How Can I Resolve SQLAlchemy\'s Caching Issues and Ensure Data Reflects Changes Immediately?

Understanding and Disabling Caching in SQLAlchemy

In the realm of database interactions, SQLAlchemy occasionally raises the issue of perceived caching. This occurs when data inserted or updated through SQLAlchemy doesn't immediately reflect changes made outside of its scope. While SQLAlchemy employs a local identity map within transactions, the primary culprit is often the effects of transaction isolation.

SQLAlchemy's session operates in a transactional manner by default. Changes are not persisted to the database until session.commit() is invoked. During this period, concurrent transactions will not observe these modifications. However, the isolation nature of transactions introduces an additional layer of complexity.

Transactions in progress not only remain unaware of uncommitted changes, but they also may not recognize them even after they commit or roll back. This is due to the concept of repeatable reads. In this scenario, transactions retain their initial snapshot of the data, preventing them from reflecting subsequent changes made in other transactions.

To disable this isolation behavior and force SQLAlchemy to retrieve the latest data, it is necessary to adjust the transaction isolation level of the database connections. This can be achieved by setting the isolation_level parameter in the database engine's configuration. By lowering the isolation level, such as setting it to "READ COMMITTED," concurrent transactions will be able to observe committed changes.

It is important to note that reducing isolation levels can introduce potential concurrency issues. Carefully consider the trade-offs between data consistency and performance before making any changes.

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