2 answers
Hi ,Use the Database.QueryLocator object when you are using a simple query (SELECT) to generate the scope of objects used in the batch job. If you use a querylocator object, the governor limit for the total number of records retrieved by SOQL queries is bypassed. For example, a batch Apex job for the Account object can return a QueryLocator for all account records (up to 50 million records) in an organization. Another example is a sharing recalculation for the Contact object that returns a QueryLocator for all account records in an organization.THanks,Keyur Modi