branches/5.1:

Merge r2160 from trunk/:

Fix Bug#18942 by dropping all foreign key constraints at the end of
DROP DATABASE. Usually, by then, there are no foreign constraints
left because all of them are dropped when the relevant tables are
dropped. This code is to ensure that any orphaned FKs are wiped too.

row/row0mysql.c

@@ -3312,6 +3312,66 @@ funct_exit:
 	return((int) err);
 }
 
+/***********************************************************************
+Drop all foreign keys in a database, see Bug#18942.
+Called at the end of row_drop_database_for_mysql(). */
+static
+ulint
+drop_all_foreign_keys_in_db(
+/*========================*/
+				/* out: error code or DB_SUCCESS */
+	const char*	name,	/* in: database name which ends to '/' */
+	trx_t*		trx)	/* in: transaction handle */
+{
+	pars_info_t*	pinfo;
+	ulint		err;
+
+	ut_a(name[strlen(name) - 1] == '/');
+
+	pinfo = pars_info_create();
+
+	pars_info_add_str_literal(pinfo, "dbname", name);
+
+/* true if for_name is not prefixed with dbname */
+#define TABLE_NOT_IN_THIS_DB \
+"SUBSTR(for_name, 0, LENGTH(:dbname)) <> :dbname"
+
+	err = que_eval_sql(pinfo,
+			   "PROCEDURE DROP_ALL_FOREIGN_KEYS_PROC () IS\n"
+			   "foreign_id CHAR;\n"
+			   "for_name CHAR;\n"
+			   "found INT;\n"
+			   "DECLARE CURSOR cur IS\n"
+			   "SELECT ID, FOR_NAME FROM SYS_FOREIGN\n"
+			   "WHERE FOR_NAME >= :dbname\n"
+			   "LOCK IN SHARE MODE\n"
+			   "ORDER BY FOR_NAME;\n"
+			   "BEGIN\n"
+			   "found := 1;\n"
+			   "OPEN cur;\n"
+			   "WHILE found = 1 LOOP\n"
+			   "        FETCH cur INTO foreign_id, for_name;\n"
+			   "        IF (SQL % NOTFOUND) THEN\n"
+			   "                found := 0;\n"
+			   "        ELSIF (" TABLE_NOT_IN_THIS_DB ") THEN\n"
+			   "                found := 0;\n"
+			   "        ELSIF (1=1) THEN\n"
+			   "                DELETE FROM SYS_FOREIGN_COLS\n"
+			   "                WHERE ID = foreign_id;\n"
+			   "                DELETE FROM SYS_FOREIGN\n"
+			   "                WHERE ID = foreign_id;\n"
+			   "        END IF;\n"
+			   "END LOOP;\n"
+			   "CLOSE cur;\n"
+			   "COMMIT WORK;\n"
+			   "END;\n",
+			   FALSE, /* do not reserve dict mutex,
+				  we are already holding it */
+			   trx);
+
+	return(err);
+}
+
 /*************************************************************************
 Drops a database for MySQL. */
 
@@ -3382,6 +3442,19 @@ loop:
 		}
 	}
 
+	if (err == DB_SUCCESS) {
+		/* after dropping all tables try to drop all leftover
+		foreign keys in case orphaned ones exist */
+		err = (int) drop_all_foreign_keys_in_db(name, trx);
+
+		if (err != DB_SUCCESS) {
+			fputs("InnoDB: DROP DATABASE ", stderr);
+			ut_print_name(stderr, trx, TRUE, name);
+			fprintf(stderr, " failed with error %d while "
+				"dropping all foreign keys", err);
+		}
+	}
+
 	trx_commit_for_mysql(trx);
 
 	row_mysql_unlock_data_dictionary(trx);