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MDEV-15199 Referential integrity broken in ON DELETE CASCADE

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MDEV-14222 Unnecessary 'cascade' memory allocation for every updated row
when there is no FOREIGN KEY

This reverts the MySQL 5.7.2 change
377774689b
which introduced these problems. MariaDB 10.2.2 inherited these problems
in commit 2e814d4702.

The FOREIGN KEY CASCADE and SET NULL operations implemented as
procedural recursion are consuming more than 8 kilobytes of stack
(9 stack frames) per iteration in a non-debug GNU/Linux AMD64 build.
This is why we need to limit the maximum recursion depth to 15 steps
instead of the 255 that it used to be in MySQL 5.7 and MariaDB 10.2.

A corresponding change was made in MySQL 5.7.21 in
7b26dc98a6
This commit is contained in:
Marko Mäkelä 2018-02-06 13:53:20 +02:00
commit 10590dd39c
13 changed files with 281 additions and 509 deletions
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12
storage/innobase/include/row0mysql.h
View file

@ -297,6 +297,18 @@ row_create_update_node_for_mysql(
/*=============================*/
dict_table_t* table, /*!< in: table to update */
mem_heap_t* heap); /*!< in: mem heap from which allocated */
/**********************************************************************//**
Does a cascaded delete or set null in a foreign key operation.
@return error code or DB_SUCCESS */
dberr_t
row_update_cascade_for_mysql(
/*=========================*/
que_thr_t* thr, /*!< in: query thread */
upd_node_t* node, /*!< in: update node used in the cascade
or set null operation */
dict_table_t* table) /*!< in: table where we do the operation */
MY_ATTRIBUTE((nonnull, warn_unused_result));
/*********************************************************************//**
Locks the data dictionary exclusively for performing a table create or other
data dictionary modification operation. */