On Wed, 21 Oct 2026 14:43:04 +0800, Keyerror Smart <[email protected]> wrote: > Hi Greg Burd, > Thanks for the review and the +1, and glad to hear you ran into the > same issue. > Regards, > Zhenglong Li
Happy to help out Zhenglong, now we just need to get the attention of a committer who has interest in a fix like this. They are quite busy at the moment, so let's be patient. -greg > Greg Burd <[email protected]> 于2026年10月21日周三 02:56写道： > > > > > On Monday, August 24th, 2026 at 6:13 AM, Keyerror Smart < > > [email protected]> wrote: > > > > > Hi, while testing JSON PASSING, I ran into a minor strictness handling > > bug. > > > > > > JsonExpr is implicitly treated as a strict node in > > contain_nonstrict_functions_walker(), but it > > > isn't actually strict with respect to its PASSING arguments. For > > instance: > > > ```sqlSELECT v FROM (VALUES (1)) a > > > LEFT JOIN (SELECT json_value('1', '$' PASSING y AS p) v > > > FROM (VALUES (1),(2)) b(y)) ss ON false; > > > -- Return 1, not correct > > > > > > -- pull-up plan > > > EXPLAIN (COSTS OFF) > > > SELECT v FROM (VALUES (1)) a > > > LEFT JOIN (SELECT json_value('1', '$' PASSING y AS p) v > > > FROM (VALUES (1),(2)) b(y)) ss ON false; > > > QUERY PLAN > > > ------------------------------------ > > > Nested Loop Left Join > > > Disabled: true > > > Join Filter: false > > > -> Result > > > -> Result > > > Replaces: Scan on *VALUES* > > > One-Time Filter: false > > > Optimizer: Postgres-based planner > > > (8 rows) > > > > > > -- Using OFFSET 0 to prevent pulling up > > > SELECT v FROM (VALUES (1)) a > > > LEFT JOIN (SELECT json_value('1', '$' PASSING y AS p) v > > > FROM (VALUES (1),(2)) b(y) OFFSET 0) ss ON false; > > > -- Return NULL, correct > > > ``` > > > > > > Fix by treating JsonExpr as non-strict, as we already do for CASE, > > > COALESCE and similar constructs. This is conservative -- a JsonExpr > > > with no PASSING arguments and constant ON EMPTY / ON ERROR behaviors > > > is in fact strict -- but distinguishing those cases hardly seems worth > > > the trouble. > > > > > > Patch attached. > > > > > > Regards, > > > Zhenglong Li > > > > Hello Zhenglong Li, > > > > I just happened upon this same issue yesterday in my testing. I was about > > to start a thread when I found yours so I reviewed your patch. > > > > The diagnosis is right, JsonExpr is not strict with respect to its PASSING > > arguments, so treating it as non-strict in > > contain_nonstrict_functions_walker() > > is the correct call, and matching CASE/COALESCE seems to me to be the > > natural > > place for it. > > > > So +1 from me on the approach and the patch. The conservative choice seems > > right, that case is rare and the cost of getting it wrong is a wrong > > answer. > > > > best. > > > > -greg > >
