Re: Numeric performances

[PFC <lists(at)peufeu(dot)com>]

	This is a 32 bit CPU by the way.

	Consider this :

- There are 100K rows
- The CPU executes about 3 billion instructions per second if everything  
is optimum
- "SELECT sum(n) FROM test", takes, say 60 ms

	This gives about 1800 CPU ops per row.
	A Float addition versus an Int addition is a drop in the sea.

	I believe the marked difference between Floats/Ints (faster) and  
Numeric/Bigint (slower) comes from being passed by value or by pointers.

	A single access which misses the CPU cache and has to go fetch data from  
the real RAM spends a lot more cycles than the simple loops in a NUMERIC  
addition which will hit L1 cache.
	Nowadays cache access patterns matter more than how many actual CPU  
instructions are executed...

> > forum_bench=> SELECT sum(i) FROM test;
> > Temps : 46,589 ms
> > forum_bench=> SELECT sum(f) FROM test;
> > Temps : 63,865 ms

> > forum_bench=> SELECT sum(b) FROM test;
> > Temps : 157,018 ms
> > forum_bench=> SELECT sum(n) FROM test;
> > Temps : 124,816 ms