Explain PostgreSQL indexing and different types of indexes.

PostgreSQL indexes improve query performance by creating efficient data access paths.

Index Types:

B-tree (Default):
• Best for equality and range queries
• Supports sorting operations

Hash:
• Only for equality comparisons
• Faster than B-tree for simple lookups

GiST (Generalized Search Tree):
• For geometric data types
• Full-text search

GIN (Generalized Inverted Index):
• For composite values (arrays, JSON)
• Full-text search

BRIN (Block Range Index):
• For very large tables
• Stores min/max values per block