace table t1 (f1 int, f2 date, f3 date, key(f1,f3,f2)) engine=innodb;
+create or replace table t2 (
+a int, s date, e date,
+period for p (s, e),
+primary key (a, p without overlaps),
+foreign key (a, e, s) references t1 (f1, f3, f2) on delete cascade on update cascade) engine=innodb;
+ERROR HY000: Key `PRIMARY` cannot have WITHOUT OVERLAPS
+create or replace table t1 (a varchar(4096) unique) engine=innodb;
+create or replace table t2 (pk int primary key, a varchar(4096) unique, foreign key(a) references t1(a) on update cascade) engine=innodb;
+ERROR HY000: Can't create table `test`.`t2` (errno: 150 "Foreign key constraint is incorrectly formed")
+drop table t1;

mysql-test/suite/innodb/t/foreign_key.test

@@ -741,4 +741,27 @@ DROP TABLE t1;
 
 --echo # End of 10.5 tests
 
+--echo #
+--echo # MDEV-22602 Disable UPDATE CASCADE for SQL constraints
+--echo #
+--echo # TODO: enable them after MDEV-16417 is finished
+create or replace table t1 (a int primary key) engine=innodb;
+--error ER_GENERATED_COLUMN_FUNCTION_IS_NOT_ALLOWED
+create or replace table t2 (a int, check(a > 0), foreign key(a) references t1(a) on update cascade) engine=innodb;
+
+create or replace table t1 (f1 int, f2 date, f3 date, key(f1,f3,f2)) engine=innodb;
+--error ER_KEY_CANT_HAVE_WITHOUT_OVERLAPS
+create or replace table t2 (
+  a int, s date, e date,
+  period for p (s, e),
+  primary key (a, p without overlaps),
+  foreign key (a, e, s) references t1 (f1, f3, f2) on delete cascade on update cascade) engine=innodb;
+
+# FK on long unique is already disabled
+create or replace table t1 (a varchar(4096) unique) engine=innodb;
+--error ER_CANT_CREATE_TABLE
+create or replace table t2 (pk int primary key, a varchar(4096) unique, foreign key(a) references t1(a) on update cascade) engine=innodb;
+
+drop table t1;
+
 --source include/wait_until_count_sessions.inc

sql/field.cc

@@ -10191,11 +10191,12 @@ void Column_definition::create_length_to_internal_length_newdecimal()
 
 
 bool check_expression(Virtual_column_info *vcol, const LEX_CSTRING *name,
-                      enum_vcol_info_type type)
+                      enum_vcol_info_type type, Alter_info *alter_info)
 
 {
   bool ret;
   Item::vcol_func_processor_result res;
+  res.alter_info= alter_info;
 
   if (!vcol->name.length)
     vcol->name= *name;
@@ -10204,7 +10205,6 @@ bool check_expression(Virtual_column_info *vcol, const LEX_CSTRING *name,
     Walk through the Item tree checking if all items are valid
     to be part of the virtual column
   */
-  res.errors= 0;
   ret= vcol->expr->walk(&Item::check_vcol_func_processor, 0, &res);
   vcol->flags= res.errors;
 

sql/field.h

@@ -551,6 +551,7 @@ static inline const char *vcol_type_name(enum_vcol_info_type type)
 #define VCOL_AUTO_INC         16
 #define VCOL_IMPOSSIBLE       32
 #define VCOL_NOT_VIRTUAL      64  /* Function can't be virtual */
+#define VCOL_CHECK_CONSTRAINT_IF_NOT_EXISTS 128
 
 #define VCOL_NOT_STRICTLY_DETERMINISTIC                       \
   (VCOL_NON_DETERMINISTIC | VCOL_TIME_FUNC | VCOL_SESSION_FUNC)
@@ -5719,7 +5720,7 @@ int set_field_to_null(Field *field);
 int set_field_to_null_with_conversions(Field *field, bool no_conversions);
 int convert_null_to_field_value_or_error(Field *field);
 bool check_expression(Virtual_column_info *vcol, const LEX_CSTRING *name,
-                      enum_vcol_info_type type);
+                      enum_vcol_info_type type, Alter_info *alter_info= NULL);
 
 /*
   The following are for the interface with the .frm file

sql/item.cc

@@ -1493,6 +1493,37 @@ bool mark_unsupported_function(const char *w1, const char *w2,
 }
 
 
+bool Item_field::check_vcol_func_processor(void *arg)
+{
+  context= 0;
+  vcol_func_processor_result *res= (vcol_func_processor_result *) arg;
+  if (res && res->alter_info)
+  {
+    for (Key &k: res->alter_info->key_list)
+    {
+      if (k.type != Key::FOREIGN_KEY)
+        continue;
+      Foreign_key *fk= (Foreign_key*) &k;
+      if (fk->update_opt != FK_OPTION_CASCADE)
+        continue;
+      for (Key_part_spec& kp: fk->columns)
+      {
+        if (!lex_string_cmp(system_charset_info, &kp.field_name, &field_name))
+        {
+          return mark_unsupported_function(field_name.str, arg, VCOL_IMPOSSIBLE);
+        }
+      }
+    }
+  }
+  if (field && (field->unireg_check == Field::NEXT_NUMBER))
+  {
+    // Auto increment fields are unsupported
+    return mark_unsupported_function(field_name.str, arg, VCOL_FIELD_REF | VCOL_AUTO_INC);
+  }
+  return mark_unsupported_function(field_name.str, arg, VCOL_FIELD_REF);
+}
+
+
 Query_fragment::Query_fragment(THD *thd, sp_head *sphead,
                                const char *start, const char *end)
 {

