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我向查詢添加了OR條件,查詢執行時間從小於0.5秒到達15+秒。在where子句中使用的所有列都被編入索引。想知道如何優化這個查詢。向查詢添加OR條件會降低查詢速度
SELECT SQL_NO_CACHE COUNT(DISTINCT wo.id) AS totrows
FROM wo
LEFT JOIN wu
ON wu.id = wo.id
LEFT JOIN bu
ON bu.id = wu.id
LEFT JOIN ub
ON ub.uid = bu.id
JOIN u
ON u.id = wo.created_by
LEFT JOIN ws
ON ws.wo_id = wo.id, b
WHERE (wo.bid = '13'
AND (wo.created_by IN('2506') OR wo.uid IN('2506'))
AND wo.status != 5
AND (wo.uid = '' || wu.uid in ('406', 0) || wo.uid IS NULL)
AND wo.ut = 0
AND ((wo.wt = 'unit' AND (wo.archive != 1 OR wo.archive IS NULL)) OR wo.wt = 'common')) OR (ws.uid = 2506)
刪除OR (ws.uid = 2506)
使查詢速度非常快。