Coarse-grained vs fine-grained

Question

From Wikipedia (granularity):

Granularity is the extent to which a system is broken down into small parts, either the system itself or its description or observation. It is the extent to which a larger entity is subdivided. For example, a yard broken into inches has finer granularity than a yard broken into feet.

Coarse-grained systems consist of fewer, larger components than fine-grained systems; a coarse-grained description of a system regards large subcomponents while a fine-grained description regards smaller components of which the larger ones are composed.

In simple terms

• Coarse-grained - larger components than fine-grained, large subcomponents. Simply wraps one or more fine-grained services together into a more coarse­-grained operation.
• Fine-grained - smaller components of which the larger ones are composed, lower­level service

It is better to have more coarse-grained service operations, which are composed by fine-grained operations

Coarse-grained: A few ojects hold a lot of related data that's why services have broader scope in functionality. Example: A single "Account" object holds the customer name, address, account balance, opening date, last change date, etc. Thus: Increased design complexity, smaller number of cells to various operations

Fine-grained: More objects each holding less data that's why services have more narrow scope in functionality. Example: An Account object holds balance, a Customer object holds name and address, a AccountOpenings object holds opening date, etc. Thus: Decreased design complexity , higher number of cells to various service operations. These are relationships defined between these objects.

One more way to understand would be to think in terms of communication between processes and threads. Processes communicate with the help of coarse grained communication mechanisms like sockets, signal handlers, shared memory, semaphores and files. Threads, on the other hand, have access to shared memory space that belongs to a process, which allows them to apply finer grain communication mechanisms.

Source: Java concurrency in practice

In term of dataset like a text file ,Coarse-grained meaning we can transform the whole dataset but not an individual element on the dataset While fine-grained means we can transform individual element on the dataset.