## 49.4. Examples

The PostgreSQL source distribution includes several examples of index methods implemented using GiST. The core system currently provides R-Tree equivalent functionality for some of the built-in geometric data types (see `src/backend/access/gist/gistproc.c`). The following `contrib` modules also contain GiST operator classes:

btree_gist

  B-Tree equivalent functionality for several data types

cube

  Indexing for multi-dimensional cubes

intarray

  RD-Tree for one-dimensional array of int4 values

ltree

  Indexing for tree-like structures

pg_trgm

  Text similarity using trigram matching

seg

  Indexing for “float ranges”

tsearch2

  Full text indexing