Hi,
I wonder if we can collect some stats to measure how effective the
prefetching actually is. Ultimately we want something like cache hit
ratio, but we're only preloading into page cache, so we can't easily
measure that. Perhaps we could measure I/O timings in redo, though?
regards
--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services