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InnoDB: Prevent ALTER TABLE ... ENGINE=...

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if there are foreign key constraints on the table. (Bug #5574)


sql/ha_innodb.cc:
  Add method can_switch_engines()
sql/ha_innodb.h:
  Add method can_switch_engines()
sql/handler.h:
  Add method can_switch_engines()
sql/sql_table.cc:
  Check handler::can_switch_engines() before switching storage engines
This commit is contained in:
unknown
2005-04-07 12:16:41 +03:00
parent 0d17aea729
commit f7356d7391
4 changed files with 33 additions and 0 deletions
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26
sql/ha_innodb.cc
View File

@ -4789,6 +4789,32 @@ ha_innobase::get_foreign_key_create_info(void)
return(str); return(str);
} }
/*********************************************************************
Checks if ALTER TABLE may change the storage engine of the table.
Changing storage engines is not allowed for tables for which there
are foreign key constraints (parent or child tables). */
bool
ha_innobase::can_switch_engines(void)
/*=================================*/
{
row_prebuilt_t* prebuilt = (row_prebuilt_t*) innobase_prebuilt;
bool can_switch;
DBUG_ENTER("ha_innobase::can_switch_engines");
prebuilt->trx->op_info =
"determining if there are foreign key constraints";
row_mysql_lock_data_dictionary(prebuilt->trx);
can_switch = !UT_LIST_GET_FIRST(prebuilt->table->referenced_list)
&& !UT_LIST_GET_FIRST(prebuilt->table->foreign_list);
row_mysql_unlock_data_dictionary(prebuilt->trx);
prebuilt->trx->op_info = "";
DBUG_RETURN(can_switch);
}
/*********************************************************************** /***********************************************************************
Checks if a table is referenced by a foreign key. The MySQL manual states that Checks if a table is referenced by a foreign key. The MySQL manual states that
a REPLACE is either equivalent to an INSERT, or DELETE(s) + INSERT. Only a a REPLACE is either equivalent to an INSERT, or DELETE(s) + INSERT. Only a

1
sql/ha_innodb.h
View File

@ -161,6 +161,7 @@ class ha_innobase: public handler
int check(THD* thd, HA_CHECK_OPT* check_opt); int check(THD* thd, HA_CHECK_OPT* check_opt);
char* update_table_comment(const char* comment); char* update_table_comment(const char* comment);
char* get_foreign_key_create_info(); char* get_foreign_key_create_info();
bool can_switch_engines();
uint referenced_by_foreign_key(); uint referenced_by_foreign_key();
void free_foreign_key_create_info(char* str); void free_foreign_key_create_info(char* str);
THR_LOCK_DATA **store_lock(THD *thd, THR_LOCK_DATA **to, THR_LOCK_DATA **store_lock(THD *thd, THR_LOCK_DATA **to,

2
sql/handler.h
View File

@ -450,6 +450,8 @@ public:
virtual void append_create_info(String *packet) {} virtual void append_create_info(String *packet) {}
virtual char* get_foreign_key_create_info() virtual char* get_foreign_key_create_info()
{ return(NULL);} /* gets foreign key create string from InnoDB */ { return(NULL);} /* gets foreign key create string from InnoDB */
/* used in ALTER TABLE; 1 if changing storage engine is allowed */
virtual bool can_switch_engines() { return 1; }
/* used in REPLACE; is > 0 if table is referred by a FOREIGN KEY */ /* used in REPLACE; is > 0 if table is referred by a FOREIGN KEY */
virtual uint referenced_by_foreign_key() { return 0;} virtual uint referenced_by_foreign_key() { return 0;}
virtual void init_table_handle_for_HANDLER() virtual void init_table_handle_for_HANDLER()

4
sql/sql_table.cc
View File

@ -3109,6 +3109,10 @@ int mysql_alter_table(THD *thd,char *new_db, char *new_name,
/* Safety fix for innodb */ /* Safety fix for innodb */
if (lower_case_table_names) if (lower_case_table_names)
my_casedn_str(files_charset_info, tmp_name); my_casedn_str(files_charset_info, tmp_name);
if (new_db_type != old_db_type && !table->file->can_switch_engines()) {
my_error(ER_ROW_IS_REFERENCED, MYF(0));
goto err;
}
create_info->db_type=new_db_type; create_info->db_type=new_db_type;
if (!create_info->comment) if (!create_info->comment)
create_info->comment=table->comment; create_info->comment=table->comment;