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gh-ost is reporting wrong the number of multi-columns FK  #1328

@abonacin

Description

@abonacin

gh-ost is reporting:
ERROR Found 2 parent-side foreign keys on employees.countries. Parent-side foreign keys are not supported. Bailing out

mysql> SELECT SUM(REFERENCED_TABLE_NAME IS NOT NULL AND TABLE_SCHEMA='employees' AND TABLE_NAME='countries') as num_child_side_fk,
    ->        SUM(REFERENCED_TABLE_NAME IS NOT NULL AND REFERENCED_TABLE_SCHEMA='employees' AND REFERENCED_TABLE_NAME='countries') as num_parent_side_fk
    -> FROM   INFORMATION_SCHEMA.KEY_COLUMN_USAGE
    -> WHERE  REFERENCED_TABLE_NAME IS NOT NULL
    -> AND    ((TABLE_SCHEMA='employees' AND TABLE_NAME='countries') OR (REFERENCED_TABLE_SCHEMA='employees' AND REFERENCED_TABLE_NAME='countries'));
+-------------------+--------------------+
| num_child_side_fk | num_parent_side_fk |
+-------------------+--------------------+
|                 0 |                  2 |
+-------------------+--------------------+
1 row in set (0.00 sec)

But it is a 2-columns FK

mysql> SELECT refcons.constraint_schema,
    ->        refcons.table_name,
    ->        refcons.referenced_table_name,
    ->        refcons.constraint_name,
    ->        keycol.column_name
    -> FROM   information_schema.referential_constraints refcons
    -> JOIN   information_schema.key_column_usage keycol
    -> ON     refcons.constraint_schema = keycol.table_schema
    -> AND    refcons.table_name = keycol.table_name
    -> AND    refcons.constraint_name = keycol.constraint_name
    -> WHERE  refcons.constraint_schema = 'employees'
    -> AND    refcons.referenced_table_name = 'countries';
+-------------------+------------+-----------------------+-----------------+-------------+
| CONSTRAINT_SCHEMA | TABLE_NAME | REFERENCED_TABLE_NAME | CONSTRAINT_NAME | COLUMN_NAME |
+-------------------+------------+-----------------------+-----------------+-------------+
| employees         | cities     | countries             | cit_count_fk    | country_id  |
| employees         | cities     | countries             | cit_count_fk    | cod_empresa |
+-------------------+------------+-----------------------+-----------------+-------------+
2 rows in set (0.00 sec)

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