Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Usenet -> comp.databases.theory -> Re: Replication

Re: Replication

From: Hugh O'Neill <hugh.oneill_at_btconnect.com>
Date: Tue, 28 May 2002 00:33:58 +0100
Message-ID: <3CF2C265.6576374@btconnect.com>


Comments in line below:

Graham Bellamy wrote:

> >
> >
> > Graham Bellamy wrote:
> >
> > > > "Hugh O'Neill" <hugh.oneill_at_btconnect.com> wrote in message
> > > > news:3CC52268.D6D6B8E1_at_btconnect.com...
> > > > > Replication is for situations where users are not on the same network.
> > > > Inherently, updating
> > > > > with the central master will be infrequent. I don't think this is for
> > > > you!
> > >
> > > What if a sales rep wants to be able to use the db on his laptop at home, or on the
> road
> > > during business hours. If I put a replica on his laptop, he could bring it back in the
> > > morning and update. But when he makes a quote, my code chooses the next quote number
> (PK)
> > > for him, which being disconnected from the network, will at some time produce
> duplicates
> > > with the back end on the server. Firstly, how will this get updated to sort out the
> > > duplication? Secondly, if he then uses this number for some reason, maybe in a word
> > > document, then the number gets changed upon updating, this will screw his paperwork
> (or
> > > non-linked information) up. How do I cope with this?
> > >
> > > TIA
> > > Graham
> >
> > "Hugh O'Neill" <hugh.oneill_at_btconnect.com> wrote in message
> news:3CF1753D.3176F222_at_btconnect.com...
> > The following ideas may be be useful and you should look at "AutoNumber fields and
> replication"
> > in Help so so can see what happens to Autonumber ( I'd recommend setting its 'Field
> Size' to
> > 'Replication ID' for this application.
> >
> > Autonumber will give the system a unique identifier for your 'quote' records but don't
> be
> > tempted to use it for the actual 'quote' number! Instead, use one of several numbering
> systems
> > used for document numbers. On the Salesman's machines the numeric value produced will
> be unique
> > on his machine.
> >
> > When his records are synchronised to the Office system, his 'quote' numbers may be the
> same as
> > other people's so you must make sure that field allows duplicates. All 'quote' records
> should
> > have another field containing an automatic identifier to show the Salesman or Terminal
> and that
> > identifier, with the above number, forms the 'quote' reference that appears on documents
> and
> > other reports. Again, don't be tempted to put the number and Salesman identifier into
> one
> > string in one field. If you do, you will almost certainly be sorry later!
> >
> > Remember, the records have unique identifiers given them by the Replication ID
> Autonumber and
> > the 'quote' number is just a piece of data in the record like a post code. Access will
> use the
> > Autonumber for handling internal links and you will use the 'quote' ref for the human
> side of
> > things.
> >
> > hth
> >
> > Hugh
> >
> Thanks Hugh, I'll give it some consideration. My first thoughts are that I don't like the
> duplication of the number part of the Quote number; I was hoping to keep them unique from
> quote to quote. However, I am now thinking of the situation of revisions (slight
> modifications) of quotes, in which it would be visually more logical to the user to
> duplicate the number part, and add a revision field. So if I'm going to do that, I guess
> adding the salesman's initials to the number is not much different.
>

Since the systems are seldom connected, there's no real way of avoiding duplication at the numeric level. You could consider issuing blocks of numbers for each relevant user but that's going to be very messy, hard to maintain and actually achieve nothing that a simple salesman identifier doesn't do anyway.

>

> Is it a standard practice to copy an entire record (with all it's child relations), even
> if the revision is to adjust one field (could be any field)? I can't think of any other
> practical way of doing it. Surely this blows Normalization to pieces.

I don't understand what you mean here. What copying are you referring to? If you mean the replication, what that does is to synchronize the temporarily connected systems so their data is made the same. When the systems are separated again, each remains normalised as an individual database system.

hth

Hugh

>
>

> Graham
Received on Mon May 27 2002 - 18:33:58 CDT

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US