Re: Questions about SE Transactions (& Performance)

In article <3t1dbu$kht@access5.digex.net> briang@access5.digex.net "Brian G." writes: > I am looking to add transactions to an existing production database > running on SCO SE 4.11. I hope that 4.11 refers to the 4GL/RDS/SQL version you have. If your database engine is REALLY 4.11 (use 'dbaccess -v' to find out) get an upgrade it at all possible. You should be looking for 5.02 or 5.03, I think. Also, 4GL/RDS/SQL will now be available in 4.12 or 4.13 for you box, I think. > Some questions: > > Is it possible to undo START DATABASE db WITH LOG IN "file"? This is done by updating the 'syslog' row in 'systables' so that the 'tabtype' is not 'L' (or any other value which Informix understands, so we use 'z'). You will have to 'su informix' first. > In addition, what are the performance considerations in using > transactions? All I can think of is: > > Time to write db updates to the logfile > Time to lock and unlock records in the transaction > > Any other issues I should be aware of (other than making sure the > logfile doesn't eat up all the disk space?) Temporary tables should probably be created without logging as otherwise all changes to them get logged which can be very slow. You could possible get contention without a suitable locking stratagy. You should ensure that the transaction log is on a nice fast device without any database tables, though I have found that putting it & temporary files (with DBTEMP) into the same slice is effective as it minimises head movement compared with having them on different slices on the same disc. You need to backup the whole database each night, and clear down the transaction logs afterwards. -- ============================================================================ Sally Woolrich | This mail contains my personal sally@excelsis.demon.co.uk | views not those of my employer! ============================================================================