[mysql] collect foreign key delete and update rule (#19797)

* collect foreign key delete and update rule

* add changelog

* fix test

* fix tests fail for mariadb

* update changelog

Author: lu-zhengda

mysql/changelog.d/19797.added

@@ -0,0 +1,2 @@
+Collect MySQL foreign key delete_rule and update_rule from INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS.
+Note: On MariaDB 10.5+, REFERENCES privilege is required to access this information.

mysql/datadog_checks/mysql/databases_data.py

@@ -225,6 +225,8 @@ def _collect_databases_data(self, tags):
                             - referenced_table_schema (str): The schema of the referenced table.
                             - referenced_table_name (str): The name of the referenced table.
                             - referenced_column_names (str): The column names in the referenced table.
+                            - update_action (str): The update rule for the foreign key.
+                            - delete_action (str): The delete rule for the foreign key.
                     - partitions (list): A list of partition dictionaries.
                         - partition (dict): A dictionary representing a partition.
                             - name (str): The name of the partition.

mysql/datadog_checks/mysql/queries.py

@@ -161,19 +161,32 @@
 
 SQL_FOREIGN_KEYS = """\
 SELECT
-    constraint_schema as `constraint_schema`,
-    constraint_name as `name`,
-    table_name as `table_name`,
-    group_concat(column_name order by ordinal_position asc) as column_names,
-    referenced_table_schema as `referenced_table_schema`,
-    referenced_table_name as `referenced_table_name`,
-    group_concat(referenced_column_name) as referenced_column_names
+    kcu.constraint_schema as constraint_schema,
+    kcu.constraint_name as name,
+    kcu.table_name as table_name,
+    group_concat(kcu.column_name order by kcu.ordinal_position asc) as column_names,
+    kcu.referenced_table_schema as referenced_table_schema,
+    kcu.referenced_table_name as referenced_table_name,
+    group_concat(kcu.referenced_column_name) as referenced_column_names,
+    rc.update_rule as update_action,
+    rc.delete_rule as delete_action
 FROM
-    INFORMATION_SCHEMA.KEY_COLUMN_USAGE
+    INFORMATION_SCHEMA.KEY_COLUMN_USAGE kcu
+LEFT JOIN
+    INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS rc
+    ON kcu.CONSTRAINT_SCHEMA = rc.CONSTRAINT_SCHEMA
+    AND kcu.CONSTRAINT_NAME = rc.CONSTRAINT_NAME
 WHERE
-    table_schema = %s AND table_name in ({})
-    AND referenced_table_name is not null
-GROUP BY constraint_schema, constraint_name, table_name, referenced_table_schema, referenced_table_name;
+    kcu.table_schema = %s AND kcu.table_name in ({})
+    AND kcu.referenced_table_name is not null
+GROUP BY
+    kcu.constraint_schema,
+    kcu.constraint_name,
+    kcu.table_name,
+    kcu.referenced_table_schema,
+    kcu.referenced_table_name,
+    rc.update_rule,
+    rc.delete_rule
 """
 
 SQL_PARTITION = """\

mysql/tests/conftest.py

@@ -473,6 +473,8 @@ def add_schema_test_databases(cursor):
     cursor.execute("CREATE DATABASE datadog_test_schemas;")
     cursor.execute("USE datadog_test_schemas;")
     cursor.execute("GRANT SELECT ON datadog_test_schemas.* TO 'dog'@'%';")
+    # needed to query INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS in mariadb 10.5 and above
+    cursor.execute("GRANT REFERENCES ON datadog_test_schemas.* TO 'dog'@'%';")
     cursor.execute(
         """CREATE TABLE cities (
            id INT NOT NULL DEFAULT 0,
@@ -508,7 +510,8 @@ def add_schema_test_databases(cursor):
         """CREATE TABLE landmarks (
            name VARCHAR(255),
            city_id INT DEFAULT 0,
-           CONSTRAINT FK_CityId FOREIGN KEY (city_id) REFERENCES cities(id));
+           CONSTRAINT FK_CityId FOREIGN KEY (city_id)
+           REFERENCES cities(id) ON DELETE SET NULL ON UPDATE RESTRICT);
         """
     )
 
@@ -527,7 +530,7 @@ def add_schema_test_databases(cursor):
             District VARCHAR(255),
             Review TEXT,
             CONSTRAINT FK_RestaurantNameDistrict FOREIGN KEY (RestaurantName, District)
-            REFERENCES Restaurants(RestaurantName, District));
+            REFERENCES Restaurants(RestaurantName, District) ON DELETE CASCADE ON UPDATE NO ACTION);
         """
     )
     # Second DB

mysql/tests/test_metadata.py

@@ -156,6 +156,8 @@ def test_collect_schemas(aggregator, dd_run_check, dbm_instance):
                         "referenced_table_schema": "datadog_test_schemas",
                         "referenced_table_name": "Restaurants",
                         "referenced_column_names": "District,RestaurantName",
+                        "update_action": "NO ACTION",
+                        "delete_action": "CASCADE",
                     }
                 ],
                 "indexes": [
@@ -458,6 +460,8 @@ def test_collect_schemas(aggregator, dd_run_check, dbm_instance):
                         "referenced_table_schema": "datadog_test_schemas",
                         "referenced_table_name": "cities",
                         "referenced_column_names": "id",
+                        "update_action": "RESTRICT",
+                        "delete_action": "SET NULL",
                     }
                 ],
                 "indexes": [