Database Index
A database index is a data structure that speeds up reads by letting the database find rows without scanning the whole table, at the cost of extra storage and slower writes.
Indexes work like a book's index: instead of reading every page, the database jumps straight to matching rows. They're essential for fast filtering, sorting, and joins on large tables.
Common index types in PostgreSQL include B-tree (the default, great for equality and ranges), GIN (for full-text and JSON), and partial indexes for subsets of rows.
Indexes also matter for security and performance together — for example, indexing the columns referenced by row-level security policies keeps policy checks fast.
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