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Performance Tuning Archives - SQL Server Blogs, Events, Webcasts, Videos, SQL Server learning & education Performance Tuning Archives - SQL Server Blogs, Events, Webcasts, Videos, SQL Server learning & education

Performance Tuning

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SQL Server – Join Operation

In this blog we’ll find how SQL Server works when we do join operation. SQL Server optimizer chooses one of the below physical operator to perform logical join operation.

Hash Match
Merge Join
Nested Loop Join

As far as performance is concern let me tell you, we can’t say which one will best.Each operator has its own advantages […]

SQL Server 2016 – Batch Mode Processing with Serial Plan

Hello Friends,

There are lots of features and improvements announced by Microsoft in SQL Server 2016, one of them is providing batch mode processing with 900 rows batch size. SQL Server 2016 uses batch mode processing even if the execution plan is a serial plan which was not possible with previous versions. Due to this […]

SQL Server 2016 – Trace Flag 9453 – Disable Batch Mode Processing

Hello Friends,

In my previous blog post, we have seen the SQL Server 2016 Sort operator with batch mode processing. To compare the performance for Batch mode versus Row mode for Sort operator, I used a trace flag 9347 which disables the batch mode processing for sort operator. Now the question is: Is there any […]

SQL Server 2016 – New Columns in sys.dm_exec_query_stats

Hello Friends,

There are lots of features and improvements announced by Microsoft in SQL Server 2016, one of them is adding new columns in sys.dm_exec_query_stats. These new columns capture information about threads and memory. First, I’ll show you the new added columns for collecting threads and Degree of parallelism level information.

Here total_dop represent the total […]

How to resolve High Compilations/Second problem in SQL Server

Hi Friends and Geeks!

Sharing an experience on resolution of High Compilations/Second performance counter in SQL Server from one of my consulting assignments.

The threshold for Compilations/Second is mentioned as 10% of Batch Requests/Second by various MVPs and in our case it was around 40 to 50%

Investigation Process

Investigate for queries with same query_hash but multiple plan_handles using […]

SQL Server Index Hint

SQL Server query optimizer decides which index to use, when a query is requested. SQL Server optimizer is a cost based optimizer so it picks the index which has low cost based on performance. When we design an index for a query, optimizer will utilize the defined index to generate the plan for requested […]

Clustered Index seek doesn’t guarantee optimal Query plan

I was working on removing duplicate indexes from a table. Before removing an index usually I check whether that index is used by any query or not, is there any index hint is used, looking at index usage statistics and many other factors.

If you search in web you will get many ways to identify […]

SQL Server 2016 – Database Scoped Configurations

Hi Friends,

As a DBA, we know about various Instance level settings in SQL Server like MAXDOP, Cardinality Estimator related changes and various Trace Flags etc. There may be some scenarios where you want to enable these kind of settings at the database level rather than instance level. For Example, I want to set MAXDOP […]

DMV in SQL Server 2016 CTP – sys.dm_exec_session_wait_stats

Hi Friends,

Wait stats, I hope all of us who are working with SQL Server are aware about this thing. SQL Server DBA generally uses sys.dm_os_wait_stats DMV in SQL Server to collect the data about waits. This collection is very useful for troubleshooting of various performance problems. This DMV provides the cumulative information of wait […]

The correct cardinality estimation using table variable

Hi Friends,

In my previous blog post, we have seen that SQL Sever estimates number of rows in a table variable was 1. Now the question is, Is there any way to make the correct estimation for the number of rows while using table variable?

My today’s blog post is focused on the correct cardinality estimation […]

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