implementing using `find_each` and `pluck` together in Rails for large datasets
I'm currently working on a Rails 6 application where I need to process a large dataset stored in a PostgreSQL database. To improve memory usage, I decided to use `find_each` to paginate through my ActiveRecord query, but I'm running into a question when I try to combine it with `pluck` to retrieve only specific fields. I expected this to work seamlessly, but I'm running into unexpected behavior. Here's the code I've been using: ```ruby User.where(active: true).find_each(batch_size: 1000) do |user| user_ids = User.where(active: true).pluck(:id) # Process user IDs here end ``` I expected `user_ids` to be an array of IDs for the current batch of users being processed, but instead, it's fetching all active users in the database every time, which defeats the purpose of using `find_each` for performance. I've tried isolating the query by using the block variable `user` to limit the processed records, but this still seems to fetch the complete list of active users every time. What I really want is to only work with the subset of users that `find_each` is currently iterating through, but Iām not sure how to achieve that. When I print `user_ids`, I see the following output: ``` [1, 2, 3, ..., 10000] # All active user IDs, not the expected subset ``` Is there a way to modify this approach to ensure I'm only working with the IDs of users in the current batch? Any insights or best practices would be greatly appreciated! I'm working on a service that needs to handle this.