POWER vs. POW ???

On Thu, Nov 24, 2005 at 08:00:21PM +0800, Christopher Kings-Lynne wrote:

How come these give slightly different results?

test=# SELECT POW(2,-2);
pow
------
0.25
(1 row)

test=# SELECT POWER(2,-2);
power
-------
0.25
(1 row)

(Note width of result field.)

The result field is the length of min(the string, printable result) + 2:

# SELECT POW(2,-2);
pow
------
0.25
(1 row)

# SELECT POW(2,-2) as power;
power
-------
0.25
(1 row)

# SELECT POW(2,-2) as p;
p
------
0.25
(1 row)

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__________________________________________________
"Nothing is as subjective as reality"
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http://www.xs4all.nl/~reinoud
__________________________________________________

On Nov 24, 2005, at 21:00 , Christopher Kings-Lynne wrote:

How come these give slightly different results?

test=# SELECT POW(2,-2);
pow
------
0.25
(1 row)

test=# SELECT POWER(2,-2);
power
-------
0.25
(1 row)

(Note width of result field.)

It appears that the line is extended one underscore beyond the width
of the wider of the attribute name and value. Am I missing something?

test=# create table foo (this_is_a_long_attribute text not null,
short_attr text not null);
CREATE TABLE
test=# insert into foo (this_is_a_long_attribute, short_attr) values
('narrow_value', 'this_is_a_very_wide_value');
INSERT 0 1
test=# select * from foo;
this_is_a_long_attribute | short_attr
--------------------------+---------------------------
narrow_value | this_is_a_very_wide_value
(1 row)

Michael Glaesemann
grzm myrealbox com

On Thu, 24 Nov 2005 20:00:21 +0800
Christopher Kings-Lynne <chriskl@familyhealth.com.au> wrote:

How come these give slightly different results?

test=# SELECT POW(2,-2);
pow
------
0.25
(1 row)

test=# SELECT POWER(2,-2);
power
-------
0.25
(1 row)

(Note width of result field.)

The width of the label? Note that the first is controlled by the
result. The width of the result is four. Add a padding space on each
end and you get six. With the second the label (power vs. pow) is
larger than the result so it controls the width. It is five so add a
padding space on each end and you get seven, one more than the first.
Check these out.

test=# SELECT POW(2,-2) AS REALLY_BIG_LABEL;
really_big_label
------------------
0.25
(1 row)

test=# SELECT POWER(2,-2) AS X;
x
------
0.25
(1 row)

-- 
D'Arcy J.M. Cain <darcy@druid.net>         |  Democracy is three wolves
http://www.druid.net/darcy/                |  and a sheep voting on
+1 416 425 1212     (DoD#0082)    (eNTP)   |  what's for dinner.

Also, POW() is not documented here:

http://www.postgresql.org/docs/8.1/interactive/functions-math.html

Chris

Christopher Kings-Lynne wrote:

It appears that the line is extended one underscore beyond the width of
the wider of the attribute name and value. Am I missing something?

Ah yes, I'm stupid :P

Chris

Christopher Kings-Lynne wrote:

Also, POW() is not documented here:

I think POW is just there for backward compatibility and people should
use POWER().

---------------------------------------------------------------------------

http://www.postgresql.org/docs/8.1/interactive/functions-math.html

Chris

Christopher Kings-Lynne wrote:

How come these give slightly different results?

test=# SELECT POW(2,-2);
pow
------
0.25
(1 row)

test=# SELECT POWER(2,-2);
power
-------
0.25
(1 row)

(Note width of result field.)

Chris

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