Gleb ----- Original Message -----
> 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. > Thanks for that - we're not running delay-key-write, so I assume therefore that there is no harm in changing flush_time to zero. Any ideas on the second part of my question (which tables are counted)? Cheers Terry > > > 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 -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
