What is the test for showing of good cause in a civil case?

showing of good cause is measured by 'relatively relaxed standards' that serve to 'insure the production' for trial court review of 'all potentially relevant documents.' [Citation.] If the defendant establishes good cause, the court must review the requested records in camera to determine what information, if any, should be disclosed. [Citation.] Subject to certain statutory exceptions and limitations [citation], 'the trial court should then disclose to the defendant "such information [that] is relevant to the subject matter involved in the pending litigation."'" (People v. Gaines (2009) 46 Cal.4th 172, 179 (Gaines).)