Re: problem with LargeObject and commit

Well I don't see any reason not to open up the LOM class to allow you to
extend it.

Can you send a git pull?

Dave Cramer

dave.cramer(at)credativ(dot)ca
http://www.credativ.ca

On Tue, Oct 1, 2013 at 3:52 AM, Marc Cousin <cousinmarc(at)gmail(dot)com> wrote:

> Sorry, I don't think I get it, so please correct me below if I didn't.
>
> I currently use getInputStream() on my large object. How could I provide a
> connection to the extended InputStream ? I am calling a LargeObject method.
>
> Or maybe extend LargeObject to have a new getInputStream method with a
> connection provided, and then provide this connection to the extended
> InputStream ?
>
> My initial idea was to not have to provide the connection as a parameter,
> so I
> wanted to use the Lob Manager.
>
> Anyway, shouldn't streaming a large object in this special case be easier
> to
> do ? The original code (from SQL Server) didn't have to do all these
> workarounds, and I'll get this objection from people that will have to use
> this code :)
>
> Just having conn as protected instead of private in the LargeObjectManager
> would have made it possible to me to do it simply: I could have provided
> the
> connection to my extended LargeObject, and from there end the transaction
> on
> close().
>
> Regards.
>
> On Monday 30 September 2013 17:08:18 Dave Cramer wrote:
> > Marc,
> >
> > You required the connection to create the LargeObjectManager, so why not
> > just extend the InputStream and add the connection to that object.
> > When you close the input stream, close the connection ????
> >
> > Dave Cramer
> >
> > dave.cramer(at)credativ(dot)ca
> > http://www.credativ.ca
> >
> > On Mon, Sep 30, 2013 at 11:18 AM, Marc Cousin <cousinmarc(at)gmail(dot)com>
> wrote:
> > > Hi,
> > >
> > > I'm having the following problem: I need to stream a LOB to a web
> client,
> > > without consuming
> > > a lot of memory. So I am returning getInputStream() to the caller.
> > >
> > > This works perfectly, except that I have to keep a transaction open to
> > > return the large object
> > > stream, and I have (or found) no way of closing the transaction when
> the
> > > filestream is closed.
> > >
> > > So of course, if I did that, I would get a lot of IDLE in transaction
> > > sessions...
> > >
> > > So the logical way seemed to me to extend LargeObjectManager and
> > > LargeObject to have a
> > > close method on my LargeObject that closes the transaction, meaning
> that
> > > my LargeObject
> > > should have a connection attribute. So I wanted to do something like
> this
> > > (not working,
> > > it's just for the sake of explanation):
> > >
> > >
> > > public class StreamLargeObjectManager extends LargeObjectManager{
> > >
> > > public StreamLargeObject openStreamLargeObject(long oid, int
> > >
> > > mode)
> > >
> > > throws SQLException
> > >
> > > {
> > >
> > > LargeObject lo = super.open(oid, mode);
> > > StreamLargeObject so = new StreamLargeObject(lo,
> > >
> > > super.getConn()); //cannot be done because no access to connection
> > >
> > > return so;
> > >
> > > }
> > >
> > > }
> > >
> > >
> > > and
> > >
> > > public class StreamLargeObject extends
> > > org.postgresql.largeobject.LargeObject{
> > >
> > > Connection conn;
> > >
> > > LargeObject lobj;
> > >
> > >
> > > public StreamLargeObject(LargeObject lg, BaseConnection conn)
> > >
> > > throws SQLException {
> > >
> > > this.lobj = lg;
> > > this.conn = conn;
> > >
> > > }
> > >
> > >
> > > @Override
> > > public void close() throws SQLException {
> > >
> > > lobj.close();
> > > this.conn.commit();
> > >
> > > }
> > >
> > > public getInputStream() throws SQLException
> > >
> > > {
> > >
> > > return lobj.getInputStream();
> > >
> > > }
> > >
> > > }
> > >
> > >
> > > As the comment says it all, I cannot do this: conn is private in
> > > LargeObjectManager. For now, the problem has been
> > > worked around by duplicating all the LargeObjectManager code, but this
> is
> > > obviously ugly and not
> > > maintainable. So my question is: have I missed some obvious solution ?
> > > Could a getter be added to
> > > the LargeObjectManager's connection ?
> > >
> > > Regards,
> > >
> > > Marc
> > >
> > >
> > > --
> > > Sent via pgsql-jdbc mailing list (pgsql-jdbc(at)postgresql(dot)org)
> > > To make changes to your subscription:
> > > http://www.postgresql.org/mailpref/pgsql-jdbc
>
>