Hello.
>Does that imply that if we set this flush_time value to zero (ie no >periodic flush to disk), then some of the data will not be committed to >disk, and if we had a subsequent power failure, then any data since the >last flush would be lost? We have innodb_flush_log_at_trx_commit set to 1. MySQL will update the files on disk with system call after every SQL statement and before the client is notified about the result. (This is not true if you are running with --delay-key-write, in which case data files are written but not index files.) This means that data file contents are safe even if mysqld crashes, because the operating system will ensure that the unflushed data is written to disk. Terry Riley <[EMAIL PROTECTED]> wrote: > We're running mostly with InnoDB tables, about 5% updates/inserts/deletes, > the rest selects, on Windows NT. > > In setting table_cache to 256 from the default 64, we hoped to improve > performance a little, by not having to continually close/open tables. > > Then we noticed that the opened table count dropped to zero and began to > climb again every 30 minutes - a consequence, through later reading of the > Fine Manual, of the flush_time setting of 30 minutes (1800 sec), which > seems to be recommended for W9x and Me only. The docs state that this > action 'closes tables to flush pending changes to disk' every flush_time > seconds. > > The means (I think) that some (though I doubt all, given the size of some > tables) tables could be completely in memory. > > Does that imply that if we set this flush_time value to zero (ie no > periodic flush to disk), then some of the data will not be committed to > disk, and if we had a subsequent power failure, then any data since the > last flush would be lost? We have innodb_flush_log_at_trx_commit set to 1. > > Given the above, is it unwise to drop the periodic flush? > > The related item: > > The number of tables in all our databases, including mysql, is 130. > > What other tables are counted in the opened_tables calculation; does this > include tables that may be opened twice under different aliases? Does this > include temporary tables (created by MySQL)? > > Cheers > Terry Riley > > -- For technical support contracts, goto https://order.mysql.com/?ref=ensita This email is sponsored by Ensita.NET http://www.ensita.net/ __ ___ ___ ____ __ / |/ /_ __/ __/ __ \/ / Gleb Paharenko / /|_/ / // /\ \/ /_/ / /__ [EMAIL PROTECTED] /_/ /_/\_, /___/\___\_\___/ MySQL AB / Ensita.NET <___/ www.mysql.com -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
