January 9, 2023 By Matthew Rathbone *

To create an index in Postgresql, you can use the CREATE INDEX statement. This statement allows you to specify the name of the index, the table and column on which the index is being created, and the type of index.

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CREATE INDEX Syntax

Here is the syntax for creating an index:

CREATE [ UNIQUE ] INDEX index_name
ON table_name ( column1 [, column2, ...] );

To create a unique index, you can include the UNIQUE keyword. This will ensure that no duplicate values are inserted into the indexed column. This is similar to a unique constraint.

CREATE INDEX Example

Once you have specified the index name, table name, and columns, you can execute the statement to create the index. For example, if you want to create an index on the email column of the users table, you can use the following statement:

CREATE INDEX email_index
ON users (email);

This will create an index on the email column of the users table. You can verify that the index has been created by using the \d command in the psql prompt, or by clicking Show Structure in Beekeeper Studio.

Changing The Index Type

You can also specify the type of index to create. Postgresql supports several types of indexes, including B-tree, hash, GiST, and GIN indexes. The default index type is a B-tree index, which is suitable for most use cases. However, if you have specific performance or data type requirements, you can choose a different index type.

To specify the index type, you can use the USING keyword followed by the index type. For example, to create a GiST index on the email column of the users table, you can use the following statement:

CREATE INDEX email_index
ON users USING GIST (email);

Performance Implications

Once the index is created, it will be used by the database to speed up queries that search for data in the indexed column. This can improve the performance of your queries, especially for large tables with millions of rows.

It’s important to note that creating indexes can have a performance impact on writes to the database, as the database must update the index when data is inserted, updated, or deleted. Therefore, you should only create indexes on columns that are frequently searched in your queries.

PostgreSQL CREATE INDEX Summary

In summary, to create an index in Postgresql, you can use the CREATE INDEX statement to specify the index name, table name, and columns. You can also specify the index type using the USING keyword, and use the UNIQUE keyword to create a unique index. Indexes can improve the performance of your queries, but they can also have a performance impact on writes to the database, so use them wisely.