Index access methods must handle concurrent updates of the index by multiple processes. The core PostgreSQL system obtains

In an index scan, the index access method is responsible for regurgitating the TIDs of all the tuples it has been told about that match the scan keys

PostgreSQL enforces SQL uniqueness constraints using unique indexes, which are indexes that disallow multiple entries

The index construction and maintenance functions that an index access method must provide in IndexAmRoutine are:

The amcostestimate function is given information describing a possible index scan, including lists of WHERE and ORDER BY clauses that have been

Each index access method is described by a row in the pg_am