PPT-Lecture 8--Continued: Concurrency & Locking

Lecture 8 Announcements Lecture 8 gt Announcements Scores were quite good overall for homework Were excited Destroy the midterm Midterm is with CAs We will post on the page how to divide into overflow rooms. Slide . 1. Too Much Milk. . Roommate . A. 3:00. Arrive home: no milk. 3:05. Leave for store. 3:10. Arrive at store. 3:15. Leave store. 3:20. Arrive home, put milk away. CS 140 Lecture Notes: Concurrency. LOCKING BAR Big 6 PadlockFortress Locking BarBIG 6 PADLOCKFORTRESS LOCKING BAR CLOSE SHACKLE PADLOCK &NARROWSTYLE LOCKING BAR ERA Close Shackle Padlocklever locking mechanism with a close hardenedfor 1. David . Lomet. Microsoft Research. Mohamed . Mokbel. University of Minnesota. Talk Outline. Unbundled. Transaction Services. Challenge: Key Range Locking. Using. Conventional . L. ocking. . M. anagers. Slide . 1. Too Much Milk. . Person A. 3:00. Arrive home: no milk. 3:05. Leave for store. 3:10. Arrive at store. 3:15. Leave store. 3:20. Arrive home, put milk away. CS 140 Lecture Notes: Concurrency. Sadhna Kumari. OUTLINE. ACID Properties. 2-Phase Commit Protocol. TPS. Serializability. Concurrency Control Protocols. Current Research. Future. References. ACID PROPERTIES. Atomicity: . A . transaction is . evaluating locking schemes in . 2010-02-27. james . francis. toy iv. David . Hemmendinger. Purpose. Evaluate current locking scheme in FreeBSD. See if the locking methods can be improved. Evaluate both methods and form conclusions. 1. David . Lomet. Microsoft Research. Mohamed . Mokbel. University of Minnesota. Talk Outline. Unbundled. Transaction Services. Challenge: Key Range Locking. Using. Conventional . L. ocking. . M. anagers. Database System Implementation CSE 507. Some slides adapted from . Navathe. et. Al. , . Silberchatz. et. Al and . Hector Garcia-Molina . Lock Based Protocols. A lock is a mechanism to control concurrent access to a data item. Concurrency Control. Locking. Atomic statement. Can be used to perform two or more updates atomically. Th1: …. < x = x + 1; y = z>;…….. Th2:………….<m = m + 1;….>;…….. Transactions. Database Concurrency Control. 1 Purpose of Concurrency Control. To enforce Isolation (through mutual exclusion) among conflicting transactions. . To preserve database consistency through consistency preserving execution of transactions.. Introduction. Concurrency control protocols. Set of rules to guarantee serializability. Two-phase locking protocols. Lock data items to prevent concurrent access. Timestamp. Unique identifier for each transaction. Sadhna Kumari. OUTLINE. ACID Properties. 2-Phase Commit Protocol. TPS. Serializability. Concurrency Control Protocols. Current Research. Future. References. ACID PROPERTIES. Atomicity: . A . transaction is . Slide . 1. Too Much Milk. . Roomate. A. 3:00. Arrive home: no milk. 3:05. Leave for store. 3:10. Arrive at store. 3:15. Leave store. 3:20. Arrive home, put milk away. CS 140 Lecture Notes: Concurrency. Some slides adapted from . Navathe. et. Al. , . Silberchatz. et. Al and . Hector Garcia-Molina . Lock Based Protocols. A lock is a mechanism to control concurrent access to a data item. Data items can be locked in two modes :.