Re: Running tally

You can use plpythonu (or tcl or C or R) to do running
sums. For plpythonu, you must initialize the SD[]
by calling it first with the proper argument.

create or replace function runsum(int,int)
returns int as
'
if args[0] == 1:
SD["currval"] = 0
return SD["currval"]
else:
try:
SD["currval"] += args[1]
except:
SD["currval"] = args[1]
return SD["currval"]
' language 'plpython';

select runsum(1,0);
select num, runsum(0,num) from tallytable;

Variations on this technique are discussed on
General Bits http://www.varlena.com/GeneralBits
under the Tidbits area listing talks from OSCON2003.

elein(at)varlena(dot)com

webstat=# select runsum(0,code), code, doc from temp_rawlogs;
n Sat, Oct 04, 2003 at 05:56:38PM +0800, Christopher Kings-Lynne wrote:
> Hi guys,
>
> If I have a table that is just a single column full of numbers, how can
> I select all the rows from the table with a second column that is the
> running tally so far down the result set?
>
> eg:
>
> Num Tally so far
> 0.3 0.3
> 1.2 1.5
> 2.0 3.5
> ...
>
> Does this require PL/PgSQL coding? If so, how do you actually construct
> an arbitrary row for returning? The docs are somewhat unclear on this.
>
> Chris
>
>
>
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