4
votes
1answer
213 views

A clarification of MERGE best practices

I just wanted to ask a clarification about something on the MSDN from the "Optimizing MERGE Statement Performance" page. I am working with a data warehouse that takes in records from many different ...
3
votes
1answer
84 views

Does MERGE updates when not needed?

In SQL Server 2012, Does a merge statement like this : WHEN MATCHED THEN update SET A.len = B.len updates a row even if A.len equals to B.len ? Or does the SQL SERVER knows to ignore this ...
0
votes
4answers
833 views

How do I delete only related records in a multi-key MERGE in SQL Server?

Suppose you have something like this: Source table (variable): Values ( LeftId INT NOT NULL, RightId INT NOT NULL, CustomValue varchar(100) NULL ) Target table: Mapping ( LeftId INT NOT ...
1
vote
1answer
176 views

Merge Statement + Replication difference for SQL Server 2012

We have a SSIS package that will pull from a source database and run a merge statement to put the data into a "Master" database. (Eventually the "Master" database will be the source of truth, but we ...