Berkeley DB

Page Locks

With the exception of the Queue access method, the access methods use page-level locking. The size of pages a database has may be set when the database is created by calling the DB→set_pagesize function. If not specified by the application, Berkeley DB selects a page size that will provide the best I/O performance by setting the page size equal to the block size of the underlying file system. Selecting a smaller page size can result in increased concurrency for some applications.

In the Btree access method, Berkeley DB uses a technique called lock-coupling to improve concurrency. The traversal of a Btree requires reading a page, searching that page to determine which page to search next, and then repeating this process on the next ...