About refreshing objects in sqlalchemy session

Question

Well, I am dealing with a doubt about sqlalchemy and objects refreshing!

I am in the situation in what I have 2 sessions, and the same object has been queried in both se

Answer 1

TL;DR Rather than working on Session synchronization, see if your task can be reasonably easily coded with SQLAlchemy Core syntax, directly on the Engine, without the use of (multiple) Sessions

For someone coming from SQL and JDBC experience, one critical thing to learn about SQLAlchemy, which, unfortunately, I didn't clearly come across reading through the multiple documents for months is that SQLAlchemy consists of two fundamentally different parts: the Core and the ORM. As the ORM documentation is listed first on the website and most examples use the ORM-like syntax, one gets thrown into working with it and sets them-self up for errors and confusion - if thinking about ORM in terms of SQL/JDBC. ORM uses its own abstraction layer that takes a complete control over how and when actual SQL statements are executed. The rule of thumb is that a Session is cheap to create and kill, and it should never be re-used for anything in the program's flow and logic that may cause re-querying, synchronization or multi-threading. On the other hand, the Core is the direct no-thrills SQL, very much like a JDBC Driver. There is one place in the docs I found that "suggests" using Core over ORM:

it is encouraged that simple SQL operations take place here, directly on the Connection, such as incrementing counters or inserting extra rows within log tables. When dealing with the Connection, it is expected that Core-level SQL operations will be used; e.g. those described in SQL Expression Language Tutorial.

Although, it appears that using a Connection causes the same side effect as using a Session: re-query of a specific record returns the same result as the first query, even if the record's content in the DB was changed. So, apparently Connections are as "unreliable" as Sessions to read DB content in "real time", but a direct Engine execution seems to be working fine as it picks a Connection object from the pool (assuming that the retrieved Connection would never be in the same "reuse" state relatively to the query as the specific open Connection). The Result object should be closed explicitly, as per SA docs