Re: CPU costs of random_zipfian in pgbench

Hello again,

>> I started to look through this, and the more I looked the more unhappy
>> I got that we're having this discussion at all. The zipfian support
>> in pgbench is seriously over-engineered and under-documented. As an
>> example, I was flabbergasted to find out that the end-of-run summary
>> statistics now include this:
>>
>> /* Report zipfian cache overflow */
>> for (i = 0; i < nthreads; i++)
>> {
>> totalCacheOverflows += threads[i].zipf_cache.overflowCount;
>> }
>> if (totalCacheOverflows > 0)
>> {
>> printf("zipfian cache array overflowed %d time(s)\n",
>> totalCacheOverflows);
>> }
>>
>> What is the point of that, and if there is a point, why is it nowhere
>> mentioned in pgbench.sgml?

The attached patch simplifies the code by erroring on cache overflow,
instead of the LRU replacement strategy and unhelpful final report. The
above lines are removed.

--
Fabien.