This page in other versions: 9.0 / 9.1 / 9.2 / 9.3 / 9.4  |  Development versions: devel  |  Unsupported versions: 7.2 / 7.3 / 7.4 / 8.0 / 8.1 / 8.2 / 8.3 / 8.4

9.5. Locking and Indexes

Though PostgreSQL provides nonblocking read/write access to table data, nonblocking read/write access is not currently offered for every index access method implemented in PostgreSQL.

The various index types are handled as follows:

B-tree indexes

Short-term share/exclusive page-level locks are used for read/write access. Locks are released immediately after each index tuple is fetched or inserted. B-tree indexes provide the highest concurrency without deadlock conditions.

GiST and R-tree indexes

Share/exclusive index-level locks are used for read/write access. Locks are released after the statement (command) is done.

Hash indexes

Share/exclusive page-level locks are used for read/write access. Locks are released after the page is processed. Page-level locks provide better concurrency than index-level ones but are liable to deadlocks.

In short, B-tree indexes are the recommended index type for concurrent applications.

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group