如何優化具有左硬連接的查詢？

Question

我有一個查詢

SELECT 
"athlete"."id" AS "athlete_id" 
FROM "athlete" 
LEFT JOIN "athlete_in_game" ON athlete.id = athlete_in_game.id_athlete 
LEFT JOIN "athlete_in_team" ON athlete.id = athlete_in_team.id_athlete 
LEFT JOIN "game" ON 
    athlete_in_team.id_team = game.id_team_home OR 
    athlete_in_team.id_team = game.id_team_away OR 
    athlete_in_game.id_game = game.id 
LEFT JOIN "sport_competition" ON sport_competition.id_game = game.id 
GROUP BY "athlete"."id" 

我需要選擇其在比賽中發揮所有的運動員。但可能是因爲幾場比賽沒有數據在表格「運動員在線遊戲」中，並且在這種情況下，我會從表「athlete_in_team」中的所有運動員參加這些遊戲。正因爲如此，我在第三個左連接中使用雙「OR」。我需要所有書面條件，但由於雙「或」，它可能會工作太久。無論如何，是否有機會優化它？

Answer 1

我認爲首先你必須首先改善模式。團隊相關信息應該是單獨的表格。和遊戲應該是分開的。你不需要和我想的game表左邊加入。只有加入athlete_in_game和athlete_in_team就足夠了。像這樣

SELECT 
"athlete"."id" AS "athlete_id" 
FROM "athlete" 
LEFT JOIN "athlete_in_game" ON athlete.id = athlete_in_game.id_athlete 
LEFT JOIN "athlete_in_team" ON athlete.id = athlete_in_team.id_athlete 
JOIN "game" ON 
    athlete_in_team.id_team = game.id_team_home OR 
    athlete_in_team.id_team = game.id_team_away OR 
    athlete_in_game.id_game = game.id 
LEFT JOIN "sport_competition" ON sport_competition.id_game = game.id 
GROUP BY "athlete"."id"