mysql - 查询三个连接非常慢

Question

我正在尝试返回在特定日期 进行足球比赛 的所有国家/地区。数据在下表中定义:

竞争

id | country_id | name 
50       1         Premier League

competition_seasons

id | competition_id | name
 70       50          2019

competition_rounds

id | season_id | name 
 58       70      Regular Season

匹配

id | round_id | home | away | result | datetime
 44      58       22     87     1 - 0  2019-03-16:00:00

competition表中存储了不同的比赛，然后每个比赛可以有多个season存储在competition_seasons中。一个 season 也可以有不同的比赛 rounds，这些都存储在 competition_rounds 中。

所有匹配都存储在match表中，并根据round_id进行分组。

我为 API 编写了这个方法:

$app->get('/country/get_countries/{date}', function (Request $request, Response $response, array $args)
{
  $start_date = $args["date"] . " 00:00";
  $end_date = $args["date"] . " 23:59";

  $sql = $this->db->query("SELECT n.* FROM country n
    LEFT JOIN competition c ON c.country_id = n.id
    LEFT JOIN competition_seasons s ON s.competition_id = c.id
    LEFT JOIN competition_rounds r ON r.season_id = s.id
    LEFT JOIN `match` m ON m.round_id = r.id
    WHERE m.datetime BETWEEN '" . $start_date . "' AND '" . $end_date . "'
    GROUP BY n.id");

  $sql->execute();
  $countries = $sql->fetchAll();
  return $response->withJson($countries);
});

有数千条记录按 id 组织，但查询需要大约 6、7 秒才能返回指定日期播放的所有国家/地区。

我怎样才能优化这个过程？

性能

更新

如果我这样做的话，我注意到了一件有趣的事情:

SELECT round_id, DATE("2019-03-18") FROM `match`

查询速度非常快，所以我猜 datetime 字段会减慢连接部分的速度，你知道吗？

表结构

CREATE TABLE IF NOT EXISTS `swp`.`competition` (
  `id` INT NOT NULL,
  `country_id` INT NULL,
  `name` VARCHAR(255) NULL,
  `category` INT NULL,
  PRIMARY KEY (`id`),
  INDEX `id_idx` (`country_id` ASC),
  INDEX `FK_competition_types_competition_type_id_idx` (`category` ASC),
  CONSTRAINT `FK_country_competition_country_id`
    FOREIGN KEY (`country_id`)
    REFERENCES `swp`.`country` (`id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION,
  CONSTRAINT `FK_competition_categories_competition_category_id`
    FOREIGN KEY (`category`)
    REFERENCES `swp`.`competition_categories` (`id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB;


CREATE TABLE IF NOT EXISTS `swp`.`competition_seasons` (
  `id` INT NOT NULL AUTO_INCREMENT,
  `competition_id` INT NOT NULL,
  `season_id` INT NULL,
  `name` VARCHAR(45) NOT NULL,
  `update_at` DATETIME NULL,
  PRIMARY KEY (`id`),
  INDEX `FK_competition_competition_seasons_competition_id_idx` (`competition_id` ASC),
  CONSTRAINT `FK_competition_competition_seasons_competition_id`
    FOREIGN KEY (`competition_id`)
    REFERENCES `swp`.`competition` (`id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB;

CREATE TABLE IF NOT EXISTS `swp`.`competition_rounds` (
  `id` INT NOT NULL AUTO_INCREMENT,
  `round_id` INT NULL,
  `season_id` INT NOT NULL,
  `name` VARCHAR(255) NULL,
  PRIMARY KEY (`id`),
  INDEX `FK_competition_seasons_competition_rounds_season_id_idx` (`season_id` ASC),
  CONSTRAINT `FK_competition_seasons_competition_rounds_season_id`
    FOREIGN KEY (`season_id`)
    REFERENCES `swp`.`competition_seasons` (`id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB;

-- -----------------------------------------------------
-- Table `swp`.`match`
-- -----------------------------------------------------
CREATE TABLE IF NOT EXISTS `swp`.`match` (
  `id` INT NOT NULL,
  `round_id` INT NOT NULL,
  `group_id` INT NULL,
  `datetime` DATETIME NULL,
  `status` INT NULL,
  `gameweek` INT NULL,
  `home_team_id` INT NULL,
  `home_team_half_time_score` INT NULL,
  `home_team_score` INT NULL,
  `home_extra_time` INT NULL,
  `home_penalties` INT NULL,
  `away_team_id` INT NULL,
  `away_team_half_time_score` INT NULL,
  `away_team_score` INT NULL,
  `away_extra_time` INT NULL,
  `away_penalties` INT NULL,
  `venue_id` INT NULL,
  `venue_attendance` INT NULL,
  `aggregate_match_id` INT NULL,
  PRIMARY KEY (`id`),
  INDEX `home_team_id_idx` (`home_team_id` ASC),
  INDEX `away_team_id_idx` (`away_team_id` ASC),
  INDEX `venue_id_idx` (`venue_id` ASC),
  INDEX `match_status_id_idx` (`status` ASC),
  INDEX `FK_competition_rounds_match_round_id_idx` (`round_id` ASC),
  INDEX `FK_match_match_aggregate_match_id_idx` (`aggregate_match_id` ASC),
  INDEX `FK_competition_groups_match_group_id_idx` (`group_id` ASC),
  CONSTRAINT `FK_team_match_home_team_id`
    FOREIGN KEY (`home_team_id`)
    REFERENCES `swp`.`team` (`id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION,
  CONSTRAINT `FK_team_match_away_team_id`
    FOREIGN KEY (`away_team_id`)
    REFERENCES `swp`.`team` (`id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION,
  CONSTRAINT `FK_venue_match_venue_id`
    FOREIGN KEY (`venue_id`)
    REFERENCES `swp`.`venue` (`id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION,
  CONSTRAINT `FK_match_status_match_status_id`
    FOREIGN KEY (`status`)
    REFERENCES `swp`.`match_status` (`id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION,
  CONSTRAINT `FK_competition_rounds_match_round_id`
    FOREIGN KEY (`round_id`)
    REFERENCES `swp`.`competition_rounds` (`id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION,
  CONSTRAINT `FK_match_match_aggregate_match_id`
    FOREIGN KEY (`aggregate_match_id`)
    REFERENCES `swp`.`match` (`id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION,
  CONSTRAINT `FK_competition_groups_match_group_id`
    FOREIGN KEY (`group_id`)
    REFERENCES `swp`.`competition_groups` (`id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB;

Answer 1

首先，将查询写成:

SELECT n.*
FROM country n JOIN
     competition c
     ON c.country_id = n.id JOIN
     competition_seasons s
     ON s.competition_id = c.id JOIN
     competition_rounds r
     ON r.season_id = s.id JOIN
     `match` m
     ON m.round_id = r.id
WHERE m.datetime >= ? AND
      m.datetime < ?
GROUP BY n.id;

这里的改动比较小，不会影响性能。但它们很重要:

• JOIN而不是 LEFT JOIN ，因为您要求条件匹配。
• 日期参数而不是修改查询字符串，因为这是个好主意。
• >=和 <用于比较，因为这适用于日期和日期时间。您需要将结束日期增加 1 天，但不要包含时间部分。

然后，为了性能，你需要索引:

• match(datetime, round_id)
• competition_rounds(id, season_id)
• competition_seasons(id, competition_id)
• competition(id, country_id)
• country(id)

其实第一个是最重要的。如果相应的 id 则不需要最后四个列被声明为主键。