What are the factors used in determining whether a party is necessary and/or indispensable?

The subdivision (b) factors "are not arranged in a hierarchical order." (County of San Joaquin v. State Water Resources Control Bd. (1997) 54 Cal.App.4th 1144, 1149.) No single factor is dispositive, and the court's consideration of the factors is fact-dependent. (City of San Diego, supra, 186 Cal.App.4th at p. 84.) " 'Whether a party is necessary and/or indispensable is a matter of trial court discretion in which the court weighs "factors of practical realities and other considerations." ' " (Ibid.)