Nice!

Reviewed 3 of 3 files at r1, all commit messages.
Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @mgartner and @rharding6373)

pkg/sql/opt/norm/inline_funcs.go line 440 at r1 (raw file):

	// argForParam returns the argument that can be substituted for the given
	// column, if the column is a parameter of the UDF. It returns ok=false if
	// the column is not a UDF parameter.

Nice, your work to disambiguate parameters and arguments is paying off here.

pkg/sql/opt/norm/inline_funcs.go line 481 at r1 (raw file):

		&memo.SubqueryPrivate{
			OriginalExpr: nil,
			Ordering:     ordering,

[nit] Is it necessary to propagate an ordering here, since the input is guaranteed to return at most one row? Any required ordering should already be preserved by the limit, right?

[also nit] why explicitly set OriginalExpr here?

pkg/sql/opt/norm/testdata/rules/inline line 1149 at r1 (raw file):

 │         └── "?column?":13 = 100 [outer=(13), constraints=(/13: [/100 - /100]; tight), fd=()-->(13)]
 └── projections
      └── (i:2 + 20) + 10 [as=add:20, outer=(2), immutable]

Why isn't this folded into i + 30? Just don't have a rule for it I guess?

Reviewable status: complete! 2 of 0 LGTMs obtained (waiting on @mgartner)

TFTRs!

bors r+

Reviewable status: complete! 0 of 0 LGTMs obtained (and 2 stale) (waiting on @DrewKimball)

pkg/sql/opt/norm/inline_funcs.go line 440 at r1 (raw file):

🎉

pkg/sql/opt/norm/inline_funcs.go line 481 at r1 (raw file):
You're right, the Limit maintains the ordering. This might change when we support set-returning UDFs, so I've left some TODOs for now so we don't forget.

[also nit] why explicitly set OriginalExpr here?

Good catch. That was just leftover; I've removed it.

pkg/sql/opt/norm/testdata/rules/inline line 1149 at r1 (raw file):

Ya, there's not a rule for it:

defaultdb> EXPLAIN (OPT) SELECT i+10+20 FROM generate_series(1, 5) g(i);
                  info
-----------------------------------------
  project
   ├── project-set
   │    ├── values
   │    │    └── ()
   │    └── zip
   │         └── generate_series(1, 5)
   └── projections
        └── (generate_series + 10) + 20
(8 rows)

add(10, add(i, 200)) = 100 would be normalized (in a project or filter) though because we have NormalizeCmpPlusConstwhich would fire twice.