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MDEV-28340 Don't try to create temptables in system DBs, support table_type='SYSTEM VIEW'

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This commit is contained in:
Federico Razzoli
2021-04-26 23:56:13 +01:00
committed by Vladislav Vaintroub
parent 3fe656e629
commit 489011dd0f
1 changed files with 36 additions and 18 deletions
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54
scripts/sys_schema/procedures/table_exists.sql
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@ -19,7 +19,7 @@ DELIMITER $$
CREATE DEFINER='mariadb.sys'@'localhost' PROCEDURE table_exists (
IN in_db VARCHAR(64), IN in_table VARCHAR(64),
OUT out_exists ENUM('', 'BASE TABLE', 'VIEW', 'TEMPORARY', 'SEQUENCE')
OUT out_exists ENUM('', 'BASE TABLE', 'VIEW', 'TEMPORARY', 'SEQUENCE', 'SYSTEM VIEW')
)
COMMENT '
Description
@ -41,11 +41,12 @@ CREATE DEFINER='mariadb.sys'@'localhost' PROCEDURE table_exists (
out_exists ENUM('''', ''BASE TABLE'', ''VIEW'', ''TEMPORARY''):
The return value: whether the table exists. The value is one of:
* '''' - the table does not exist neither as a base table, view, sequence nor temporary table.
* ''BASE TABLE'' - the table name exists as a permanent base table table.
* ''VIEW'' - the table name exists as a view.
* ''TEMPORARY'' - the table name exists as a temporary table.
* ''SEQUENCE'' - the table name exists as a sequence.
* '''' - the table does not exist neither as a base table, view, sequence nor temporary table.
* ''BASE TABLE'' - the table name exists as a permanent base table table.
* ''VIEW'' - the table name exists as a view.
* ''TEMPORARY'' - the table name exists as a temporary table.
* ''SEQUENCE'' - the table name exists as a sequence.
* ''SYSTEM VIEW'' - the table name exists as a system view.
Example
--------
@ -107,6 +108,16 @@ CREATE DEFINER='mariadb.sys'@'localhost' PROCEDURE table_exists (
+----------+
1 row in set (0.000 sec)
MariaDB [sys]> CALL table_exists(''information_schema'', ''user_variables'', @exists); SELECT @exists;
Query OK, 0 rows affected (0.003 sec)
+-------------+
| @exists |
+-------------+
| SYSTEM VIEW |
+-------------+
1 row in set (0.001 sec)
mysql> CALL sys.table_exists(''db1'', ''t3'', @exists); SELECT @exists;
Query OK, 0 rows affected (0.01 sec)
@ -123,6 +134,8 @@ CREATE DEFINER='mariadb.sys'@'localhost' PROCEDURE table_exists (
BEGIN
DECLARE v_error BOOLEAN DEFAULT FALSE;
DECLARE v_table_type VARCHAR(16) DEFAULT '';
DECLARE v_system_db BOOLEAN
DEFAULT LOWER(in_db) IN ('information_schema', 'performance_schema');
DECLARE CONTINUE HANDLER FOR 1050 SET v_error = TRUE;
DECLARE CONTINUE HANDLER FOR 1146 SET v_error = TRUE;
@ -132,18 +145,21 @@ BEGIN
IF (EXISTS(SELECT 1 FROM information_schema.TABLES WHERE TABLE_SCHEMA = in_db AND TABLE_NAME = in_table)) THEN
-- Unfortunately the only way to determine whether there is also a temporary table is to try to create
-- a temporary table with the same name. If it succeeds the table didn't exist as a temporary table.
SET @sys.tmp.table_exists.SQL = CONCAT('CREATE TEMPORARY TABLE `', in_db, '`.`', in_table, '` (id INT PRIMARY KEY)');
PREPARE stmt_create_table FROM @sys.tmp.table_exists.SQL;
EXECUTE stmt_create_table;
DEALLOCATE PREPARE stmt_create_table;
IF (v_error) THEN
SET out_exists = 'TEMPORARY';
ELSE
IF v_system_db = FALSE THEN
SET @sys.tmp.table_exists.SQL = CONCAT('CREATE TEMPORARY TABLE `', in_db, '`.`', in_table, '` (id INT PRIMARY KEY)');
PREPARE stmt_create_table FROM @sys.tmp.table_exists.SQL;
EXECUTE stmt_create_table;
DEALLOCATE PREPARE stmt_create_table;
-- The temporary table was created, i.e. it didn't exist. Remove it again so we don't leave garbage around.
SET @sys.tmp.table_exists.SQL = CONCAT('DROP TEMPORARY TABLE `', in_db, '`.`', in_table, '`');
PREPARE stmt_drop_table FROM @sys.tmp.table_exists.SQL;
EXECUTE stmt_drop_table;
DEALLOCATE PREPARE stmt_drop_table;
END IF;
IF (v_error) THEN
SET out_exists = 'TEMPORARY';
ELSE
SET v_table_type = (SELECT TABLE_TYPE FROM information_schema.TABLES WHERE TABLE_SCHEMA = in_db AND TABLE_NAME = in_table);
-- Don't fail on table_type='SYSTEM VERSIONED'
-- but return 'BASE TABLE' for compatibility with existing tooling
@ -157,11 +173,13 @@ BEGIN
-- Check whether a temporary table exists with the same name.
-- If it does it's possible to SELECT from the table without causing an error.
-- If it does not exist even a PREPARE using the table will fail.
SET @sys.tmp.table_exists.SQL = CONCAT('SELECT COUNT(*) FROM `', in_db, '`.`', in_table, '`');
PREPARE stmt_select FROM @sys.tmp.table_exists.SQL;
IF (NOT v_error) THEN
DEALLOCATE PREPARE stmt_select;
SET out_exists = 'TEMPORARY';
IF v_system_db = FALSE THEN
SET @sys.tmp.table_exists.SQL = CONCAT('SELECT COUNT(*) FROM `', in_db, '`.`', in_table, '`');
PREPARE stmt_select FROM @sys.tmp.table_exists.SQL;
IF (NOT v_error) THEN
DEALLOCATE PREPARE stmt_select;
SET out_exists = 'TEMPORARY';
END IF;
END IF;
END IF;
END$$