Expand description
Manual zerompk wire format for SqlExpr.
Each variant encodes as an array [tag_u8, field1, field2, ...]. Tags
are stable and MUST NOT be renumbered — they are on-wire values in
physical-plan envelopes. Value, BinaryOp, and CastType implement
zerompk natively so they nest transparently.
Tags: Column=0, Literal=1, BinaryOp=2, Negate=3, Function=4, Cast=5, Case=6, Coalesce=7, NullIf=8, IsNull=9, OldColumn=10, ExcludedColumn=11.