Before I proceed with coding, I kindly request your insights on a specific scenario I am trying to address.
Despite reviewing numerous MongoDB documents and forums, I still seek clarity on how certain operations would be executed in my unique situation.
The fundamental task at hand involves performing a Read (findOne) operation on a document within a collection residing in its own shard. This is followed by modifying the document's value and then storing it back using findOneAndUpdate. While this may seem straightforward, there lies a challenge where the document might get altered by another write operation during the delay between reading and updating.
To provide context, I am working on a stock market application where each user has a portfolio detailing their stock holdings including the ticker symbol, number of shares owned, and historical total cost. The complexity arises when adjusting the total cost proportionally upon selling shares, necessitating the calculation based on current information before updating the document accurately.
The concern here primarily stems from the potential delay between the read and update actions, especially considering simultaneous modifications to the portfolio document by other users carrying out transactions. This raises the question of ensuring perfect concurrency through atomic operations given the requirement to base updates on the most recent state of the document.
I appreciate any suggestions or solutions you might offer for handling such scenarios effectively while maintaining data integrity. Your time and expertise are greatly valued.