Re: SELECT FOR UDPATE behavior inside joins

> Since the CTE has FOR UPDATE, it blocks and returns the updated-by-S1
> version of the row.  But the outer query initially reads the old
> version of the row, so the join condition fails, and we never get
> to the lock-row-and-recheck behavior of UPDATE.

I see, thanks.

> I am not sure what you are hoping to accomplish with that self-join.
> I suppose this is an oversimplified example, but it's too
> oversimplified for anyone to see why you'd want to do it like that.

I was original trying to build a generic way for fetching old rows in

UPDATE RETURNING clause for pre-18 versions but the self join does

not work well with concurrent updates either resulting in lost updates

or not returning the concurrently updated value in RETURNING.

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Thanks,

Tanzeel