Hi all,

The discussion around wCTE during the last week or so has brought to my attention that we don't actually have a consensus on how exactly wCTEs should behave. The question seems to be whether or not a statement should see the modifications of statements ran before it. While I think making the modifications visible would be a lot more intuitive, it's not clear how we'd optimize the execution in the future without changing the behaviour (triggers are a big concern).

I've done some digging today and it seems that IBM's DB2 took the more intuitive approach: all statements are ran, in the order they're written in, to completion before the main statement, materializing the "deltas" into a temporary table and the modifications are made visible to the next statements.

I have no idea how many complaints they have received about this behaviour, but I'd be in favor of matching it.

Thoughts?


Regards,
Marko Tiikkaja

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