SQL 查询速度太慢（flutter mobile）

Question

我不确定以下查询有什么问题。

对于 size/length 中提供的更大的 names 数组，查询似乎运行非常慢（可能呈指数级缓慢，不确定）：

以下是 mytable 的列：

name, timestamp, diff, diff2, ratio, minus_one

minus_one 列只是一个辅助列，对于每个插入的行，它始终具有 -1 的值。

有人可以帮助优化查询吗？或者你认为这很好吗？也许应该优化我代码的其他部分以运行它更快？非常感谢任何建议。

查询：

SELECT 
    COUNT(diff) AS count, 
    IFNULL(AVG(diff), 0) AS avg, 
    IFNULL(MAX(diff), 0) AS max, 
    IFNULL(MIN(diff), 0) AS min 
FROM 
    mytable 
WHERE 
    name IN :names 
    AND timestamp >= :start 
    AND timestamp <= :end 
    AND ratio <> -1 
    AND (minus_one = :ratioStart OR ratio >= :ratioStart) 
    AND (minus_one = :ratioEnd OR ratio <= :ratioEnd) 
    AND (minus_one = :diffStart OR diff >= :diffStart)
    AND (minus_one = :diffEnd OR diff <= :diffEnd) 
    AND (minus_one = :diffStart2 OR diff2 >= :diffStart2) 
    AND (minus_one = :diffEnd2 OR diff2 <= :diffEnd2) 
GROUP BY 
    name 
ORDER BY 
    count DESC

Answer 1

那是因为where子句的查询时间比较长。您可以通过执行以下操作之一改进查询：

使用多列索引：

CREATE INDEX index_name ON table(col1, col2);

使用 sqflite 插件

SQL 查询速度太慢（flutter mobile）

SQL query is too slow (flutter mobile)

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