FreeTDS Development Group

[Brian Bruns <camber AT ais.org>]

Thanks for the patch. I've commited it.

I don't really think this will affect what Mike is seeing though as a 500
byte query executes in ~10ms and a slightly larger one executes in ~150
which would be a increase in strlen calls of aproximately 20% tops.  On my
system (a pathetic 233mhz box) strlen on 500 bytes runs in about 3
microseconds, thus a 140 millisecond increase would require an astounding
47,000 calls to strlen(). And I know Mike has faster hardware than I :-) 

I think we must look to the network or the SQL Server on this one.  Any
ideas?

Brian

On 22 Oct 2000, Rusty Conover wrote:

> Brian Bruns <camber AT ais.org> writes:
> 
> > Query times are a combination of size of result set (columns and rows) and
> > the usefulness of indexes and the query optimizers ability to generate a
> > decent query plan.  You may want to run it with showplan and noexec to see
> > if your query plan is any good.  The size of the query text in the process
> > should be negligible and more importantly has nothing to do with the
> > client (ours or microsofts).  Of course there could be a bug, but I find
> > it hard to envision anything the small query/large query code differences
> > could be doing to cause it.
> > 
> > On to the meat of your post.  There should only be one reference to '512'
> > left in write.c (And I just checked in the fix for that...)  If you are
> > seeing more, then the snapshot is not picking up the right stuff.
> > 
> > Why not send me the text of the query offlist and I'll run it through
> > under TDS 4.2 with the latest code to see what's up.
> > 
> 
> 
> Brian,
> 
> The problem for large queries taking a while to send is your
> tds7_ascii2unicode() function in login.c.  In the body of your for
> loop you are continually calling strlen() which computes the length of
> the string each time the loop is executed. You really only need to
> compute the length of the string once, also you can make the length a
> constant so the function is even faster.  Here are my fixes:
> 
> char *tds7_ascii2unicode(const char *in_string, char *out_string, int 
> maxlen)
> {
>         register int out_pos = 0;
>         const size_t string_length = strlen(in_string);
>         register int i;
> 
>         memset(out_string, 0, string_length*2);
>         for (i=0; i<string_length; i++) {
>                 out_string[out_pos]=in_string[i];
>                 out_pos += 2;
>         }
>         return out_string;
> }
> 
> Cheers,
> 
> Rusty
> -- 
> Rusty Conover 
> Systems Programmer
> Zoot Enterprises Inc, www.zootweb.com
>