Batch Apex Quick Notes For Interview

Batch Apex:

Used for large data sets(more than 10K)
Each transaction starts with a new set of governor limits
If one batch fails, all other successful batch are not rolled back
Default size is 200 and max is 2000
We have to write 3 method start(), execute() and finish() because we use Database.Batchable Interface and we can’t skip any method of interface whether the method having any body or not
Query locator:
- 50 million records can be returned
- Can’t use aggregate queries
Iterable:
- Governor limits will be enforced 50000 records
Stateless
5 can be active concurrently
We can call a batch class from trigger
Batch class can’t call a future method
We can call a batch class inside other batch class in finish method
If we want to call in execute method then we need to use Queueable class
Use Database.Callouts interface to make callouts in batch class.