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SQL Server Agent jobs are key components of replication. A number of SQL Agent jobs are created by replication. 1) Snapshot Agent: The Snapshot Agent is a SQL Agent job that takes and applies the snapshot either for setting up transactional or merge replication or for a snapshot replication. 2) Log Reader Agent: The Log Reader Agent is the SQL Agent job that reads the transaction log on the publisher and records the transactions for each article being published into the distribution database. 3) Distribution Agent: The Distribution agent is the SQL Agent job that reads the transactions written to the distribution database and applies them to the subscribing database. 4) Merge Agent: The Merge agent is the SQL Agent job that manages activities of Merge replication. 5) Other Agents: You may come across quite a few other SQL Agent Jobs, as described in the following list a) Queue Reader Agent b) History Agent c) Distribution Cleanup d) Expired subscription cleanup e) Repl

Let us look at the STATISTICS IO output for the example of the query. This is a session level setting STATISTICS IO provides you with I/O related information for the statement you run. DBCC DROPCLEANBUFFERS GO SET STATISTICS IO ON--This is session level command GO SELECT SalesOrderID,OrderDate,CustomerID FROM dbo.New_SalesOrderHeader GO SET STATISTICS IO OFF If we run the above command in AdventureWorks2008 database we will get the results as below Table ‘New_SalesOrderHeader’. Scan count 1, logical reads 799, physical reads 0, read-ahead reads 798, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0. Scan Count: Scan count tells you that how many times the table was accessed for this query. Logical Reads: This counter indicates that how many pages were read from data cached. In this case total 799 pages read from data cache. PhysicalReads: This counter indicates that the number pages read from the disk here it is 0 that means there is no physical read from the

ipconfig /release ipconfig /flushdns ipconfig /renew