Re: Adding unsigned 256 bit integers

Thanks for helping me out everyone. I ended up simply using the numeric
type (I didn't realize it could support such large numbers) and writing the
hex-to-numeric conversion functions in my application code.

On 11 April 2014 12:27, Leon Smith <leon(dot)p(dot)smith(at)gmail(dot)com> wrote:

> pgmp is also worth mentioning here, and it's likely to be more efficient
> than the numeric type or something you hack up yourself:
>
> http://pgmp.projects.pgfoundry.org/
>
> Best,
> Leon
>
>
> On Thu, Apr 10, 2014 at 10:11 AM, ktm(at)rice(dot)edu <ktm(at)rice(dot)edu> wrote:
>
>> On Thu, Apr 10, 2014 at 09:13:47PM +0800, Olivier Lalonde wrote:
>> > I was wondering if there would be any way to do the following in
>> PostgreSQL:
>> >
>> > UPDATE cryptotable SET work = work + 'some big hexadecimal number'
>> >
>> > where work is an unsigned 256 bit integer. Right now my column is a
>> > character varying(64) column (hexadecimal representation of the number)
>> but
>> > I would be happy to switch to another data type if it lets me do the
>> > operation above.
>> >
>> > If it's not possible with vanilla PostgreSQL, are there extensions that
>> > could help me?
>> >
>> > --
>> > - Oli
>> >
>> > Olivier Lalonde
>> > http://www.syskall.com <-- connect with me!
>> >
>>
>> Hi Olivier,
>>
>> Here are some sample pl/pgsql helper functions that I have written for
>> other purposes. They use integers but can be adapted to use numeric.
>>
>> Regards,
>> Ken
>> ---------------------------
>> CREATE OR REPLACE FUNCTION hex2dec(t text) RETURNS integer AS $$
>> DECLARE
>> r RECORD;
>> BEGIN
>> FOR r IN EXECUTE 'SELECT x'''||t||'''::integer AS hex' LOOP
>> RETURN r.hex;
>> END LOOP;
>> END
>> $$ LANGUAGE plpgsql IMMUTABLE STRICT;
>> ---------------------------
>>
>> ---------------------------
>> CREATE OR REPLACE FUNCTION bytea2int (
>> in_string BYTEA
>> ) RETURNS INTEGER AS $$
>>
>> DECLARE
>>
>> b1 INTEGER := 0;
>> b2 INTEGER := 0;
>> b3 INTEGER := 0;
>> b4 INTEGER := 0;
>> out_int INTEGER := 0;
>>
>> BEGIN
>>
>> CASE OCTET_LENGTH(in_string)
>> WHEN 1 THEN
>> b4 := get_byte(in_string, 0);
>> WHEN 2 THEN
>> b3 := get_byte(in_string, 0);
>> b4 := get_byte(in_string, 1);
>> WHEN 3 THEN
>> b2 := get_byte(in_string, 0);
>> b3 := get_byte(in_string, 1);
>> b4 := get_byte(in_string, 2);
>> WHEN 4 THEN
>> b1 := get_byte(in_string, 0);
>> b2 := get_byte(in_string, 1);
>> b3 := get_byte(in_string, 2);
>> b4 := get_byte(in_string, 3);
>> END CASE;
>>
>> out_int := (b1 << 24) + (b2 << 16) + (b3 << 8) + b4;
>>
>> RETURN(out_int);
>> END;
>> $$ LANGUAGE plpgsql IMMUTABLE;
>> ---------------------------
>>
>>
>> --
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>>
>
>

--
- Oli

Olivier Lalonde
http://www.syskall.com <-- connect with me!

Freelance web and Node.js engineer
Skype: o-lalonde