Related Work

Parallel DBMS (Shared Disk)

• Object Locks for serializing. Locks are strict 2PL.
• Physical locks can be released during transactions or they can be held across transactions.
• Page Locks for Cache Coherence, short term (Pin)
• Allow a page to be kept in shared (read only) mode at multiple sites and to ensure that only one site at a time can gain write access to the page.
• To update a page, the site has to be the owner of the page. When a different site wishes to update the page, it must be sent the most recent page by the current owner.