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What is a loopback linked server?
Basically Loopback linked servers are mainly useful when testing an application that uses distributed queries on a single server network. Note that they cannot be used in a distributed transactions.
Why linked Servers are bad?
Problem (the bad) When SQL Server runs query with Linked Server, it will use the least optimal execution plan due to lack of knowledge of those remote tables. Meaning, your local SQL Server is clueless on remote table indexes and statistics, so it might use incorrect joining mechanism and might be grossly inefficient.
When to use a loop back linked server?
Basically Loopback linked servers are mainly useful when testing an application that uses distributed queries on a single server network. Note that they cannot be used in a distributed transactions. In terms of performance, there will be performance impact when you do selects or joins using LOOPBACK server as all the data has to go across wire.
What can a linked server do for SQL Server?
Linked servers enable the SQL Server Database Engine and Azure SQL Database Managed Instance to read data from the remote data sources and execute commands against the remote database servers (for example, OLE DB data sources) outside of the instance of SQL Server.
What should the name of a linked server be?
This four-part name should be in the form linked_server_name.catalog.schema.object_name. Linked servers can be defined to point back (loop back) to the server on which they are defined. Loopback servers are most useful when testing an application that uses distributed queries on a single server network.
How does a linked server query optimizer affect performance?
In terms of performance, there will be performance impact when you do selects or joins using LOOPBACK server as all the data has to go across wire. For Linked Server – Query optimizer creates an execution plan by looking at the query nomenclature and breaks it into remote and local queries.