Thread: Performance of loop

Hi,
  First of all, I would like to thank the postgresql team for providing this wonderful product.

  Coming to the point, in postgresql jdbc driver coding, I saw many inefficient "for" loops. For eg in V2Query.class file
 While parsing the parameterized query, there is a "for" loop as this
 
for (int i = 0; i < query.length(); ++i)
{
char c = query.charAt(i);

....
.....
}

In the above coding, say if the length of the query is 1000 characters then the query.length() is evaluated 1000 times there by reducing the performance.
 I think the loop can be rewritten as

for (int i = 0,c=query.length(); i < c; ++i)
{
char c = query.charAt(i);

....
.....
}

with regards,
S.Gnanavel
Software Engineer
Satyam Computer Services Ltd

Gnanavel S wrote:

> In the above coding, say if the length of the query is 1000 characters
> then the query.length() is evaluated 1000 times there by reducing the
> performance.
>  I think the loop can be rewritten as
>
> for (int i = 0,c=query.length(); i < c; ++i)
> {
> char c = query.charAt(i);
>
> ....
> .....
> }

Have you benchmarked this? I doubt it's really a hotspot given that the
JIT is likely to inline length(). Premature optimization and all that..

-O

No. I havn't done any benchmark, but lot of such inefficient loops may hit the performance.




--
with regards,
S.Gnanavel
Satyam Computer Services Ltd.