Indexes can also be used to enforce uniqueness of a column's value, or the uniqueness of the combined values of more than one column.

An index column need not be just a column of the underlying table, but can be a function or scalar expression computed from one or more columns of the table. This feature is

Although indexes in PostgreSQL do not need maintenance or tuning, it is still important to check which indexes are actually used by the real-life

An index can be defined on more than one column of a table. For example, if you have a table of this form:

All indexes in PostgreSQL are secondary indexes, meaning that each index is stored separately from the table's main

An index definition can specify an operator class for each column of an index.

A single index scan can only use query clauses that use the index's columns with operators of its operator class and are joined with AND. For example

In addition to simply finding the rows to be returned by a query, an index may be able to deliver them in a specific sorted order. This allows a query's ORDER

PostgreSQL provides several index types: B-tree, Hash, GiST, SP-GiST, GIN and BRIN. Each index type uses a different algorithm that is best

An index can support only one collation per index column. If multiple collations are of interest, multiple indexes may be needed. Consider these