Re: TPC-A and -B Benchmarks

In a recent append, gainer@almaden.ibm.com >In a recent append, alexk@infmuc.informix.com writes... >>To run TPC-C benchmarks a certain isolation level is required (as far as >>I heard). This isolation level is not yet supported by Oracle... >>Any comments on this?? >The TPC-C benchmark, as I was given to understand, runs 4 of its 5 >transactions using the Repeatable Read isolation level and the fifth >(the stocklevel transaction) using the Cursor Stability isolation level. >Repeatable Read implies row locks are held until a commit point is >encountered. I don't really know what Oracle supports as regards row >locking. Could someone from Oracle enlighten us? I know that Oracle 7 (and 6) supports repeatable read (which means one can repeatably read any row encountered in a transaction, no matter how many tables are involved in the transaction). However repeatable read is enabled in one of two ways. For all user of a database RR can be enables by specifying a parameter in the init*.ora file. However this changes locking level from Oracle's exemplary row level to an absymal table level. The other enabling technique has the same result, table level locking, although it is specified on a per transaction basis. This probably explains the lack of published benchmark results! I believe cursor stability implies the maintenance of cursor positioning across commits and/or rollbacks. Note that in some cases this could violate ANSI standards. Oracle supports the ANSI mode and (I think) a more complete implementation of cursor stability. Note that I said "I believe" at the start of this paragraph and the relevant information is book knowledge, not practical experience. Regards, Marv mrichardso@shl.com