查詢背景

有一個表tmp_test_course大概有10萬條記錄，然后有個json字段叫outline，存了一對多關系(保存了多個編碼，例如jy1577683381775)

我們需要在這10萬條數據中檢索特定類型的數據，目標總數據量：2931條

SELECT COUNT(*) FROM tmp_test_course WHERE `type`=5 AND del=2 AND is_leaf=1

我們在限定為上面類型的同時，還得包含下面任意一個編碼（也就是OR查詢）

jy1577683381775
jy1577683380808
jy1577683379178
jy1577683378676
jy1577683377617
jy1577683376672
jy1577683375903
jy1578385720787
jy1499916986208
jy1499917112460
jy1499917093400
jy1499917335579
jy1499917334770
jy1499917333339
jy1499917331557
jy1499917330833
jy1499917329615
jy1499917328496
jy1576922006950
jy1499916993558
jy1499916992308
jy1499917003454
jy1499917002952

下面分別列出4種方式查詢outline字段，給出相應的查詢時間和掃描行數

一、like查詢

耗時248毫秒

SELECT * FROM tmp_test_course 
WHERE `type`=5 AND del=2 AND is_leaf=1 
AND (
outline like '%jy1577683381775%'
OR outline like '%jy1577683380808%'
OR outline like '%jy1577683379178%'
OR outline like '%jy1577683378676%'
OR outline like '%jy1577683377617%'
OR outline like '%jy1577683376672%'
OR outline like '%jy1577683375903%'
OR outline like '%jy1578385720787%'
OR outline like '%jy1499916986208%'
OR outline like '%jy1499917112460%'
OR outline like '%jy1499917093400%'
OR outline like '%jy1499917335579%'
OR outline like '%jy1499917334770%'
OR outline like '%jy1499917333339%'
OR outline like '%jy1499917331557%'
OR outline like '%jy1499917330833%'
OR outline like '%jy1499917329615%'
OR outline like '%jy1499917328496%'
OR outline like '%jy1576922006950%'
OR outline like '%jy1499916993558%'
OR outline like '%jy1499916992308%'
OR outline like '%jy1499917003454%'
OR outline like '%jy1499917002952%'
)

EXPLAIN分析結果如下，全表掃描

二、json函數查詢

使用函數JSON_SEARCH，更多函數請查看MySQL官方文檔

可以看到，查詢耗時196毫秒，速度稍微快了一點

SELECT * FROM tmp_test_course 
WHERE `type`=5 AND del=2 AND is_leaf=1
AND 
(
JSON_SEARCH(outline, 'one', 'jy1577683381775') IS NOT NULL OR
JSON_SEARCH(outline, 'one', 'jy1577683380808') IS NOT NULL OR
JSON_SEARCH(outline, 'one', 'jy1577683379178') IS NOT NULL OR
JSON_SEARCH(outline, 'one', 'jy1577683378676') IS NOT NULL OR
JSON_SEARCH(outline, 'one', 'jy1577683377617') IS NOT NULL OR
JSON_SEARCH(outline, 'one', 'jy1577683376672') IS NOT NULL OR
JSON_SEARCH(outline, 'one', 'jy1577683375903') IS NOT NULL OR
JSON_SEARCH(outline, 'one', 'jy1578385720787') IS NOT NULL OR
JSON_SEARCH(outline, 'one', 'jy1499916986208') IS NOT NULL OR
JSON_SEARCH(outline, 'one', 'jy1499917112460') IS NOT NULL OR
JSON_SEARCH(outline, 'one', 'jy1499917093400') IS NOT NULL OR
JSON_SEARCH(outline, 'one', 'jy1499917335579') IS NOT NULL OR
JSON_SEARCH(outline, 'one', 'jy1499917334770') IS NOT NULL OR
JSON_SEARCH(outline, 'one', 'jy1499917333339') IS NOT NULL OR
JSON_SEARCH(outline, 'one', 'jy1499917331557') IS NOT NULL OR
JSON_SEARCH(outline, 'one', 'jy1499917330833') IS NOT NULL OR
JSON_SEARCH(outline, 'one', 'jy1499917329615') IS NOT NULL OR
JSON_SEARCH(outline, 'one', 'jy1499917328496') IS NOT NULL OR
JSON_SEARCH(outline, 'one', 'jy1576922006950') IS NOT NULL OR
JSON_SEARCH(outline, 'one', 'jy1499916993558') IS NOT NULL OR
JSON_SEARCH(outline, 'one', 'jy1499916992308') IS NOT NULL OR
JSON_SEARCH(outline, 'one', 'jy1499917003454') IS NOT NULL OR
JSON_SEARCH(outline, 'one', 'jy1499917002952') IS NOT NULL   
)

EXPLAIN分析結果如下，還是全表掃描

三、聯合索引查詢

下面為該表建立一個聯合索引(本來想建一個type-del-is_leaf-outline的索引，但是outline字段太長限制，所以只加type-del-is_leaf的聯合索引

ALTER TABLE tmp_test_course ADD KEY `type-del-is_leaf` (`type`,`del`,`is_leaf`)

加入索引后再執行like和json查詢，明顯提速。like執行用了136毫秒，json查詢用了82.6毫秒，由此可見針對json類型使用json函數查詢比like快

EXPLAIN分析結果如下，兩者查詢掃描的行數都限定在了2931行

四、全文索引查詢

因為全文索引只支持CHAR、VARCHAR和TEXT，我們需要把JSON字段定義改一下

ALTER TABLE tmp_test_course MODIFY `outline` VARCHAR(1024) NOT NULL DEFAULT '[]'

添加全文索引

ALTER TABLE tmp_test_course ADD FULLTEXT INDEX outline (outline);

現在再來用全文索引進行檢索

SELECT * FROM tmp_test_course 
WHERE `type`=5 AND del=2 AND is_leaf=1
AND 
MATCH(outline) AGAINST ('jy1577683381775 jy1577683380808 jy1577683379178 jy1577683378676 jy1577683377617 jy1577683376672 jy1577683375903 jy1578385720787 jy1499916986208 jy1499917112460 jy1499917093400 jy1499917335579 jy1499917334770 jy1499917333339 jy1499917331557 jy1499917330833 jy1499917329615 jy1499917328496 jy1576922006950 jy1499916993558 jy1499916992308 jy1499917003454 jy1499917002952')

耗時11.6毫秒,速度提升極其明顯，可見全文索引的牛逼。