What is Database Mirroring ?

Mirroring is creating an additional instance of a SQL Server, thereby increasing availability. The source instance is called Principal Server and the target instance is called the Mirrored server.

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What is the work of the DTC ?

The DTC manages the committing of transactions when there are several different data sources involved.

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What is the expansion of DTC ?

Distributed Transaction Coordinator .

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Daily Tips- Tip #73 - SQL Performance Tuning

"SET NOCOUNT ON" reduces network traffic between server and client.

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Daily Tips- Tip #72 - SQL Performance Tuning

use the SQL Server's Profiler Create Trace Wizard to run the "Profile the Performance of a Stored Procedure" trace to provide you with the data you need to identify poorly performing stored procedures..

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What is a Linked Server ?

It is an alias on the local SQL Server which points to an external data source.

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Daily Tips- Tip #71 - SQL Performance Tuning

Use covering index whereever needed, it reduces logical and physical IO and increases performance.

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What are Covering Indexes?

A covering index, is a form of a composite index, includes all of the columns referenced in the SELECT, JOIN, and WHERE clauses of a query. It reduces logical and physical IO and increases performance.

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Daily Tips- Tip #70 - SQL Performance Tuning

Use Joins instead of Subqueries.

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What is the expansion of SARG ?

Search ARGument.

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What is the advantage of UNION ALL over UNION with respect to performance?

The advantage of the UNION ALL is that is does not perform the SELECT DISTINCT function where the UNION does.

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Daily Tips- Tip #69 - SQL Performance Tuning

To help identify long running queries, use the SQL Server Profiler Create Trace Wizard to run the "TSQL By Duration" trace.

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Daily Tips- Tip #68 - SQL Performance Tuning

Avoid using temp table unnecessarily, if needed explicity create them.

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Daily Tips- Tip #67 - SQL Performance Tuning

Use set nocount on at the top of each stored procedure and set nocount off at the bottom.

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Daily Tips- Tip #66 - SQL Performance Tuning

Create an index on any column that is a foreign key.

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Daily Tips- Tip #65 - SQL Performance Tuning

Create a primary key on each table you create and unless you are really knowledgeable enough to figure out a better plan, make it the clustered index.

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What is a tuple?

A tuple usually represents an object and information about that object.

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Daily Tips- Tip #64 - SQL Performance Tuning

EXISTS is efficient when most of the filter criteria is in the main query.

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Daily Tips- Tip #63 - SQL Performance Tuning

Use Indexed Columns in where clause columns as they return results faster.

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Daily Tips- Tip #62 - SQL Performance Tuning

IN is efficient when most of the filter criteria is in the sub-query.

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Daily Tips- Tip #61 - SQL Performance Tuning

Avoid using IN unnecessarily as IN is slowest..

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Daily Tips- Tip #60 - SQL Performance Tuning

Try to minimize number of subqueries in your query.

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Daily Tips- Tip #59 - SQL Performance Tuning

Use actual column names instead of '*' in the queries.

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