Richard Guo <[email protected]> 于2026年1月28日周三 14:42写道： > > On Tue, Jan 27, 2026 at 4:10 PM Richard Guo <[email protected]> wrote: > > On Tue, Jan 27, 2026 at 11:32 AM Tender Wang <[email protected]> wrote: > > > But I found that the case "x IS DISTINCT FROM NULL" is converted to > > > NullTest in transformAExprDistinct(). > > > It will be optimized in the "case T_NullTest:" not by this patch. > > > Well, while it's true that the parser would do this transformation for > > "literal" NULLs, here we are talking more about "calculated" NULLs. > > Consider "not_null_col IS DISTINCT FROM (1 + NULL)". > > BTW, this reminds me that we can teach const-folding to always > transform "x IS [NOT] DISTINCT FROM NULL" to a NullTest, even when x > cannot be proven non-nullable. (The parser have already done that for > literal NULLs.)
Yeah, this transformation can enable the planner to reduce outer joins to plain joins. > Please see 0003 for the details of this transformation. The v3 patches LGTM. -- Thanks, Tender Wang
