Oracle DB Transactions — Fuzzy Read
Nov 13, 2020
Non-repeatable or fuzzy read: Transaction T1 reads a data item. Another transaction T2 then modifies or deletes that data item and commits. If T1 then attempts to reread the data item, it receives a modified value or discovers that the data item has been deleted.
r1[x]…w2[x]…c2…r1[x]…c1
💡 How to read the shorthand notations? w means write, r means read, number(1 or 2) indicates transaction id, c means commit and a means abort/rollback
💡Serializable isolation level in Oracle is actually a “Snapshot Isolation”
Transaction 1
Transaction 2
Transaction 2