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Reading Query Plans with the Showplan Options

This post is about the several ways of reading the query plan (called the showplan options). Now that we know what a query plan is, why it’s helpful and what it consists of (iterators), let’s find out how we can read the query plans in SQL Server. I believe most of you are familiar with Read More

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Properties of Iterators

In this post I will continue the discussion about iterators in the context of a query execution plan. This time, I will tell you about some of their most important properties and the things to take into consideration when investigating the performance of an execution plan.

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Iterators in the Query Execution Plan

In this article I will explain the concept of iterators, in the context of the query execution plan. First, you will find out what they are. Second, I will tell you what are the main actions performed by an iterator. And last, but not least, I am going to show you how they work in Read More

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Query Execution Engine Introduction

This is the first post from my complex tutorial project called “Understanding Query Execution Plans”. This is an introductory post, in which I will  guide you through the concepts you need to know before starting to analyze the plans. 

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Learning Corner #9 – Nested transactions

In this article, I will explain what are nested transactions and how we can use them. The article is structured in the form of interview questions. Some questions may have a more detailed answer than what is needed, but the purpose is to give you a clear overview on this subject, not only a cheat Read More

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Learning Corner #7 – Introduction to Transactions

The transactions subject is a very important one in SQL Server and a must have knowledge for all the good developers. However, although mostly everybody is familiar with the concept of transactions and is also able to use them successfully in SQL Server, there may be some more sensitive issues regarding transactions which are not Read More

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Learning Corner #6 – Grouping sets in SQL Server

Grouping sets in SQL Server always comes into handy when you find yourself in the need to perform data aggregation based on groups. The groups are made by defining a set of attributes that the engine will use to split the data.

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Learning Corner #5 – Logical Query Processing 101

One thing I believe it’s important for everyone who is interested in the database business is the way logical query processing works. And it’s interesting to observe that even some experienced developers have problems interpreting how a query gets processed by SQL Server. In this article, I intend to explain the best I can how Read More