This might help:
http://jena.apache.org/documentation/sdb/javaapi.html#connection-management
Andy
On 15/04/13 14:38, David Jordan wrote:
So every call to a method of Model or OntModel is done in a separate
transaction? This could easily explain the poor performance I am getting, and
those of others who have complained about SDB performance in this group.
Your code example is very sparse. Are there calls to make to get to an
associated JDBC transaction? All of the JDBC connection info is described in
Jena's assembler files, so it seems like an API should be available to access
the needed JDBC objects.
-----Original Message-----
From: Damian Steer [mailto:cm...@bristol.ac.uk] On Behalf Of Damian Steer
Sent: Monday, April 15, 2013 9:27 AM
To: users@jena.apache.org
Subject: Re: Concurrency in Jena/SDB
On 15 Apr 2013, at 12:35, "Lebling, David (US SSA)"
<david.lebl...@baesystems.com> wrote:
Andy,
I was hoping you might have some guidance as to what you mean by "You need to
control the JDBC transaction in your code to get isolation between JVMs."
Is there some interface in SDB that will accomplish this, or does this require
SQL-implementation-specific code, thus tearing down the SDB façade? If it does
require such implementation-specific code, do you have any pointers to examples
which do it correctly? Is it necessary to write one's own transaction
begin/commit/abort methods?
SDB (as you'd expect) handles transactions itself by default. All model
operations happen in a single transaction, with a minor wrinkle around really
big loads (it will start committing every 20,000 triples iirc to avoid huge
transactions).
You can also wrap operations like this to get some of that behaviour across a
number of operations:
model.notifyEvent(GraphEvents.startRead) ; try { ... do add/remove operations
...
} finally {
model.notifyEvent(GraphEvents.finishRead) ; }
However it's not especially smart, so you can take control of the transaction
yourself by setting autocommit to false on the JDBC connection. SDB will then
assume the client is responsible for managing the transactions.
Just remember to commit() and reset autocommit when you finish.
Damian
