#isolation level

The difference of Isolation level – Read Committed vs Repeatable Read

MySQL’s default isolation level is “Repeatable Read“. But Oracle’s default isolation level is “Read Committed“. In this post, I will show you the difference by example.

Test environment : MySQL 5.7

Test table

create table lock_test( col1 varchar(10), col2 varchar(20), primary key(col1)); insert into lock_test values('1', 'A'); insert into lock_test values('2', 'B'); insert into lock_test…

DB2-Concurrency And Locking Interview Questions

DB2+Mainframe+jobs

I am giving here some challenging interview questions in concurrency and Locking. These questions are asked in many big companies like IBM, Dell, L&T, Allstate, Infosys, Wipro etc.

1). What is concurrency in database environment?

A.  Database system must ensure that data can be accessed concurrently by the users. Access should be granted while guaranteeing integrity of the data…