Podcast
Questions and Answers
What is a common underlying data structure of most indexes in MySQL?
What is a common underlying data structure of most indexes in MySQL?
What is a characteristic of a covering index?
What is a characteristic of a covering index?
What can be indexed in MySQL, apart from a column?
What can be indexed in MySQL, apart from a column?
What is a benefit of creating an index on a portion of a column?
What is a benefit of creating an index on a portion of a column?
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What is the purpose of making an index invisible before dropping it?
What is the purpose of making an index invisible before dropping it?
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What is the primary purpose of indexing in a database?
What is the primary purpose of indexing in a database?
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What is maintained by each index?
What is maintained by each index?
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Why is it important to strike a balance when creating indexes?
Why is it important to strike a balance when creating indexes?
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What is the relationship between an index and the primary data structure?
What is the relationship between an index and the primary data structure?
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What should you consider when deciding which indexes to create?
What should you consider when deciding which indexes to create?
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Study Notes
B+ Trees and Indexes in MySQL
- B+ trees are the underlying data structure of most indexes in MySQL.
- A secondary key in MySQL is any key (or index) that is not the primary key, but has a special relationship to the primary key.
Creating Indexes
- Indexes can be created on a single column or across multiple columns, with the latter showing more power in indexing.
- Indexing only a portion of a column can lead to smaller indexes with no loss in selectivity, depending on the data.
- A covering index is a regular index in a special situation, and is perhaps the fastest way to satisfy a query.
- Indexes can be created on a function, which is helpful when indexing something that can't quite be reached.
- It is possible to index particular keys in JSON columns, as indexing an entire JSON column is not possible in MySQL.
Characteristics of Indexes
- Indexes maintain a copy of part of the data, with each index having a pointer back to the row.
- Creating multiple indexes means having multiple copies of different parts of the data.
- The key to creating indexes is to strike a balance between creating as many as needed and as few as possible, considering factors like database size, update frequency, and performance impact.
Importance of Indexes
- Indexes are ten times more important than schema design for performance, and maybe even a hundred times more important.
- Indexing is crucial for a high-performing application, as it ensures queries perform well.
Dropping Indexes and Full-Text Searching
- Dropping an index can be scary, but making it invisible first can help test the ramifications on the application.
- FULLTEXT indexes can be used to search across multiple columns, unlocking new search capabilities and optimizing databases.
- Mastering full-text searching with MySQL can be beneficial.
Foreign Keys and Composite Indexes
- Foreign keys and foreign key constraints are related but not the same.
- Composite indexes can lead to redundant indexes, which can occur when some indexes are not used.
Introduction to Indexing
- Indexing is the best way to ensure query performance, which is essential for a high-performing application.
- Understanding access patterns is crucial when deciding which indexes to create.
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Description
Learn about B+ trees, secondary keys, and how to determine where to add indexes in MySQL. Understand the importance of index selectivity and how to create effective indexes.
