On Mon, Oct 25, 2021 at 09:50:01AM +0200, Ronan Dunklau wrote: > Le lundi 25 octobre 2021, 09:40:10 CEST Michael Paquier a écrit : >> On Mon, Oct 25, 2021 at 09:15:32AM +0200, Ronan Dunklau wrote: >>> Does it make sense though ? The NULL slot_name case handling is pretty >>> straight forward has it will be handled by string formatting, but in the >>> case of a null restart_lsn, we have no way of knowing if the command was >>> issued at all. >> >> If I am following your point, I don't think that it matters much here, >> and it seems useful to me to be able to pass NULL for both of them, so >> as one can check if the slot exists or not with an API designed this >> way. > > You're right, but I'm afraid we would have to check the server version twice > in any case different from the basic pg_receivewal on (once in the function > itself, and one before calling it if we want a meaningful result). Maybe we > should move the version check outside the GetSlotInformation function to > avoid > this, and let it fail with a syntax error when the server doesn't support it ?
With the approach taken by the patch, we fall down silently to the previous behavior if we connect to a server <= 14, and rely on the new behavior with a server >= 15, ensuring compatibility. Why would you want to make sure that the command is executed when we should just enforce that the old behavior is what happens when there is a slot defined and a backend <= 14? -- Michael
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