adsharma edited a comment on issue #533: URL: https://github.com/apache/arrow-datafusion/issues/533#issuecomment-860999601
I don't have much context about the proposal. Trying to understand things better. Please bear with me. The reason why SQL doesn't have `select * from t version as of n` is that it violates the isolation property in ACID, by allowing a query to read data from two different points in time (or logical sequence numbers if you prefer). Instead, they prefer a flow such as: ``` BEGIN // implicitly selects a version and all queries following would read from that version select * from t1 union all select * from t2; COMMIT ``` I can also imagine a variant such as: ``` BEGIN TRANSACTION @n1 ... COMMIT ``` which has the same effect. The benefit of these variants is that it makes it harder to write SQL that violates isolation properties. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
