Hi PG devs! Tom Lane <t...@sss.pgh.pa.us> writes:
>> Wait for first IO, issue second IO request >> Compute >> Already have second IO request, issue third >> ... > >> We'd be a lot less sensitive to IO latency. > > It would take about five minutes of coding to prove or disprove this: > stick a PrefetchBuffer call into heapgetpage() to launch a request for the > next page as soon as we've read the current one, and then see if that > makes any obvious performance difference. I'm not convinced that it will, > but if it did then we could think about how to make it work for real. Sorry for dropping in so late... I have done all this two years ago. For TPC-H Q8, Q9, Q17, Q20, and Q21 I see a speedup of ~100% when using IndexScan prefetching + Nested-Loops Look-Ahead (the outer loop!). (On SSD with 32 Pages Prefetch/Look-Ahead + Cold Page Cache / Small RAM) Regards, Daniel -- MSc. Daniel Bausch Research Assistant (Computer Science) Technische Universität Darmstadt http://www.dvs.tu-darmstadt.de/staff/dbausch -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
