SQL Server, most of the time, does not execute the exact query; It modifies the query internally to achieve results at a lower cost.
Tables are not read in the same order that are mentioned in the query; There are very weird reasons that SQL Server reads from tables in an absolutely different order than specified in the query.
Execution Plan reveals the ultimate modified version of query SQL Server executes.
Reading Execution Plans is very tricky. It looks to be simple, however it's not.
You can get a whole idea by the icons in an Execution Plan, however, there are many important details that are hidden between the lines. You need to know the alphabets to be able to read, understand and analyze the Execution Plan.
In order to read Execution Plans, you need to know the related concepts and requirements that are not easily found in one place. We have created the one place for you to go and learn it all from A to Z.
There are multiple algorithms to perform one single operation in SQL Server. Many ways to read from a table, or to perform an INNER JOIN, .....
Each of the algorithms has its own pros and cons; and SQL Server makes the good enough choice based on multiple criteria.
We help you understand the different algorithms, and the criteria by which SQL Server chooses one. And ultimately, you can make some changes to help SQL Server change the choice to an even better algorithm.
The way SQL Server interprets queries is way different from human interpretation. From human perspectives, a table is just where data resides. However, from SQL Server's perspective, there are many other things associated with that table; Indexes, Statisics, fragmantation, ....
The different perspectives result in two absolutely different interpretations of a query. Understanding Execution Plans helps understand SQL Server's perspective and interpretation; and helps you tweak SQL Server to find a more efficient way of executing the query.
This mobile app provides a fast and easy way of learning Execution Plans.
You will learn the Execution Plan alongside all the knowledge requirements in one single app.
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The app is currently offered on Android.