How many times in total did the team Boston Red Stockings participate in postseason games?
SELECT count(*) FROM ( SELECT * FROM postseason AS T1 JOIN team AS T2 ON T1.team_id_winner  =  T2.team_id_br WHERE T2.name  =  'Boston Red Stockings' UNION SELECT * FROM postseason AS T1 JOIN team AS T2 ON T1.team_id_loser  =  T2.team_id_br WHERE T2.name  =  'Boston Red Stockings' );
team Boston Red Stockings participate in postseason games refers to counting instances where Boston Red Stockings is either a winner or a loser in post season games; UNION is used to combine the results of two SELECT queries; count(*) is used to count the total number of times.