INDEXING IN SQL
SQL indexes. What are they? and how can you use them? A book with a table of contents is similar to database with indexes.
SQL indexes can be likened to indexing in books.
SQL indexes are similar to indexes in books. They are like table of contents. Indexes help SQL to quickly find information based on column values. This is faster and more efficient than going through every row in a table and trying to find an information, which can be time-consuming and lead to longer query times.
Types of Indexes:
There are different types of indexes but the 5 most common types are:
Clustered Index:
It controls the physical order of the data in the table.
Only one clustered index per table is allowed.
2. Non-Clustered Index: It creates a separate structure from the table that points to the rows without changing the physical order.
Multiple non-clustered indexes can be created on a table.
3. Unique Index: Ensures that all values in the indexed column are unique, effectively preventing duplicates.
4. Full-Text Index: It’s optimized for searching large amounts of textual data within a column.
5. Composite Index: it’s an index on more than one column that improves query performance when multiple columns are involved in search criteria.
Indexes are powerful tools that enhance the performance of SQL queries, especially when dealing with large datasets. You can drastically improve data retrieval times and ensure database efficiency by strategically choosing between clustered, non-clustered, unique, and other index types. It’s important to use indexes wisely — over-indexing can lead to slower write operations and increased storage requirements. Understanding when and how to use indexes is key to maintaining a balanced, high-performing database.
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Disclaimer: The dataset used in this article is for demonstration purposes only.
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