F2023 #17 - Timestamp Ordering Concurrency Control (CMU Intro to Database Systems)

[@_4_632]

29:20 T/O Concurrency Control 31:25 Timestamp Allocation 32:43 Basic T/O - Every object X is tagged with timestamp of the last txn that successfully did read/write. Check timestamps for every operation. provides building blocks for OCC/MVCC no database actually uses this (performance issues, every read requires the txn to write to the database) 34:35 Basic T/O READS (Don't read stuff from the "future") 37:39 Basic T/O WRITES (Can't write if a future transaction has read or written to the object) 51:10 Thomas Write Rule (in practice it's not really used?) 56:40 Observation 58:49 Optimistic Concurrency Control (dbms creats a private workspace for each txn) 1:00:15 OCC Phases (Read/Validation/Write)

[@changliu9090]

In your lecture of lec 17, T_i completes its Read phase before T_j completes its Read phase, but the video shows us T_i completes its Read phase before T_j starts its Read phase.