Classic behaviour, which has nothing to do with postgres. Try the
program below to see the same effect. You probably should be using a
rounding function to see what you seem to expect.
cheers
andrew
#include <stdio.h>
main()
{
double x[] = { 0.1, 0.11, 0.12, 0.13, 0.14, 0.15 };
int i,n;
for (i=0 ; i < 6; i++)
{
n = x[i] * 100;
printf("%d\n",n);
}
}
Cristian Prieto wrote:
Hello, I'm using PostgreSQL 8.0.4 in Fedora Core 3, right now I'm learning a
little about the postgresql internals and the way some kind of SPs could be
written in c language; I found something really weird and I cannot explain
to me this behavior:
#include "postgres.h"
#include "fmgr.h"
PG_FUNCTION_INFO_V1(test);
Datum
repeat_item(PG_FUNCTION_ARGS)
{
int num_times;
num_times = PG_GETARG_FLOAT8(0) * 100;
PG_RETURN_INT32(num_times);
}
Inside psql this happens:
# Create or replace function test(float) returns integer as 'test.so'
language 'c' stable;
select test(0.1);
Returns 10
Select test(0.11);
Returns 11
Select test(0.12)
Returns 11
Select test(0.13)
Returns 13
Select test(0.14)
Returns 14
Select test(0.15)
Returns 14
What Is happening here?
---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
---------------------------(end of broadcast)---------------------------
TIP 4: Have you searched our list archives?
http://archives.postgresql.org
