Tom Lane 215824f918 In postgres_fdw, don't try to ship MULTIEXPR updates to remote server. ... In a statement like "UPDATE remote_tab SET (x,y) = (SELECT ...)", we'd conclude that the statement could be directly executed remotely, because the sub-SELECT is in a resjunk tlist item that's not examined for shippability. Currently that ends up crashing if the sub-SELECT contains any remote Vars. Prevent the crash by deeming MULTIEXEC Params to be unshippable. This is a bit of a brute-force solution, since if the sub-SELECT *doesn't* contain any remote Vars, the current execution technology would work; but that's not a terribly common use-case for this syntax, I think. In any case, we generally don't try to ship sub-SELECTs, so it won't surprise anybody that this doesn't end up as a remote direct update. I'd be inclined to see if that general limitation can be fixed before worrying about this case further. Per report from Lukáš Sobotka. Back-patch to 9.6. 9.5 had MULTIEXPR, but we didn't try to perform remote direct updates then, so the case didn't arise anyway. Discussion: https://postgr.es/m/CAJif3k+iA_ekBB5Zw2hDBaE1wtiQa4LH4_JUXrrMGwTrH0J01Q@mail.gmail.com		2020-01-26 14:31:08 -05:00
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postgres_fdw.sql	In postgres_fdw, don't try to ship MULTIEXPR updates to remote server.	2020-01-26 14:31:08 -05:00