Expand description
EXPLAIN support for MIR structures.
The specialized Explain implementation for an MirRelationExpr
wrapped in an Explainable newtype struct allows us to interpret more
mz_repr::explain::ExplainConfig options. This is the case because
Analysis derivation and Let normalization are defined in mz_transform
and consequently are not available for the default Explain
implementation for MirRelationExpr in mz_expr.