"Bruce Momjian" <[EMAIL PROTECTED]> writes: > Where are we on this?
Well Simon just sent the reworked patch yesterday so the answer is we haven't started tuning this parameter. (Bruce's message is referring to the discussion about what the optimal value of lsns per clog page would be.) I intend to do some benchmarking on it and testing what the best value of this parameter is one of the things I aim to determine with these benchmarks. I'm not 100% sure yet what to measure though. There are two questions here: 1) What are some good workloads to test which will require larger values for this parameter or which will be hurt by excessively large values? I think any short-transaction workload should be basically good enough. I'm thinking of using just pgbench's default workload. Does anyone think there are other workloads that we need to specifically test? 2) What metric do I use to determine if the value is large enough or too large? The gross measurement would be to look at tps. I would prefer to actually count events which we want to minimize such as xlogflushes because the clog lsn is too old and how much extra work the visibility checks do. I'm not sure exactly how much of this we can really measure though. Are there any other events having an insufficiently large or excessively large value of this parameter will cause which we can count? -- Gregory Stark EnterpriseDB http://www.enterprisedb.com ---------------------------(end of broadcast)--------------------------- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq