When I run "EXPLAIN JSON", one of the things I get back is "COST_STATUS". I have looked in the documentation but can't find what it means, does anyone know anything about this?
COST_STATUS explains whether the cost is based on good statistics or not. Other than "GOOD", it can be NO_STATISTICS (self evident) or PREDICATE VALUE OUT-OF-RANGE (estimated predicate selectivity due to stale statistics). The value not being GOOD doesn't necessarily mean the plan is bad, merely that it was based on (more) guesswork by the optimizer.