On Fri, May 31, 2002 at 01:49:11AM -0300, Cesar Mello - Axi wrote:
> Hello,
>
> I intend to use MySQL in a data acquisition software. The actual
> version stores the acquired data straight in files. The sample rate
> can get up to 50 kHz. I would like to know if there is some way to
> improve MySQL insert rate. The following C++ code with mysql++
> takes 5 seconds to execute in my Athlon 1.33 machine:
Is the process disk bound or cpu bound? Put another way, does the cpu
max out during this process?
> sql_create_2 (teste1, 1, 2, double, datahora, double, valor1)
>
> int main() {
> try { // its in one big try block
>
> Connection con(use_exceptions);
> con.connect("cesar");
> Query query = con.query();
>
> teste1 row;
> // create an empty stock object
>
> for (int i=1;i<50000;i++)
> {
> row.datahora = (double) i;
> row.valor1 = i / 1000;
>
> query.insert(row);
> query.execute();
> }
>
> As you can see there are only two fields: a double timestamp and a
> double value. In the real application there are some more double
> values. I need to decrease this time to less than 1 second. Is there
> any kind of buffered inserts or maybe a way that I could pass a
> matrix?
You can boost the performance by inserting several records at the same
time in one querey using MySQL's extended insert syntax:
INSERT INTO my_table VALUES (foo, foo), (bar, bar), (z, z)...
Try batching them in groups of 100 or even 1000 to see how it
performs.
> I'm shocked with the performance of MySQL, a similar query to
> compute 1 million records takes 1.17 seconds in MySQL and around 6
> seconds in the current system. So if I can decrease the insert time
> I'll definetly use MySQL!
Welcome to MySQL. :-)
There's an alternative that I have in mind, but it'd be good to see
how much closer those get you before getting into it.
Jeremy
--
Jeremy D. Zawodny, <[EMAIL PROTECTED]>
Technical Yahoo - Yahoo Finance
Desk: (408) 349-7878 Fax: (408) 349-5454 Cell: (408) 685-5936
MySQL 3.23.51: up 1 days, processed 28,531,290 queries (274/sec. avg)
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