load balancing in the application layer

1
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I am preparing for an interview. One of the topics is:

Performance tuning / Load balancing is a different concept, it consists distributing the queries sent to those servers so the load is as evenly distributed as possible. It is usually done at the application layer (or with a connection pool). The only direct relation between replication and load balancing is that you need some replication to be able to load balance, else you'd have a single server.

Can you please explain to me what does load balancing with the application layer mean as it refers to sql server ?

Can you also provide c# examples of the application layer doing the load balancing?

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c#.netsql-serversql-server-2008load-balancing
For example using a simple round robin scheduler to dispatch queries to SQL Server instances. - Adriano Repetti
I would take exception to "some replication to be able to load balance". Consider Federated and distributed tables before replicated SQL servers. If some users are read only and can have delayed data then can point them to a replicated database. - paparazzo

1 Answers

1
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Thats a pretty broad topic. I'd recomend reading some of the Microsoft literature on load balancing. Here's some documentation on load balancing in the Msft stack.