Horton

Re: custom function for converting human readable sizes to bytes

Oleksandr Shulgin <oleksandr.shulgin@zalando.de>

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From: "Shulgin, Oleksandr" <oleksandr.shulgin@zalando.de>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Pavel Stehule <pavel.stehule@gmail.com>, Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>, Alvaro Herrera <alvherre@2ndquadrant.com>, Tom Lane <tgl@sss.pgh.pa.us>, Jim Nasby <Jim.Nasby@bluetreble.com>, Corey Huinker <corey.huinker@gmail.com>, Guillaume Lelarge <guillaume@lelarge.info>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2016-01-04T17:17:52Z
Lists: pgsql-hackers 
On Mon, Jan 4, 2016 at 6:14 PM, Robert Haas <robertmhaas@gmail.com> wrote:

> On Mon, Jan 4, 2016 at 11:48 AM, Shulgin, Oleksandr
> >
> > postgres=# select pg_size_bytes('');
> > ERROR:  invalid input syntax for type numeric: ""
>
> I think that's a pretty bad error message.  I mean, the user is
> calling a function that takes text as an input data type.  So, where's
> numeric involved?
>

Is there a way to force CONTEXT output in the reported error?  I guess that
could help.

I'm also kind of wondering what the intended use case for this
> function is.  Why do we want it?  Do we want it?
>

As suggested above a usecase could be like the following:

SELECT relname FROM pg_class WHERE pg_relation_size(oid) >
pg_size_bytes('100 GB');

I think it's neat and useful.

--
Alex

Commits

  1. Add pg_size_bytes() to parse human-readable size strings.

  2. Refactor check_functional_grouping() to use get_primary_key_attnos().

  3. Correct comment in GetConflictingVirtualXIDs()

  4. Make extract() do something more reasonable with infinite datetimes.

  5. pg_size_pretty: Format negative values similar to positive ones.

  6. pg_size_pretty(numeric)