Module expr::explain[][src]

Expand description

This module houses a pretty printer for MirRelationExprs.

Format details:

  • The nodes in a MirRelationExpr are printed in post-order, left to right.
  • Nodes which only have a single input are grouped together into “chains.”
  • Each chain of MirRelationExprs is referred to by ID, e.g. %4.
  • Nodes may be followed by additional, indented annotations.
  • Columns are referred to by position, e.g. #4.
  • Collections of columns are written as ranges where possible, e.g. “#2..#5”.

It’s important to avoid trailing whitespace everywhere, as plans may be printed in contexts where trailing whitespace is unacceptable, like sqllogictest files.

Structs

Pretty-prints a list of indices.

An ViewExplanation facilitates pretty-printing of a MirRelationExpr.