A feature often overlooked while tuning queries is Client Statistics located right on SSMS editor bar.

Other ways of opening Client Statistics include:

SHIFT + ALT + S and Menu Bar – Query -> Include Client Statistics

Client Statistics is useful when the user needs to gather information about execution times, processing times, the amount of data sent between client and server, etc. it’s very easy to use. Simply turn it on using one of the methods above and execute your query.

In this example I’m using the following query:

SELECT pc.FirstName
,pc.LastName
,pc.EmailAddress
,he.Title
,hh.Rate
FROM Person.Contact pc
JOIN HumanResources.Employee he ON pc.ContactID = he.ContactID
JOIN HumanResources.EmployeePayHistory hh ON he.EmployeeID = hh.EmployeeID
WHERE hh.Rate > 10
ORDER BY hh.Rate

After executing the query you will notice a new tab labeled Client Statistics:

After looking at the statistics provided for Trial 1 you can see the processing time = 39ms, execution time = 46ms, etc.

After the running the same query again I get the following results under Trial 2:

This time processing time went up to 45ms and execution time went up to 51ms. It also has an average column to compare overall results. The green and red arrows represent differences between trials. Green arrows indicate improved statistics and red arrows indicate degrading statistics.

A max of 10 trials can be run with the 11^th trial dropping the 1^st trial and so on. To reset statistics, on the menu bar, go to Query, Reset Client Statistics.

This is great when tuning indexes because you can see different statistics as you add/delete indexes.

Statistics IO and Statistics TIME can help in performance tuning from a granular level and saves time compared to Execution Plans, SQL Server Profiler, etc. Let’s looks at an example of these two commands:

There a few different ways in which you can turn on these commands inside SQL Server Management Studio. If you want every query window to open up with statistics you can go to Tools, Options, Query Execution, SQL Server, Advanced and check SET STATISTICS TIME and SET STATISTICS IO:

Most of the time you will just want to use statistics for a certain troublesome query. To turn these commands on for a specified query window, open the query window and go to Query, Query Options, Execution, Advanced and check SET STATISTICS TIME and SET STATISTICS IO:

Or you can simply use T-SQL and type the following to turn statistics on

SET STATISTICS IO ON
SET STATISTICS TIME ON

And to turn off simply use:

SET STATISTICS IO OFF
SET STATISTICS TIME OFF

In this example I’m going to run a query from AdventureWorks using statistics:

SET STATISTICS IO ON
SET STATISTICS TIME ON

SELECT pc.FirstName
,pc.LastName
,pc.EmailAddress
,he.Title
,hh.Rate
FROM Person.Contact pc
JOIN HumanResources.Employee he ON pc.ContactID = he.ContactID
JOIN HumanResources.EmployeePayHistory hh ON he.EmployeeID = hh.EmployeeID
WHERE hh.Rate > 10
ORDER BY hh.Rate

After the query finishes it will show you results like normal but if you click on the Messages tab you will see some extra information:

You will see IO information at the top:

Scan Count – Number of index or table scans
Logical Reads – Number of pages read from the data cache
Physical Reads – Number of pages read from disk
Read-Ahead Reads – Number of pages placed into the cache for the query
LOB Logical Reads – Number of text, ntext, image, or large value pages read from the data cache
LOB Physical Reads – Number of text, ntext, image, or large value type pages read from disk
LOB Read-Ahead Reads – Number of text, ntext, image, or large value type pages placed into the cache for the query

Execution TIME information will be directly below:

CPU Time: How long the query worked with the CPU
Elapsed Time: How long the query took to gather data

Statistics, in general, is an excellent starting point to see why you might have a poor performing query. You can gather results such as execution time, compile time, reads, writes, cost, etc.