VR>Date: Mon, 28 Oct 2002 12:35:01 +0200 VR>From: Victoria Reznichenko <[EMAIL PROTECTED]> VR>Subject: re: database corrupted after power switched off
VR>Tom, VR>Monday, October 28, 2002, 11:59:16 AM, you wrote: VR>TT> is it a normal behaviour that a sql databases gets corrupted if the power of VR>TT> the whole system will be switched off while an application is writing to the VR>TT> database ? VR>Yes. Other situations when tables may become corrupted are listed VR>here: VR> http://www.mysql.com/doc/en/Corrupted_MyISAM_tables.html ... which says "MyISAM table format is very reliable (all changes to a table is written before the SQL statements returns)" Evidently, this is NOT true. (Perhaps, it used to be true for ISAM tables. The documentation should be changed.) VR>TT> what can i do that this problem does no more appear ? VR>You have to shutdown MySQL server correctly, buy UPS :-) There are a couple of other choices (perhaps to be used in addition to UPS). (1) Use InnoDB tables. Evidently, they are designed to survive such things, especially with innodb_flush_log_at_trx_commit=1. We have survived having the server disconnected from the UPS. I hope to not find out if it works twice :-) (2) If you have updates in infrequent bursts, such as with a server used primarily for queries or a single-user system, do FLUSH TABLES after each burst. This writes the tables to disk. We have a number of users with single-user local database a which are synchronized with the server from time to time, and we have no control over whether or not they have UPS. We did have the problem that the databases would be corrupted if power were lost an hour after updating. Adding the FLUSH TABLES after each user interaction that updates the database solved this. (In reality, we only flush the tables that have been modified.) --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
