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Displaying posts with tag: range lookup (reset)
Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5

This is the second blog post in the series of blog posts leading up to the talk comparing the optimizer enhancements in MySQL 5.6 and MariaDB 5.5. This blog post is aimed at the optimizer enhancement Multi Range Read (MRR). Its available in both MySQL 5.6 and MariaDB 5.5

Now let’s take a look at what this optimization actually is and what benefits it brings.

Multi Range Read

With traditional secondary index lookups, if the columns that are being fetched do not belong to the secondary index definition (and hence covering index optimization is not used), then primary key lookups have to be performed for each secondary key entry fetched. This means that secondary key lookups for column values that do not belong to the secondary index definition can result in a lot of Random I/O. The …

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Understanding B+tree Indexes and how they Impact Performance

Indexes are a very important part of databases and are used frequently to speed up access to particular data item or items. So before working with indexes, it is important to understand how indexes work behind the scene and what is the data structure that is used to store these indexes, because unless you understand the inner working of an index, you will never be able to fully harness its power.

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