Posted by Erland Sommarskog on 06/30/05 00:41

Rohit (UseLinkToEmail@dbForumz.com) writes:
> I have 2 instances of databases in 2 different cities.Data entry /
> updations are going on at both the sides.At any point of time data in
> both the databases should be same.Currently every alternate day, i am
> performing update / insert / deletes on incremental basis on both the
> sides.
> Can I implement replcation? What r the requisites I have to follow for
> replication?
>
> I do not have permenant connectyvity but I need to connect using ISDN
> line to a remote location as and when required for doing
> synchrinisation of data.

I'm a little confused, since you say that at any point in time, the
contents of the databases should be the same. But then you talk about
not having permanent connectivity. Is that the connectivity between
the databases, or your own connectivity.

The gist of replication is that the I in ACID for transactions is
relaxed. That is, transactions should normally be Atomic, Consistent,
Immediate and D-something. With replication, you say that I does not
matter. A transaction can be replicated later at any time. This is good
if you have disconnected servers. For connected servers, replication
can still be acceptable, since the delay in most cases will not be
noticeable.

Since you need to send data in both directions, it looks as if you are
into merge replication. There are probably a bunch of requirements,
for instance the table must have GUID as keys. And then you need rules
to handle conflicts. (What if the same row is updated at both sites?)

My own knowledge only goes as far about this, so I would recommend you
to ask in microsoft.sqlserver.public.replication.
--
Erland Sommarskog, SQL Server MVP, esquel@sommarskog.se

Books Online for SQL Server SP3 at
http://www.microsoft.com/sql/techinfo/productdoc/2000/books.asp

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