Oppz! Sorry for overlooking your timing method. In this case, I believe if you run the query in four different machines at the same time, the statistics should almost the same as running four consecutive queries in the same machine.
I believe the multi-threading implemented in the JVM and the OS is not "parallelly" the same! Best Regards, Jonathan Chiu OOCL Logistics Unit 1, 4/F., Sun Hung Kai Centre, 30 Harbour Road, Wanchai TEL: 852 . 2990 0174 FAX: 852 . 28249017 -----Original Message----- From: Haitao Jiang [mailto:[EMAIL PROTECTED] Sent: Tuesday, June 08, 2004 12:06 PM To: Mark Matthews; JONATHAN CHIU (ISD-OLAPL/HKG) Cc: [EMAIL PROTECTED]; [EMAIL PROTECTED] Subject: Re: Idea to speed up multiple jdbc connections? Yes. The time I measure like I said is purely around statement.execQuery() call. Connection creation is not a factor here at all. My database has 1.64 million rows and 4 queries are all selects, which are identical in both serial and parallel cases. In serial cases: Query 0 took 590 Query 1 took 431 Query 2 took 461 Query 3 took 440 In parallel cases: Queryer 3 query took 1552 Queryer 1 query took 1632 Queryer 2 query took 1783 Queryer 0 query took 1923 I don't understand why in 4 concurrent connection cases (already created not included in the timing) it takes more than 3 times longer to exec. a query. Thanks Haitao --- Mark Matthews <[EMAIL PROTECTED]> wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > [EMAIL PROTECTED] wrote: > > > AFAIK, creation of connection from DB is > expensive. This is one of the > > reasons why we need connection pooling. > > > > Jonathan, > > While that might be true for other databases, it's > not true for MySQL > (connections are a few ms. to create). > > The real reason to use connection pooling is as a > resource limiter so > that you do not waste MySQL server-side resources > for threads that are > effectively doing nothing. > > Haitao's issue might be due to some locking in the > database server, thus > effectively serializing his four connections, or he > might not be > actually producing enough load to actually be able > to measure any > difference between his two approaches. If he could > post his DDL, the > relative size(s) of his data set(s) and the queries, > that would be > somewhere to start. > > -Mark > - -- > Mr. Mark Matthews > MySQL AB, Software Development Manager, J2EE and > Windows Platforms > Office: +1 708 332 0507 > www.mysql.com > > MySQL Guide to Lower TCO > http://www.mysql.com/it-resources/white-papers/tco.php > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.2.3 (MingW32) > Comment: Using GnuPG with Thunderbird - > http://enigmail.mozdev.org > > iD8DBQFAxRgLtvXNTca6JD8RAjiSAJ0R5b6MNW0SdY5z4eJtmfgAV0ZMtgCgtGyn > 037apgXT972UAR3Khkg7ITI= > =4bja > -----END PGP SIGNATURE----- __________________________________ Do you Yahoo!? Friends. Fun. Try the all-new Yahoo! Messenger. http://messenger.yahoo.com/ IMPORTANT NOTICE Email from OOCL is confidential and may be legally privileged. If it is not intended for you, please delete it immediately unread. The internet cannot guarantee that this communication is free of viruses, interception or interference and anyone who communicates with us by email is taken to accept the risks in so doing. Without limitation, OOCL and its affiliates accept no liability whatsoever and howsoever arising in connection with the use of this email. Under no circumstances shall this email constitute a binding agreement to carry or for provision of carriage services by OOCL, which is subject to the availability of carrier's equipment and vessels and the terms and conditions of OOCL's standard bill of lading which is also available at http://www.oocl.com. -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
