我相信这是因为MySQL不支持合并空间索引.不知道如果它仍然是真的,但我已经读过它在过去的某个地方.如果您有OR语句,则不使用空间索引

在你的情况下,你在做什么point.id = 1,这是一个直接选择,一个返回的结果被用于mbrcontains.这使用索引.

当你添加point.in(1,2,3),它返回3个结果,每个需要映射到范围表,因此不起作用

结果

id select_type table type possible_keys key key_len ref rows filtered Extra

1 SIMPLE points range PRIMARY PRIMARY 4 NULL 3 100.00 Using where

1 SIMPLE ranges ALL poly NULL NULL NULL 6467418 100.00

您可以通过执行以下操作来简化测试：SELECT * FROM范围,其中mbrcontains(poly,GEOMFROMWKB(POINT(0,0)))

id select_type table type possible_keys key key_len ref rows filtered Extra

1 SIMPLE ranges range poly poly 34 NULL 1 100.00 Using where

现在这个SELECT * FROM范围,其中mbrcontains(poly,GEOMFROMWKB(POINT(0,0)))或mbrcontains(poly,GEOMFROMWKB(POINT(10,10)))

结果

id select_type table type possible_keys key key_len ref rows filtered Extra

1 SIMPLE ranges ALL poly NULL NULL NULL 6467418 100.00 Using where

看到在第二种情况下,你不使用索引,只是扫描.

您可以通过为每个特定点创建UNION来强制查询使用索引,但我不知道这是否会更快.我在本地做了一些测试,它比你的第一个查询慢一点.

EXPLAIN EXTENDED

SELECT *

FROM points

FORCE INDEX (PRIMARY )

LEFT JOIN ranges

FORCE INDEX ( poly ) ON mbrcontains( poly, point )

WHERE points.id = 1

UNION DISTINCT

SELECT *

FROM points

FORCE INDEX (PRIMARY )

LEFT JOIN ranges

FORCE INDEX ( poly ) ON mbrcontains( poly, point )

WHERE points.id = 2

UNION DISTINCT

SELECT *

FROM points

FORCE INDEX (PRIMARY )

LEFT JOIN ranges

FORCE INDEX ( poly ) ON mbrcontains( poly, point )

WHERE points.id = 3

结果

id select_type table type possible_keys key key_len ref rows filtered Extra

1 PRIMARY points const PRIMARY PRIMARY 4 const 1 100.00

1 PRIMARY ranges range poly poly 34 NULL 1 100.00 Using where

2 UNION points const PRIMARY PRIMARY 4 const 1 100.00

2 UNION ranges range poly poly 34 NULL 1 100.00 Using where

3 UNION points const PRIMARY PRIMARY 4 const 1 100.00

3 UNION ranges range poly poly 34 NULL 1 100.00 Using where

NULL UNION RESULT ALL NULL NULL NULL NULL NULL NULL