Re: BUFFERED LOGGING: Is it safe??

} } I'm trying to decide whether to use buffered or unbuffered logging } for a customer's database. The engine is Online 5.02.UC6. } } The Online Administrator's Guide says that "if you use buffered logging } and a failure occurs, you could lose more than just the current } transaction. In return for this risk, performance during alterations is } slightly improved." Does this mean that buffered logging carries with it } the risk that the fast-recovery mechanism might not be able to restore the } database to a consistent state in the event of a failure, or does it merely } mean that more transactions might be rolled back than otherwise would be? } } In other words, could buffered logging compromise the integrity of the } database in the event of a failure? Buffered logging writes transaction log information to a logical log buffer, this buffer gets flushed when it gets full, this accounts for the improvement in performance. The danger comes when there is one or more committed transactions in the buffer but it is not yet full, a failure at this point means that fast recovery will not even know that these transactions ever occurred, remember they are in the buffer but not yet written to the logs on disk. The result is that you would think the transactions were successful but the system thinks they never occured therefore you lost them. If you wish to insure that committed transactions are never lost use unbuffered logging. Mike } } Thanks in advance ... } -- } ______________________________________________________________________________ } Steve Chell steve@nezsdc.fujitsu.co.nz } Fujitsu NZ Ltd, Auckland, New Zealand FAX: +64.9.3564851 }