Relational databases have locking and concurrency built in.
If one user has an uncommitted change to a row, other attempts to update the
row will block until the first user commits or rolls back.
Unlike EJB servers, databases have separate read and write locks, deadlock
detection and resolution. There are tools in most relational databases to
kill particular processes, to determine how many locks a process holds, how
much IO and CPU a process is using, to automatically kill processes which
use more than some limit of locks, CPU, IO etc for the user or session.
Some databases (Yes - Oracle, PostgreSQL, Solid, Interbase. Not - DB2,
MSSQL, Sybase) have versioning. This enables read only users of the
database to view the old committed changes to the database while other
uncommitted changes are made. This makes it possible for reads of a
database to never block.
EJB's are typically non reentrant. This reduces concurrency.
Brendan
-----Original Message-----
From: Aby Mathew [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, November 17, 1999 5:43 PM
To: 'Brendan Johnston'
Cc:
[EMAIL PROTECTED]
Subject: RE: [ND] TP's and NetD
Brendan,
Could you elaborate a little on this:
> Oracle will serialize 200 requests to update one row.
Thanks,
Aby
> -----Original Message-----
> From: Brendan Johnston
[mailto:[EMAIL PROTECTED]]
> Sent: Wednesday, November 17, 1999 2:44 PM
> To: Gregory Bohmer
> Cc:
[EMAIL PROTECTED]
> Subject: Re: [ND] TP's and NetD
>
>
> Gregory,
>
> Standard WebLogic does not come with Tuxedo.
> Oracle will serialize 200 requests to update one row.
>
> Brendan
>
>
> -----Original Message-----
> From: Curt Springer
> [mailto:[EMAIL PROTECTED]]
> Sent: Wednesday, November 17, 1999 11:56
AM
> To: Gregory Bohmer
> Cc:
> [EMAIL PROTECTED]
> Subject: Re: [ND] TP's and NetD
>
> Standard ND (not using PACs, EJBs, just
using RDBMS/JDBC
> service) has no
> concept of data integrity, AFAIK. It only
manages
> resources, i.e., how
> many requests are outstanding, and how many
db
> connections
> are available at
> the moment. What those requests are doing
is somebody
> else's department.
>
> - Curt Springer, Team ND
>
>
> At 02:39 PM 11/17/99 -0500, Gregory Bohmer
wrote:
> >Here's a general question for everybody. I
recognize
> >that BEA WebLogic uses their own TP Monitor
called
> >Tuxedo to help queue update/delete
requests, and ensure
> >data integrity. What does NetD use? For
instance,
> >if 200 threads on the server (from client
> calls) are all
> trying
> >to simulataneously update the same row in
the
> underlying
> >Oracle database, what kind of queuing and
the like are
> >occuring in the NetD app server?
> >
> >How does this translate to the PeopleSoft
PAC?
> >
> >Thanks as always.
> >
> >Regards,
> >Gregory, HHMI
> >
>
>
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