Re: [HACKERS] Fixing matching of boolean index columns to sort ordering

Every WHERE clause is a

boolean expression, so there's no principled reason why such a rule
wouldn't result in canonicalizing e.g. "i = 42" into "(i = 42) = true",
wreaking havoc on every other optimization we have.  Restricting it
to only apply to simple boolean columns is no answer because (a) indexes
can be on boolean expressions not just simple columns, and (b) part
of the point of the canonicalization is to make logically-equivalent
expressions look alike, so declining to apply it in some cases would
ruin that.