sql/item.h

@@ -2056,6 +2056,9 @@ class Item: public Value_source,
   {
     uint errors;                                /* Bits of possible errors */
     const char *name;                           /* Not supported function */
+    Alter_info *alter_info;
+    vcol_func_processor_result() :
+      errors(0), name(NULL), alter_info(NULL) {}
   };
   struct func_processor_rename
   {
@@ -3506,16 +3509,7 @@ class Item_field :public Item_ident,
   bool switch_to_nullable_fields_processor(void *arg);
   bool update_vcol_processor(void *arg);
   bool rename_fields_processor(void *arg);
-  bool check_vcol_func_processor(void *arg)
-  {
-    context= 0;
-    if (field && (field->unireg_check == Field::NEXT_NUMBER))
-    {
-      // Auto increment fields are unsupported
-      return mark_unsupported_function(field_name.str, arg, VCOL_FIELD_REF | VCOL_AUTO_INC);
-    }
-    return mark_unsupported_function(field_name.str, arg, VCOL_FIELD_REF);
-  }
+  bool check_vcol_func_processor(void *arg);
   bool set_fields_as_dependent_processor(void *arg)
   {
     if (!(used_tables() & OUTER_REF_TABLE_BIT))
@@ -6070,7 +6064,7 @@ class Item_copy :public Item,
   table_map used_tables() const { return (table_map) 1L; }
   bool const_item() const { return 0; }
   bool is_null() { return null_value; }
-  bool check_vcol_func_processor(void *arg) 
+  bool check_vcol_func_processor(void *arg)
   {
     return mark_unsupported_function("copy", arg, VCOL_IMPOSSIBLE);
   }

sql/sql_alter.h

@@ -95,11 +95,6 @@ class Alter_info
   List<Alter_rename_key>        alter_rename_key_list;
   // List of columns, used by both CREATE and ALTER TABLE.
   List<Create_field>            create_list;
-
-  enum flags_bits
-  {
-    CHECK_CONSTRAINT_IF_NOT_EXISTS= 1
-  };
   List<Virtual_column_info>     check_constraint_list;
   // Type of ALTER TABLE operation.
   alter_table_operations        flags;

sql/sql_lex.h

@@ -4331,8 +4331,7 @@ struct LEX: public Query_tables_list
                       bool if_not_exists)
   {
     constr->name= name;
-    constr->flags= if_not_exists ?
-                   Alter_info::CHECK_CONSTRAINT_IF_NOT_EXISTS : 0;
+    constr->flags= if_not_exists ? VCOL_CHECK_CONSTRAINT_IF_NOT_EXISTS : 0;
     alter_info.check_constraint_list.push_back(constr);
     return false;
   }

sql/sql_table.cc

@@ -4292,9 +4292,31 @@ mysql_prepare_create_table(THD *thd, HA_CREATE_INFO *create_info,
           key_info->algorithm == HA_KEY_ALG_LONG_HASH)
 
       {
+without_overlaps_err:
         my_error(ER_KEY_CANT_HAVE_WITHOUT_OVERLAPS, MYF(0), key_info->name.str);
         DBUG_RETURN(true);
       }
+      key_iterator2.rewind();
+      while ((key2 = key_iterator2++))
+      {
+        if (key2->type != Key::FOREIGN_KEY)
+          continue;
+        DBUG_ASSERT(key != key2);
+        Foreign_key *fk= (Foreign_key*) key2;
+        if (fk->update_opt != FK_OPTION_CASCADE)
+          continue;
+        for (Key_part_spec& kp: key->columns)
+        {
+          for (Key_part_spec& kp2: fk->columns)
+          {
+            if (!lex_string_cmp(system_charset_info, &kp.field_name,
+                               &kp2.field_name))
+            {
+              goto without_overlaps_err;
+            }
+          }
+        }
+      }
       create_info->period_info.unique_keys++;
     }
 
@@ -4383,7 +4405,11 @@ mysql_prepare_create_table(THD *thd, HA_CREATE_INFO *create_info,
     while ((check= c_it++))
     {
       if (!check->name.length || check->automatic_name)
+      {
+        if (check_expression(check, &check->name, VCOL_CHECK_TABLE, alter_info))
+          DBUG_RETURN(TRUE);
         continue;
+      }
 
       {
         /* Check that there's no repeating table CHECK constraint names. */
@@ -5538,7 +5564,7 @@ static bool make_unique_constraint_name(THD *thd, LEX_CSTRING *name,
     if (!check)                                 // Found unique name
     {
       name->length= (size_t) (real_end - buff);
-      name->str= thd->strmake(buff, name->length);
+      name->str= strmake_root(thd->stmt_arena->mem_root, buff, name->length);
       return (name->str == NULL);
     }
   }
@@ -6666,7 +6692,7 @@ handle_if_exists_options(THD *thd, TABLE *table, Alter_info *alter_info,
 
     while ((check=it++))
     {
-      if (!(check->flags & Alter_info::CHECK_CONSTRAINT_IF_NOT_EXISTS) &&
+      if (!(check->flags & VCOL_CHECK_CONSTRAINT_IF_NOT_EXISTS) &&
           check->name.length)
         continue;
       check->flags= 0;

sql/table.cc

@@ -3574,7 +3574,6 @@ static bool fix_and_check_vcol_expr(THD *thd, TABLE *table,
     to be part of the virtual column
   */
   Item::vcol_func_processor_result res;
-  res.errors= 0;
 
   int error= func_expr->walk(&Item::check_vcol_func_processor, 0, &res);
   if (unlikely(error || (res.errors & VCOL_IMPOSSIBLE)))