MySQL查询性能极限？

Question

我们有一个自行开发的文档管理系统，但我们的系统运行速度非常慢，尤其是在搜索方面。一开始它运行良好，但随着时间的推移它变得越来越慢。根据标准，现在需要 30 到 150 秒才能返回结果。这是我们的搜索查询。我们一直在左右盯着这个东西，看不到任何可以调整它的地方。所有连接的字段都在各自的表中建立了索引。

SELECT DISTINCT f.*, ts.*, fo.*, ft.*, p.*, u.*, c.*, co.*, ct.*, fs.*, fd.*, r.*, rt.*, si.*, s.* FROM (
SELECT DISTINCT f.* FROM files f
JOIN folders fo ON(fo.id = f.belongs_to_folder_id)
JOIN projects p ON(p.id = f.belongs_to_project_id)
LEFT OUTER JOIN file_statuses fs ON(fs.id = f.file_status_id)
LEFT OUTER JOIN submittal_items_files sif ON(sif.file_id = f.id)
LEFT OUTER JOIN submittal_items si ON(si.id = sif.submittal_item_id)
LEFT OUTER JOIN submittals s ON(s.id = si.belongs_to_submittal_id)
LEFT OUTER JOIN record_types rt ON(rt.id = f.record_type_id)
LEFT OUTER JOIN companies co ON(co.id = f.company_id)
LEFT JOIN folders_actions_groups ag ON (
    f.belongs_to_folder_id = ag.folder_id AND
    ag.action_id = 10010
)
LEFT JOIN files_actions_groups fg ON (fg.file_id = f.id)
JOIN users_groups ug ON ((ug.group_id = ag.group_id OR ug.group_id = fg.group_id) AND ug.user_id = 411)
WHERE (
    (f.file_generated_name LIKE CONCAT('%', 'the', '%')) OR 
    (f.record_id LIKE CONCAT('%', 'the', '%')) OR 
    (f.record_title LIKE CONCAT('%', 'the', '%')) OR 
    (f.additional_info LIKE CONCAT('%', 'the', '%')) OR 
    (si.item_number LIKE CONCAT('%', 'the', '%')) OR 
    (s.element_number LIKE CONCAT('%', 'the', '%'))
) AND f.path LIKE CONCAT('Some Text', '%') AND 
f.file_status_id = 3 AND 
f.file_revision = 1 AND 
f.discipline_id = 1 AND 
f.record_type_id = 2 AND 
f.triage_status_id = 2 AND 
f.deleted = 0 
ORDER BY f.created DESC, f.id DESC  
LIMIT 100
) AS f
LEFT OUTER JOIN users u ON(f.created_by_user_id = u.id)
LEFT OUTER JOIN contacts c ON(c.user_id = u.id)
LEFT OUTER JOIN companies co ON(co.id = f.company_id)
LEFT OUTER JOIN company_types ct ON(ct.id = co.company_type_id)
JOIN triage_statuses ts ON(f.triage_status_id = ts.id)
JOIN folders fo ON(fo.id = f.belongs_to_folder_id)
JOIN folder_types ft ON(ft.id = fo.folder_type_id)
JOIN projects p ON(p.id = f.belongs_to_project_id)
LEFT OUTER JOIN file_statuses fs ON(fs.id = f.file_status_id)
LEFT OUTER JOIN file_disciplines fd ON(fd.id = f.discipline_id)
LEFT OUTER JOIN revisions r ON(r.id = f.file_revision)
LEFT OUTER JOIN record_types rt ON(rt.id = f.record_type_id)
LEFT OUTER JOIN submittal_items_files sif ON(sif.file_id = f.id)
LEFT OUTER JOIN submittal_items si ON(si.id = sif.submittal_item_id)
LEFT OUTER JOIN submittals s ON(s.id = si.belongs_to_submittal_id)
LEFT OUTER JOIN files_actions_groups ffg ON(ffg.file_id = f.id)
LEFT OUTER JOIN groups g ON(g.id = ffg.group_id)
ORDER BY f.created DESC, f.id DESC

Answer 1

这可能是一个显而易见的答案，但您是否已为数据库编制索引？如果您不熟悉索引，这里有一个很好的规则:只需在所有名为“id”的列上放置一个唯一索引，例如 folders.id 或 projects.id，然后在所有引用一个索引的列上放置一个标准索引外部 ID，例如 folder.belongs_to_folder_id 或 folder.record_type_id

我要更改的另一件事是尝试只选择您实际使用的列，而不是您的庞大列表 f.*, ts.*, fo.*, ft.*, p.*, u .*、c.*、co.*、ct.*、fs.* 等...

您还有大量的连接，这在处理时间方面非常昂贵。您真的需要所有这些连接表吗？