Using the auto-completion feature of SQL Complete add-in from dbForge Studio, we can easily specify the necessary argument: We can modify the previous statement to limit the result set to the header. To understand each section better, let’s take a closer look at the information it delivers. In the example below, we executed the DBCC SHOW_STATISTICS statement, and we received the three sections (the header, density vector, and histogram) in the output, as follows: DBCC SHOW_STATISTICS Statistics Header Or DBCC SHOW_STATISTICS (‘Object_Name’, ‘Statistic_Name’) WITH DENSITY_VECTOR Example Or DBCC SHOW_STATISTICS (‘Object_Name’, ‘Statistic_Name’) WITH STAT_HEADER If you need to retrieve a specific data set (for instance, the histogram), you can specify a required argument in the syntax: DBCC SHOW_STATISTICS (‘Object_Name’, ‘Statistic_Name’) WITH HISTOGRAM Running the above-mentioned command will output a result consisting of all three sections. You can specify a table or indexed view as an object and statistics or an index as a target. The syntax for the command is as follows: DBCC SHOW_STATISTICS (‘Object_Name’, ‘Target’) SyntaxĭBCC SHOW_STATISTICS statement returns three data sets: the header, density vector, and histogram. In fact, the query optimizer uses the statistics to opt for a better query plan, such as choosing the index seek operator instead of the index scan operator to enhance query performance by eliminating a resource-heavy index scan. Simply put, the command allows us to view the statistics that SQL Server will use to create a high-quality query plan. What is DBCC SHOW_STATISTICS CommandĭBCC SHOW_STATISTICS shows the current query optimization statistics for a table or indexed view.
#Should you be doing statistical calculations in sql how to
Therefore, in this article, we are going to look at how to collect statistical information and how to interpret it correctly. That is why it is vital to keep the statistics up to date and to understand them well.
The query optimizer embedded in your SQL Server database uses statistical data to tune execution plans according to the way your data characteristics change. They store a vast array of information about the database data that helps identify slow-running queries and allows you to devise an algorithm to optimize query execution. Database statistics are a powerful weapon.
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