Re: Maximum update frequency.

Juan Pardillos wrote:
> I'd like to know which is the maximum update frequency

Database performance is measured by benchmarks. You get to decide whether the benchmark transactions resemble your task, but the relevant industry benchmarks are TPA, TPB and TPC.

TPA is a simple debit/credit transaction with 100-byte message input, four database updates, a 200-byte message output (the communications are included in the cost). The operations are a mix of main-memory, random and sequention accesses. Before TPA was introduced, DBMS products varied widely in their performance. Within a year or two, they'd all been optimised down to somewhere in the vicinity of 100,000 machine instructions and 2.1 real disk writes per (TPA) transaction. (From Gray&Reuter: Transaction Processing; concepts and techniques 1990).

Since then, CPU instruction speed has outstripped main-memory speed, so that bandwidth, not MIPs, has become the issue, but even that's still moot since disk performance hasn't jumped by more than an order of magnitude.

TPC is the current standard, it defines a transaction load about ten times more complex than TPA. For more details on DBMS benchmarking, go to www.tpc.org, they define the standards. The end result of benchmarking is a cost measured in dollars per TPS (transaction-per-second).

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Clifford Heath