Two schedules S1 and S2 are said to be view equal if below conditions are satisfied :
1) Initial Read
If a transaction T1 reading data item A from initial database in S1 then in S2 also T1 should read A from initial database.
T1 T2 T3 ------------------- R(A) W(A) R(A) R(B)
Transaction T2 is reading A from initial database.
If Ti is reading A which is updated by Tj in S1 then in S2 also Ti should read A which is updated by Tj.
T1 T2 T3 T1 T2 T3 ------------------- ---------------- W(A) W(A) W(A) R(A) R(A) W(A)
Above two schedule are not view equal as in S1 :T3 is reading A updated by T2, in S2 T3 is reading A updated by T1.
3)Final Write operation
If a transaction T1 updated A at last in S1, then in S2 also T1 should perform final write operations.
T1 T2 T1 T2 ------------ --------------- R(A) R(A) W(A) W(A) W(A) W(A)
Above two schedule are not view as Final write operation in S1 is done by T1 while in S2 done by T2.
View Serializability: A Schedule is called view serializable if it is view equal to a serial schedule (no overlapping transactions).
Below are the previous Year Gate Question asked on this topic
Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above
Attention reader! Don’t stop learning now. Get hold of all the important CS Theory concepts for SDE interviews with the CS Theory Course at a student-friendly price and become industry ready.
- Difference between Conflict and View Serializability
- Conflict Serializability in DBMS
- Precedence Graph For Testing Conflict Serializability in DBMS
- Result Serializability in DBMS
- Concurrency problems in DBMS Transactions
- Lightweight Transactions in Cassandra
- Recovery With Concurrent Transactions
- Polygraph to check View Serializabilty in DBMS
- Check if Table, View, Trigger, etc present in Oracle
- Difference between Simple and Complex View in SQL
- What is GAV (Global as View)?
- Difference between View and Cursor in SQL
- Local as View (LAV)
- Lossless Decomposition in DBMS
- Introduction of Relational Algebra in DBMS
- Need for DBMS
- Commonly asked DBMS interview questions | Set 1
- Normal Forms in DBMS
- Relational Model in DBMS
- Commonly asked DBMS interview questions | Set 2
Improved By : AmolBarge