The btree_gin extension in PostgreSQL enables GIN indexes to support B-tree indexable data types. It is useful when you want to use a GIN index for multi-column queries that include standard B-tree searchable data types like int, text, timestamp, and uuid. Your Nile database arrives with btree_gin extension already enabled, so there’s no need to run create extension.

​
Creating and Populating a Sample Table

Before creating the index, let’s create a sample table and populate it with data: 
CREATE TABLE my_table (
    id SERIAL PRIMARY KEY,
    column1 TEXT,
    column2 INT,
    column3 TIMESTAMP
);

INSERT INTO my_table (column1, column2, column3) VALUES
    ('apple', 10, '2024-01-01 10:00:00'),
    ('banana', 20, '2024-02-01 11:30:00'),
    ('grape', 15, '2024-03-01 14:15:00'),
    ('orange', 25, '2024-04-01 09:45:00'),
    ('lemon', 30, '2024-05-01 16:20:00');

​
Creating a GIN Index with btree_gin

A GIN index with btree_gin is useful when performing multi-column searches that include B-tree indexable columns. Here’s how to create one: 
CREATE INDEX gin_idx ON my_table
USING gin (column1, column2, column3);
Note: USING gin specifies that this is a GIN index. The extension allows column1 (text), column2 (integer), and column3 (timestamp) to be indexed efficiently using GIN.

​
Querying with GIN Index

Once the GIN index is created, it can be used to optimize queries filtering on indexed columns: 
SELECT * FROM my_table WHERE column1 = 'apple' AND column2 = 10;

​
Limitations

  • GIN indexes are optimized for fast lookups but have slower insert/update performance compared to B-tree indexes.
  • They work best when querying multiple indexed columns together.
  • Unlike B-tree indexes, they do not support range queries efficiently.

​
Removing a GIN Index

If you need to remove a GIN index: 
DROP INDEX gin_idx;

​
Conclusion

The btree_gin extension enhances GIN indexes by allowing them to handle B-tree indexable data types efficiently. It is particularly useful for multi-column indexing scenarios where a mix of text, integer, and timestamp fields are queried together. For more details, refer to the PostgreSQL documentation.