Re: TPC-A and -B Benchmarks

In <2450@coyote.UUCP> gainer@slowmo.almaden.ibm.com (P. Gainer) writes: >In a recent append, obelix.informix.com!johnl@emory.mathcs.emory.edu (Jonathan Leffler) writes... >>The whole point of setting the isolation level to repeatable read is to >>command to the database system to ensure that any modification on any >>table which triggers a modification on any of the data read by TX1 is >>disallowed, because TX1 has demanded repeatable read isolation. If this >>is not enforced, then what you have is not repeatable read as I >>understand it. >> >>The issue rapidly reduces to: what does who mean by repeatable read. >>Oracle supplies one definition; Informix supplies another; I can't I disagree with Jonathan here. In the context of a TPC benchmark the *only* definition that has any value is that of the TPC (which I assume is derived from that of the ANSI standards committees). >And herein lies the crux of my question. It sounds to me (someone totally >ignorant about Oracle 7) that Oracle 7 will have a hard time running >the TPC-C benchmark because of its Repeatable Read implementation. >Will it not have to obtain table locks on tables it modifies, to >correctly implement the TPC-C benchmark? That is my current understanding. >If this statement is true (and it very well might not be - I hope for >corrections) then Oracle 7 would probably be at a great disadvantage >when competing with Informix and others who do have Repeatable Read >implemented with row locking, on the TPC-C benchmark. Their concurrency >would be low. Bear in mind that Oracle are not likely to be alone in this. OnLine will often (but not always) place table locks in order to implement Repeatable Read. I haven't yet had the time to examine the TPC-C transactions to deduce whether I would expect OnLine to lock tables or not in that particular case. graeme -- Disclaimer: The author's opinions are his own, and not necessarily those of Pyramid Technology Ltd. or Pyramid Technology Inc. --------------------------------------------------------------------------- -m------- Graeme Sargent Voice: +44 (0)252 373035 ---mmm----- Senior Database Consultant Fax : +44 (0)252 373135 -----mmmmm--- Pyramid Technology Ltd. Telex: Tell who??? -------mmmmmmm- Farnborough, Hants GU14 7PL Email: graeme@pyra.co.uk --------------------------------------------------------------------------- We have the technology. The tricky bit is learning how to use it.