语句1SELECT
ID
FROM
TABLE111
WHERE COL1 = 33
AND COL2 != 26
AND COL3 = 0
AND COL4 = 1
语句2SELECT
ID
FROM
TABLE111
WHERE COL1 != 33
AND COL2 = 26
AND COL3 = 0
AND COL4 = 1 我有个覆盖索引
COL1 ,COL2 ,COL3 ,COL4,ID两条语句都能用到覆盖索引,
单数差距在下面,第一条只扫描了所需要的行
第二条扫描了所有
1 PRIMARY SE_BASE_CONFIG range cover_index cover_index 4 (NULL) 100 Using where; Using index2 UNION SE_BASE_CONFIG range cover_index cover_index 2 (NULL) 52526 Using where; Using indexsql索引覆盖索引
ID
FROM
TABLE111
WHERE COL1 = 33
AND COL2 != 26
AND COL3 = 0
AND COL4 = 1
语句2SELECT
ID
FROM
TABLE111
WHERE COL1 != 33
AND COL2 = 26
AND COL3 = 0
AND COL4 = 1 我有个覆盖索引
COL1 ,COL2 ,COL3 ,COL4,ID两条语句都能用到覆盖索引,
单数差距在下面,第一条只扫描了所需要的行
第二条扫描了所有
1 PRIMARY SE_BASE_CONFIG range cover_index cover_index 4 (NULL) 100 Using where; Using index2 UNION SE_BASE_CONFIG range cover_index cover_index 2 (NULL) 52526 Using where; Using indexsql索引覆盖索引
解决方案 »
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