MySQL Bugs: #32954: Online Backup: MyISAM default driver misses rows in release build

Bug #32954	Online Backup: MyISAM default driver misses rows in release build
Submitted:	4 Dec 2007 11:29	Modified:	26 Feb 2008 1:36
Reporter:	Lars Thalmann	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: Backup	Severity:	S3 (Non-critical)
Version:	6.0	OS:	Any
Assigned to:	Chuck Bell	CPU Architecture:	Any

Description:
Repeated backups leads to lost rows using default driver for MyISAM.

How to repeat:
--source include/have_innodb.inc
--source include/not_embedded.inc

connect (backup,localhost,root,,);
connect (restore,localhost,root,,);

connection backup;

USE test;

DELETE FROM mysql.online_backup;
DELETE FROM mysql.online_backup_progress;

--disable_query_log
CREATE TABLE `building` (
  `dir_code` char(4)
)ENGINE=INNODB;
--enable_query_log

INSERT INTO `building` VALUES ('N41');

--replace_column 1 #
BACKUP DATABASE test TO 'test.ba';
SELECT total_bytes FROM mysql.online_backup;

DROP DATABASE test;

connection restore;

DELETE FROM mysql.online_backup;
DELETE FROM mysql.online_backup_progress;

--replace_column 1 #
RESTORE FROM 'test.ba';
SELECT total_bytes FROM mysql.online_backup;

USE test;

# Wait for rows to be written to table.
let $wait_condition = SELECT count(*) = 1
                      FROM test.building;
--source include/wait_condition.inc

SELECT * FROM building;

DROP TABLE IF EXISTS building;

Cannot reproduce error in test. Submitted patch to change backup.test to use MyISAM (as before when error occurred). I will monitor PB for the results.

Problem identified: The problem occurs on restore. The MyISAM records are being unpacked correctly but the record contains some invalid data. This invalid data is related to the defaults data settings. To solve the problem, a call to restore_record() must be made prior to unpacking the row data from the buffer.

Patch ready for review. See http://lists.mysql.com/commits/40046.

Good to push.

Pushed into 6.0.5-alpha

Noted in 6.0.5 changelog.

The MyISAM driver for Online Backup could incorrectly restore data.

Correction: No changelog entry needed; this bug did not appear in any released version.