Re: C API -- huge result sets slowin me down
"Matt Eaton" <[EMAIL PROTECTED]> wrote:
Try to profile application from that point ...
>if (mysql_real_query(&dbase,sqlBuff,strlen(sqlBuff))) {
>printf("Pool Attributes Select Failed... dumbass\n");
>fprintf(stderr, "Error: %s\n",
>mysql_error(&dbase));
>exit(1);
>}
>
>result = mysql_store_result(&dbase);
>numRows=mysql_num_rows(result);
... to that point and then from here to ..
>for (i=0;irow = mysql_fetch_row(result);
>tempq=atoi(row[1]);
>tempP=atoi(row[0]);
>genAttrib[tempP][tempq]=atoi(row[2]);
>}
..here. I suppose the cycle could be a slowdown/
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Re: C API -- huge result sets slowin me down
Hi,
The only thing that could slow you down is that the genAttrib array will take
more and more memory as the result set grows. I would recommend you to create
a function that uses the mysql row directly instead of creating this huge
array.
something like
while ((row = mysql_num_rows(result))){
usedata(row);
}
Of course it depends on what do you need the mysql data for - but if you can
make it to use one row at a time it should run a lot more faster.
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Dobromir Velev
[EMAIL PROTECTED]
http://www.websitepulse.com/
On Tuesday 29 June 2004 08:50, Matt Eaton wrote:
> Hi all,
>
> I was hoping this was the right place for a question about the C API.
> I've been grabbing result sets from tables in the C API for a few years
> now, but I'm starting to work with result sets that are big enough to
> bog me down. Of course, the result sets aren't insanely big, so I was
> wondering why it was taking so long for me to suck them in to C,
> especially when I can run the same query from the command line using the
> binaries and they can cache it to a file on the hard disk pretty much
> instantly. So, basically, I was just hoping that I've been doing
> something wrong, or at least that there was something I could do better,
> to make my database communication as fast as the mysql command line
> tools. I've checked out their source and nothing obvious jumps out at
> me. Here's a non-functional sample of my code:
>
> int main(int argc, char *argv[] ) {
> int uid;
> int sid;
> char sqlBuff[4000];
> int err = 0;
> int i;
> // Setup the database communications space:
> MYSQL dbase;
> MYSQL_RES *result;
> MYSQL_ROW row;
>
> float **genAttrib;
>
> //... snip ...
>
>
> // Connect to the database:
> if (mysql_init(&dbase) == NULL) err = 1;
> else {
>
>
> if(mysql_real_connect(&dbase,"localhost","login","pass","test",0,NULL,CL
> IENT_FOUND_ROWS) == NULL) {
> err = 1;
> fprintf(stderr, "Failed to connect to database:
> Error: %s\n",
> mysql_error(&dbase));
> }
> }
>
> // If the connection couldn't be established:
> if(err) {
> printf("db connection failed!\n");
> exit(1);
> }
>
>
> //... snip ...
>
> // This query could have as many as a million rows returned, but
> the query itself runs quite fast. It seems to just be
> // sucking it into C that can take up to four seconds on our
> dual Xeon server.
> sprintf(sqlBuff,"SELECT A.* FROM `attribs` as A, login AS L
> WHERE A.guid=L.guid AND L.isActive=1 AND L.sid=%d AND
> A.guid!=%d",sid,uid);
> if (mysql_real_query(&dbase,sqlBuff,strlen(sqlBuff))) {
> printf("Pool Attributes Select Failed... dumbass\n");
> fprintf(stderr, "Error: %s\n",
> mysql_error(&dbase));
> exit(1);
> }
>
> result = mysql_store_result(&dbase);
> numRows=mysql_num_rows(result);
> for (i=0;i row = mysql_fetch_row(result);
> tempq=atoi(row[1]);
> tempP=atoi(row[0]);
> genAttrib[tempP][tempq]=atoi(row[2]);
> }
>
> return 0;
> }
>
> So, if someone sees something that I could change to speed things up, or
> I should direct this question elsewhere... thanks for your help and
> thanks for reading this far!
>
> Thanks again,
> Matt
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C API -- huge result sets slowin me down
Hi all,
I was hoping this was the right place for a question about the C API.
I've been grabbing result sets from tables in the C API for a few years
now, but I'm starting to work with result sets that are big enough to
bog me down. Of course, the result sets aren't insanely big, so I was
wondering why it was taking so long for me to suck them in to C,
especially when I can run the same query from the command line using the
binaries and they can cache it to a file on the hard disk pretty much
instantly. So, basically, I was just hoping that I've been doing
something wrong, or at least that there was something I could do better,
to make my database communication as fast as the mysql command line
tools. I've checked out their source and nothing obvious jumps out at
me. Here's a non-functional sample of my code:
int main(int argc, char *argv[] ) {
int uid;
int sid;
char sqlBuff[4000];
int err = 0;
int i;
// Setup the database communications space:
MYSQL dbase;
MYSQL_RES *result;
MYSQL_ROW row;
float **genAttrib;
//... snip ...
// Connect to the database:
if (mysql_init(&dbase) == NULL) err = 1;
else {
if(mysql_real_connect(&dbase,"localhost","login","pass","test",0,NULL,CL
IENT_FOUND_ROWS) == NULL) {
err = 1;
fprintf(stderr, "Failed to connect to database:
Error: %s\n",
mysql_error(&dbase));
}
}
// If the connection couldn't be established:
if(err) {
printf("db connection failed!\n");
exit(1);
}
//... snip ...
// This query could have as many as a million rows returned, but
the query itself runs quite fast. It seems to just be
// sucking it into C that can take up to four seconds on our
dual Xeon server.
sprintf(sqlBuff,"SELECT A.* FROM `attribs` as A, login AS L
WHERE A.guid=L.guid AND L.isActive=1 AND L.sid=%d AND
A.guid!=%d",sid,uid);
if (mysql_real_query(&dbase,sqlBuff,strlen(sqlBuff))) {
printf("Pool Attributes Select Failed... dumbass\n");
fprintf(stderr, "Error: %s\n",
mysql_error(&dbase));
exit(1);
}
result = mysql_store_result(&dbase);
numRows=mysql_num_rows(result);
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