On 2020-Jul-30, Peter Geoghegan wrote: > Commit 896ddf9b added prefetching to logtape.c to avoid excessive > fragmentation in the context of hash aggs that spill and have many > batches/tapes. Apparently the preallocation doesn't actually perform > any filesystem operations, so the new mechanism should be zero > overhead when "preallocated" blocks aren't actually used after all > (right?). However, I notice that this breaks the statistics shown by > things like trace_sort, and even EXPLAIN ANALYZE. > LogicalTapeSetBlocks() didn't get the memo about preallocation.
This open item hasn't received any replies. I think Peter knows how to fix it already, but no patch has been posted ... It'd be good to get a move on it. -- Álvaro Herrera https://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
