PostgreSQL – Index Types
Indexes are essential tools in PostgreSQL, allowing you to speed up data retrieval and enhance the performance of the queries. This article will explore the various index types available in PostgreSQL, understand their unique characteristics, and learn how to use them effectively to optimize your database performance.
PostgreSQL has 6 primary index types:
Table of Content
Let’s discuss each of these index types in detail.
1. B-tree indexes
B-tree is a self-balancing tree that maintains sorted data and allows searches, insertions, deletions, and sequential access in logarithmic time.
PostgreSQL query planner will consider using a B-tree index whenever index columns are involved in a comparison that uses one of the following operators:
- <
- <=
- =
- >=
- BETWEEN
- IN
- IS NULL
- IS NOT NULL
In addition, the query planner can use a B-tree index for queries that involve a pattern matching operator LIKE and ~ if the pattern is a constant and is anchor at the beginning of the pattern.
Example:
column_name LIKE 'foo%' column_name LIKE 'bar%' column_name ~ '^foo'
Furthermore, the query planner will consider using B-tree indexes for ILIKE and ~* if the pattern starts with a non-alphabetic character which are the characters that are not affected by upper/lower case conversion.
2. Hash indexes
Hash indexes can handle only simple equality comparison (=). It means that whenever an indexed column is involved in a comparison using the equal(=) operator, the query planner will consider using a hash index.
To create a hash index, you use the CREATE INDEX statement with the HASH index type in the USING clause as follows.
Syntax:
CREATE INDEX index_name ON table_name USING HASH (indexed_column);
Hash indexes are particularly useful for columns with unique or highly selective values.
3. GIN indexes
GIN stands for Generalized Inverted Indexes. It is commonly referred to as GIN. GIN indexes are most useful when you have multiple values stored in a single column, for example, hstore, array, jsonb, and range types.
4. BRIN
BRIN stands for Block Range INdexes. BRIN is much smaller and less costly to maintain in comparison with a B-tree index. BRIN allows the use of an index on a very large table that would previously be impractical using B-tree without horizontal partitioning. BRIN is often used on a column that has a linear sort order, for example, the ‘created_date’ column of the sales order table.
5. GiST Indexes
GiST stands for Generalized Search Tree. GiST indexes allow a building of general tree structures. GiST indexes are useful in indexing geometric data types and full-text search. They are highly flexible and allow developers to create custom indexing strategies.
6. SP-GiST Indexes
SP-GiST stands for Space-Partitioned Generalized Search Tree. SP-GiST supports partitioned search trees that facilitate the development of a wide range of different non-balanced data structures. SP-GiST indexes are most useful for data that has a natural clustering element to it and is also not an equally balanced tree, for example, GIS, multimedia, phone routing, and IP routing.
Conclusion
In conclusion, Indexes are powerful tools in PostgreSQL, designed to enhance query performance and optimize data retrieval. By understanding the different types of indexes—B-tree, Hash, GIN, BRIN, GiST, and SP-GiST—you can make informed decisions on which index to use based on your specific needs. Implementing the right indexing strategies can significantly improve your database performance, ensuring faster and more efficient access to your data.
