Per Tom's suggestion on bug #15396, here's a patch to have platforms such as OSX give a more descriptive message when
rejectinga nonzero value for effective_io_concurrency.
I had to adjust the GUC's wiring in the #ifndef case so that check_effective_io_concurrency() would be called when a
nonzerovalue is supplied instead of just short-circuiting in parse_and_validate_value() when outside of [conf->min,
conf->max].
James
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James Robinson
james@jlr-photo.com
http://jlr-photo.com/