Re: patch to allow disable of WAL recycling

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/

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