Can a defendant withdraw a guilty or no contest plea before judgment?

A defendant seeking to withdraw a guilty or no contest plea may do so before judgment upon a showing of good cause pursuant to section 1018. "Although section 1018 is limited on its face to the period before judgment, the courts have long permitted defendants to move to set aside the judgment as a means of allowing the defendant to withdraw the guilty plea after judgment." (People v. Castaneda (1995) 37 Cal.App.4th 1612, 1617.) Such a postjudgment motion to withdraw a plea requires the defendant to make "a showing essentially identical to that required under Penal Code section 1018." (Ibid.)