如何优化此 MySQL 查询 - 在视图内？性能调优

Question

我有一个包含一些 n:m 关系表的数据库，我正在使用一个非常大的查询来组合所有这些表。先来看看我的数据库：

我创建了两个视图来比较性能。

第一个视图：

CREATE VIEW `band_page1` AS (
SELECT maid, band_name, band_logo, band_img, 
    (SELECT countries.country_name from countries WHERE band_info.id_country = countries.id) as country,
    (SELECT locations.location_name from locations WHERE band_info.id_location = locations.id) as location,
    (SELECT status.status_name from status WHERE band_info.id_status = status.id) as status,
    (SELECT founding.fyear from founding WHERE band_info.id_founding = founding.id) as founding,
    (SELECT active.ayear from active WHERE band_info.id_active = active.id) as active,

    (SELECT GROUP_CONCAT(DISTINCT genres.genre_name ORDER BY genres.genre_name) 
     FROM genres LEFT JOIN band_genres ON band_genres.id_genre = genres.id
     WHERE band_genres.id_band = band_info.maid) AS genre,

    (SELECT GROUP_CONCAT(DISTINCT themes.theme_name ORDER BY themes.theme_name) 
     FROM themes LEFT JOIN band_themes ON band_themes.id_theme = themes.id
     WHERE band_themes.id_band = band_info.maid) AS themes,

    (SELECT GROUP_CONCAT(DISTINCT labels.label_name ORDER BY labels.label_name) 
     FROM labels LEFT JOIN band_labels ON band_labels.id_label = labels.id
     WHERE band_labels.id_band = band_info.maid) AS label

FROM band_info
GROUP BY band_info.maid);

第二个视图：

CREATE VIEW `band_page2` AS ( 
         SELECT band_info.maid, band_info.band_name, band_info.band_logo, band_info.band_img, 
        (SELECT countries.country_name from countries WHERE band_info.id_country = countries.id) as country, 
        (SELECT locations.location_name from locations WHERE band_info.id_location = locations.id) as location, 
        (SELECT status.status_name from status WHERE band_info.id_status = status.id) as status, 
        (SELECT founding.fyear from founding WHERE band_info.id_founding = founding.id) as founding, 
        (SELECT active.ayear from active WHERE band_info.id_active = active.id) as active, 
        GROUP_CONCAT(DISTINCT genres.genre_name ORDER BY genres.genre_name) AS genre, 
        GROUP_CONCAT(DISTINCT themes.theme_name ORDER BY themes.theme_name) AS themes, 
        GROUP_CONCAT(DISTINCT labels.label_name ORDER BY labels.label_name) AS label 
        FROM band_info 
    LEFT JOIN band_genres ON band_genres.id_band = band_info.maid
    LEFT JOIN band_themes ON band_themes.id_band = band_info.maid
    LEFT JOIN band_labels ON band_labels.id_band = band_info.maid
    LEFT JOIN genres ON genres.id = band_genres.id_genre 
    LEFT JOIN themes ON themes.id = band_themes.id_theme 
    LEFT JOIN labels ON labels.id = band_labels.id_label
    GROUP BY band_info.maid);

当我转到 phpmyadmin 并打开一个视图时，两个视图都需要 3 秒才能显示查询结果。我正在使用此视图进行如下查询：

SELECT * FROM band_page1 where maid = '$id';

php 感觉好像要花很长时间才能得到结果。这不仅需要 3 秒，还需要更长的时间。我的问题是，如何优化我的查询？

Answer 1

有"over-normalization"这样的东西。

标准 "country codes" 是 2 个字母。让他们 CHAR(2) CHARACTER SET ascii，而不是 INT 到另一个 table。这将该列从 4 个字节减少到 2 个。并摆脱了查找。

YEAR 是一个 2 字节的数据类型；不要费心规范化。

考虑将 status 转换为 1 字节 ENUM 而不是查找。

可能还有其他人。

VIEWs 是语法糖，从不提高性能。有时性能明显更差。

我不认为 GROUP BY 在 first VIEW.

中有任何用处

band_*table好像是多对多映射table。通过遵循 these tips.

可以提高他们的表现

如何优化此 MySQL 查询 - 在视图内？性能调优

How to optimize this MySQL Query - inside a view? Performance tuning

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