Question

I have a requirement where i have create replication between two tables with different names and which have different column names. Is it possible to create such replication.

server A                                            server B
----------                                          ----------
Table : Test                                        Table : SUBS
--------------                                      ---------------
columns A,B,C                                       Columns D,E,F,G,H

I want to configure replication so that column A data is replicated to column D, column B data is replicated to column E, column C data is replicated to column F

Answer 1

Apparently, the answer is: “When you define the article, you’ll have to set the @vertical_partition parameter to true and then add the columns that you want with sp_articlecolumn.”

However, I have to ask why you’re doing this. Replication in my mind isn’t a general tool for moving data around between unlike databases but for keeping two identical databases in sync.

Other brainstorm ideas:

• You could create a new source table that does match the destination table, and use a trigger to keep the source table synchronized.
• Push the source table intact to the destination and do the MERGE in the destination database.
• Replication may not really be the right solution, here. What are the business rules & requirements that are calling for this to be done? Have you considered using SSIS?
• If there IS a need for the two tables to be in exact synchronization all the time, then what is the channel of changes to the source table–an application? It almost sounds like your application needs a new level of abstraction, a data write layer that knows how to write to two sources at the same time.

Trying to keep data synchronized between two different databases can be a problem. There can be all sorts of subtle problems with race conditions, lack of distributed transactions (affecting consistency and response to failures), problems with the workarounds created to deal with not having distributed transactions, and so on and so forth. Can you instead create a linked server and some views that actually make the data in one database real-time accessed from the other?

Please tell us more about your requirements and why you need to do this.

Update

If you’re going the manual update route note that you can’t apply a time period’s insert, update, and delete operations en masse. You have to apply them one at a time, in order. If you are instead working with current state rather than intermediate data operations, then you can do all rows at once. I will show you the MERGE example, not the history-playback one.

BEGIN TRAN;

DELETE D
FROM LinkedServer.dbo.Dest D WITH (TABLOCKX, HOLDLOCK)
WHERE
   NOT EXISTS (
      SELECT *
      FROM Source S
      WHERE D.Key = S.Key
   );

UPDATE D
SET
   D.Col1 = S.Col4,
   D.Col2 = S.Col5,
   D.Col3 = S.Col6,
   D.Col4 = S.Col7,
FROM
   LinkedServer.dbo.Dest D
   INNER JOIN Source S ON D.Key = S.Key
WHERE
   D.Col1 <> S.Col4
   OR EXISTS (
      SELECT D.Col2, D.Col4
      EXCEPT
      SELECT S.Col3, S.Col6
   ); -- or some other way to handle comparison of nullable columns

INSERT LinkedServer.dbo.Dest (Col1, Col2, Col3)
SELECT Col4, Col5, Col6
FROM Source S WITH (TABLOCK, HOLDLOCK)
WHERE
   NOT EXISTS (
      SELECT *
      FROM LinkedServer.dbo.Dest D
      WHERE S.Key = D.Key
   );

COMMIT TRAN;

You may find it better to push the whole table and do the merge operation on the destination server.

The lock hints I put in on the first query are important if you’re going to have a consistent point-in-time snapshot. If you don’t care about that, then take the locking hints out.

If you find that updates across the linked server are slow, then push the entire table in one piece to a temporary staging table on the remote server, and do the MERGE in a script entirely on the remote server.