Re: custom function for converting human readable sizes to bytes

Hello, The meaning of "be orange" (I couldn't find it) interests
me but putting it aside..

I have some random comments.

At Mon, 30 Nov 2015 18:30:18 +0100, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote in <CAFj8pRCd6We3TQMR0VbCN98wF0P3O3H6NaU4BTaosWcj443Qjw(at)mail(dot)gmail(dot)com>
> Hi
>
>
> > 2. using independent implementation - there is some redundant code, but we
> > can support duble insted int, and we can support some additional units.
> >
>
> new patch is based on own implementation - use numeric/bigint calculations
>
> + regress tests and doc

1. What do you think about binary byte prefixes? (kiB, MiB...)

I couldn't read what Robert wrote upthread but I also would like
to have 2-base byte unit prifixes. (Sorry I couldn't put it
aside..)

2. Doesn't it allow units in lower case?

I think '1gb' and so should be acceptable as an input.

3. Why are you allow positive sign prefixing digits? I suppose
that positive sign also shouldn't be allowed if it rejects
prifixing negative sign.

4. Useless includes

dbsize.c is modified to include guc.h but it is useless.

5. Error message

+ if (ndigits == 0)
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("string is empty")));

If pg_size_bytes allows prefixing positive sign or spaces,
ndigits == 0 here doesn't mean that the whole string is empty.

6. Symmetry with pg_size_pretty

pg_size_pretty doesn't have units larger than TB. Just adding PB
to it breaks backward compatibility, but leaving as it is breaks
symmetry with this function. Some possible solution for this
that I can guess for now are..

- Leave it as is.

- New GUC to allow PB for pg_size_pretty().

- Expanded function such like pg_size_pretty2 (oops..)

- New polymorphic (sibling?) function with additional
parameters to instruct how they work. (The following
involving 2-base representations)

pg_size_pretty(n, <2base>, <allow_PB or such..>);
pg_size_bytes(n, <2base>, <allow_PB or such..>);

7. Docs

+ Converts a size in human-readable format with size units
+ to bytes

The descriptions for the functions around use 'into' instead of
'to' for the preposition.

8. Regression

The regression in the patch looks good enough as is (except that
it forgets the unit 'B' or prifixing spaces or sings), but they
are necessarily have individual tests. The following SQL
statement will do them at once.

SELECT s, pg_size_bytes(s) FROM (VALUES ('1'), ('1B')...) as t(s);

regards,

--
Kyotaro Horiguchi
NTT Open Source Software Center