Re: custom function for converting human readable sizes to bytes

2015-12-22 6:22 GMT+01:00 Michael Paquier <michael(dot)paquier(at)gmail(dot)com>:

> On Tue, Dec 22, 2015 at 12:11 AM, Robert Haas <robertmhaas(at)gmail(dot)com>
> wrote:
> > On Sun, Dec 20, 2015 at 4:54 AM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
> wrote:
> >> new update:
> >>
> >> 1. unit searching is case insensitive
> >>
> >> 2. initial support for binary byte prefixes - KiB, MiB, .. (IEC
> standard),
> >> change behave for SI units
> >>
> >> Second point is much more complex then it is looking - if pg_size_bytes
> >> should be consistent with pg_size_pretty.
> >>
> >> The current pg_size_pretty and transformations in guc.c are based on
> JEDEC
> >> standard. Using this standard for GUC has sense - using it for object
> sizes
> >> is probably unhappy.
> >>
> >> I tried to fix (and enhance) pg_size_pretty - now reports correct
> units, and
> >> via second parameter it allows to specify base: 2 (binary, IEC -
> default)
> >> or 10 (SI).
> >
> > -1 from me. I don't think we should muck with the way pg_size_pretty
> works.
>
> Yeah.
>
> + static const unit_multiplier unit_multiplier_table[] =
> + {
> + {"B", 1L},
> + {"kiB", 1024L},
> + {"MiB", 1024L * 1024},
> + {"GiB", 1024L * 1024 * 1024},
> + {"TiB", 1024L * 1024 * 1024 * 1024},
> + {"PiB", 1024L * 1024 * 1024 * 1024 * 1024},
> This is rather close to memory_unit_conversion_table in guc.c. Would
> it be worth refactoring those unit tables into something more generic
> instead of duplicating them?
>

yes, it is possible with following impacts:

1. We need add PB to memory_unit_conversion_table in guc.c
2. This table holds multipliers in JEDEC standard - and introduce other
standards IEC, SI there isn't good idea.

Is it ok?

Regards

Pavel

> --
> Michael
>