On 17.07.18 00:04, Jerry Jelinek wrote: > There have been quite a few comments since last week, so at this point I > am uncertain how to proceed with this change. I don't think I saw > anything concrete in the recent emails that I can act upon.
The outcome of this could be multiple orthogonal patches that affect the WAL file allocation behavior somehow. I think your original idea of skipping recycling on a COW file system is sound. But I would rather frame the option as "preallocating files is obviously useless on a COW file system" rather than "this will make things mysteriously faster with uncertain trade-offs". The actual implementation could use another round of consideration. I wonder how this should interact with min_wal_size. Wouldn't min_wal_size = 0 already do what we need (if you could set it to 0, which is currently not possible)? Should the new setting be something like min_wal_size = -1? Or even if it's a new setting, it might be better to act on it in XLOGfileslop(), so these things are kept closer together. -- Peter Eisentraut http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
