Oleg Lebedev wrote:
Andy,
I ran the query 3 times in a sequence and performance did improve, which is good news. I am actually executing this query in 5 concurrent threads. Each thread performance conforms to the same pattern: first query run takes about 2000 ms, the second run ~ 60ms and the third run is ~ 15ms. I hope that this overhead is per JVM and not per query!
Are there any optimizations that I can do to improve PB performance? As far as I understand PB provides the best performance compared to ODMG and JDO, is that right?
Yes, ODMG and JDO implementation use the PB-api to do their work. Please have a look in http://db.apache.org/ojb/performance.html
regards, Armin
Thanks.
Oleg
-----Original Message-----
From: Andy Malakov [mailto:[EMAIL PROTECTED] Sent: Friday, February 13, 2004 4:17 PM
To: OJB Users List
Subject: Re: Slow query via PersistenceBroker
Hello Oleg,
OJB needs some time perform one-time initialization (load all library
classes, initialize metadata registry, etc). Execute your test method several times to warm up OJB and JVM before
measuring it performance.
----- Original Message ----- From: "Oleg Lebedev" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Friday, February 13, 2004 6:04 PM
Subject: Slow query via PersistenceBroker
Hi all.
I just barely started using OJB and have a problem with performance. I
was following "The Persistence Broker API" tutorial and tried to
retrieve a single record from the database table which contains about
150 rows. It takes 1500ms to execute this query and get the result back!
I am using SQL Server and the query takes a couple of milliseconds when
executed directly from the database.
In the code below it takes 800ms to allocate the broker and 600ms to
execute the query. Why is it so slow and what's the best way to avoid
such delays?
Thanks.
Oleg
CODE:
public static Objective findObjectiveById(int id) {
System.out.println("findObjectiveById(" + id + ")"); long start = System.currentTimeMillis(); Objective result = null; PersistenceBroker broker = null;
try { broker = PersistenceBrokerFactory.defaultPersistenceBroker();
System.out.println("Allocated broker in " + (System.currentTimeMillis()
- start) + "ms.");
start = System.currentTimeMillis();
// For small datasets use Collection as shown below. Criteria crit = new Criteria(); crit.addEqualTo("objid", new Integer(id)); QueryByCriteria query = QueryFactory.newQuery(Objective.class, crit);
System.out.println("Created query in " + (System.currentTimeMillis() - start) + "ms."); start = System.currentTimeMillis();
try { // ask the broker to retrieve a Collection Collection results = broker.getCollectionByQuery(query);
System.out.println("Executed query in " + (System.currentTimeMillis() - start) + "ms."); start = System.currentTimeMillis();
// print the results Iterator iter = results.iterator(); if (iter.hasNext()) { result = (Objective)iter.next(); }
System.out.println("Obtained result in " + (System.currentTimeMillis() - start) + "ms."); start = System.currentTimeMillis();
} catch (Throwable t) { t.printStackTrace(); }
} catch (Throwable t) { t.printStackTrace();
} finally {
if (broker != null) broker.close(); System.out.println("DONE executing findObjectiveById.");
}
return result;
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