Created a District domain

I want to process millions of accounts. I want to read 1K accounts (pageSize) per DB read, call a REST service in processor with 20 account id’s per call, then write to network storage (recommends fewer writes with lots of data per write) in writer.
I am thinking two options:-

I want to process millions of accounts. I want to read 1K accounts (pageSize) per DB read, call a REST service in processor with 20 account id’s per call, then write to network storage (recommends fewer writes with lots of data per write) in writer.
I am thinking two options:-

I want to process millions of accounts. I want to read 1K accounts (pageSize) per DB read, call a REST service in processor with 20 account id’s per call, then write to network storage (recommends fewer writes with lots of data per write) in writer.
I am thinking two options:-

I want to process millions of accounts. I want to read 1K accounts (pageSize) per DB read, call a REST service in processor with 20 account id’s per call, then write to network storage (recommends fewer writes with lots of data per write) in writer.
I am thinking two options:-

I need some advice on how chunks based approach can be used on my ITEM READER.

I’ve inherited a Spring Batch job & am trying to understand the following behavior.

I am trying to read from table and dump the data in file