On Thu, Jul 9, 2015 at 5:36 PM, Haribabu Kommi <kommi.harib...@gmail.com> wrote: > > I will do some performance tests and send you the results.
Here are the performance results tested on my machine. Head vm patch vm+prefetch patch First vacuum 120sec <1sec <1sec second vacuum 180 sec 180 sec 30 sec I did some modifications in the code to skip the vacuum truncation by the first vacuum command. This way I collected the second vacuum time taken performance. I just combined your vm and prefetch patch into a single patch vm+prefetch patch without a GUC. I kept the prefetch as 32 and did the performance test. I chosen prefetch based on the current buffer access strategy, which is 32 for vacuum presently instead of an user option. Here I attached the modified patch with both vm+prefetch logic. I will do some tests on a machine with SSD and let you know the results. Based on these results, we can decide whether we need a GUC or not? based on the impact of prefetch on ssd machines. Regards, Hari Babu Fujitsu Australia
vac_trunc_trust_vm_and_prefetch.patch
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