SE + machine crash

Greg Bryan (gbryan@ssf-sys.dhl.com) writes: > More sophisticated relational database managers ( such as Informix > Online - but NOT Informix Standard Engine ) guarantee that logical > groups of physical disk operations are handled in an all or nothing > fashion. This is done by means of logs (like the Online Physical > Log) automatic checkpoint procedures and automatic recovery procedures > (like the Online Fast Recovery) that are invoked whenever the database > manager starts up. Tony Heskett: Okay, so if it goes all the way thru, the checks on status are perfectly satisfactory, but if I flick the juice off half way thru one of the DELETEs the DB's trashed ? At that point, can one restore the backup and do a rollforward, or does one lose the log as well ? My understanding is the log isn't written synchronously. So it looks like the SE is totally vulnerable to machine interruptions. You would need to write your own log synchronously & figure out how to use it. Even if a transaction completed, if the disk hasn't been flushed by the system & the machine crashes, you're sunk. I would vote for having the SE write the log synchronously, but I hear Informix has told us that the transaction logs aren't for data security. Bill Ross