What is considered the default standard index type in PostgreSQL?

In PostgreSQL, the default standard index type is the B-tree index. It is used for most comparison and sorting operations, such as =, <, <=, >, >=. The B-tree index is well-suited for fast key lookups and supports uniqueness, making it a versatile choice for most cases.

Example of creating a B-tree index (explicitly, although it is created by default):

CREATE INDEX idx_example ON table_name USING btree(column_name);