Creating objects in the database

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I am doing some timings with the Prevayler database. I inserted 20000 items into the database and timed this operation. The experiment was repeated 10 times. The resulting times differ widely and have a high standard deviation. Does anybody have an explanation as to why the same experiment should have such widely different timings?

 

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Hi William,

 

Thanks for the reply to my query. About the IO, I have ensured that there is no other unnecessary process running on the machine during the operation. And also, about the second problem, I increased the Java heap size to 512MB which should be more than adequate for this operation. Any other ideas that I may try?

 

The objects are created in a single transaction.

-----Original Message-----
From: Klaus Wuestefeld [klauswuestefeld@...] 
Sent: Friday, February 06, 2009 11:04 PM
To: Open discussion about the Prevayler project.
Subject: Re: [Prevayler-discussion] Creating objects in the database

Also: Are you creating 20000 objects in a single transaction or in
20000 separate transactions?


On Fri, Feb 6, 2009 at 6:49 PM, Klaus Wuestefeld
klauswuestefeld@... wrote:
  

Are you doing SCADA or OLTP?


On Fri, Feb 6, 2009 at 3:24 PM, William Pietri william@...
    

wrote:
  

Khayundi, Peter wrote:

I am doing some timings with the Prevayler database. I inserted 20000
      

items
  

into the database and timed this operation. The experiment was
      

repeated 10
  

times. The resulting times differ widely and have a high standard
      

deviation.
  

Does anybody have an explanation as to why the same experiment should
      

have
  

such widely different timings?



Hi, Peter. My first two guesses: other IO on the same disk and Java
      

garbage
  

collection. You can reduce problems with the first by using a
      

separate disk,
  

and with the latter by giving Java lots more RAM than necessary.
      

There are
  

also assorted tunings you can do, but those depend on OS and JDK
      

version.
  

William

--
William Pietri - william@... - +1-415-643-1024
Agile consulting, coaching, and development: http://www.scissor.com/
We'd love feedback on our new blog: http://agilefocus.com/






      

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I was not aware that the database was creating 20000 separate transactions. If anyone has an idea of how I can modify my code to ensure that I do not create 20000 seperate transactions, please assist me on that.

 

From: William Pietri [william@...]
Sent: Monday, February 09, 2009 7:42 PM
To: Open discussion about the Prevayler project.
Subject: Re: [Prevayler-discussion] Creating objects in the database

 

Just to be clear, each object is saved in its own transaction, so that's 20000 separate transactions.

William

Khayundi, Peter wrote:

The objects are created in a single transaction.

-----Original Message-----

From: Klaus Wuestefeld [klauswuestefeld@...] 

Sent: Friday, February 06, 2009 11:04 PM

To: Open discussion about the Prevayler project.

Subject: Re: [Prevayler-discussion] Creating objects in the database

Also: Are you creating 20000 objects in a single transaction or in

20000 separate transactions?

On Fri, Feb 6, 2009 at 6:49 PM, Klaus Wuestefeld

klauswuestefeld@... wrote:

Are you doing SCADA or OLTP?

On Fri, Feb 6, 2009 at 3:24 PM, William Pietri william@...

wrote:

Khayundi, Peter wrote:

I am doing some timings with the Prevayler database. I inserted 20000

items

into the database and timed this operation. The experiment was

repeated 10

times. The resulting times differ widely and have a high standard

deviation.

Does anybody have an explanation as to why the same experiment should

have

such widely different timings?

Hi, Peter. My first two guesses: other IO on the same disk and Java

garbage

collection. You can reduce problems with the first by using a

separate disk,

and with the latter by giving Java lots more RAM than necessary.

There are

also assorted tunings you can do, but those depend on OS and JDK

version.

William

--

William Pietri - william@... - +1-415-643-1024

Agile consulting, coaching, and development: http://www.scissor.com/

We'd love feedback on our new blog: http://agilefocus.com/

------------------------------------------------------------------------

------

Create and Deploy Rich Internet Apps outside the browser with

Adobe(R)AIR(TM)

software. With Adobe AIR, Ajax developers can use existing skills and

code

to

build responsive, highly engaging applications that combine the power

of

local

resources and data with the reach of the web. Download the Adobe AIR

SDK and

Ajax docs to start building applications

today-http://p.sf.net/sfu/adobe-com

_______________________________________________

To unsubscribe go to the end of this page:

http://lists.sourceforge.net/lists/listinfo/prevayler-discussion

_______________________________________________

"Databases in Memoriam" -- http://www.prevayler.org

------------------------------------------------------------------------

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Create and Deploy Rich Internet Apps outside the browser with

Adobe(R)AIR(TM)

software. With Adobe AIR, Ajax developers can use existing skills and

code to

build responsive, highly engaging applications that combine the power of

local

resources and data with the reach of the web. Download the Adobe AIR SDK

and

Ajax docs to start building applications

today-http://p.sf.net/sfu/adobe-com

_______________________________________________

To unsubscribe go to the end of this page:

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_______________________________________________

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software. With Adobe AIR, Ajax developers can use existing skills and code to

build responsive, highly engaging applications that combine the power of local

resources and data with the reach of the web. Download the Adobe AIR SDK and

Ajax docs to start building applications today-http://p.sf.net/sfu/adobe-com

_______________________________________________

To unsubscribe go to the end of this page: http://lists.sourceforge.net/lists/listinfo/prevayler-discussion

_______________________________________________

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Ajax docs to start building applications today-http://p.sf.net/sfu/adobe-com

_______________________________________________
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