如何优化SQLite索引？

Question

我有一个表t1和两个索引:

create index if not exists timeindex on t1(time, "Bytes Received")
create index if not exists filenameindex on t1(filename)

下一个查询执行得足够快:

select "Bytes Received" from t1 where time>="11:19:31.18" and time <= "11:19:36.18"

但是当我向WHERE语句添加一个附加条件时,查询会大大减慢

select "Bytes Received" 
    from t1 
    where time>="11:19:31.18" and time <= "11:19:36.18"
    and filename = "SE12.log"

我试图创建一个新索引,t1(time, "Bytes Received", filename)但执行速度没有改变.

我应该如何更改表中的索引以加快查询速度？

Answer 1

使用BETWEEN和以下索引:

CREATE INDEX IF NOT EXISTS fntimeindex ON t1(filename ASC, time ASC);
SELECT "Bytes Received"
  FROM t1 INDEXED BY fntimeindex
  WHERE filename = 'SE12.log'
   AND time BETWEEN '11:19:31.18' AND '11:19:36.18';

另请注意,SQL字符串用简单的引号括起来(双引号用于表,模式和列名).