Question

我有一个包含两个表，区域和属性的数据库，每个包含100万行。现在我们发现在给定区域内有多少属性，我们正在使用此查询，但需要时间来获取

SELECT count(*) FROM properties 
WHERE ST_Intersects(geom, '01030000000100000005000000456458C51B375240C173EFE1922333400E10CCD1E3375240335019FF3E23334011AAD4EC81385240E4BD6A65C227334068B3EA73B5375240FA449E245D2B3340456458C51B375240C173EFE192233340')

我们可以采用更好的方法吗？

执行计划

"Aggregate  (cost=38932.37..38932.38 rows=1 width=0)"
"  ->  Bitmap Heap Scan on properties  (cost=463.41..38921.03 rows=4533 width=0)"
"        Recheck Cond: (geom && '01030000000100000005000000456458C51B375240C173EFE1922333400E10CCD1E3375240335019FF3E23334011AAD4EC81385240E4BD6A65C227334068B3EA73B5375240FA449E245D2B3340456458C51B375240C173EFE192233340'::geometry)"
"        Filter: _st_intersects(geom, '01030000000100000005000000456458C51B375240C173EFE1922333400E10CCD1E3375240335019FF3E23334011AAD4EC81385240E4BD6A65C227334068B3EA73B5375240FA449E245D2B3340456458C51B375240C173EFE192233340'::geometry)"
"              Index Cond: (geom && '01030000000100000005000000456458C51B375240C173EFE1922333400E10CCD1E3375240335019FF3E23334011AAD4EC81385240E4BD6A65C227334068B3EA73B5375240FA449E245D2B3340456458C51B375240C173EFE192233340'::geometry)"

Answer 1

教科书的答案是，您应首先检查每个几何体上边界框的重叠。我当然发现两个表中有大量几何图形的查询：

select xxx  from   A, B
   where   A.geom && B.geom
                 AND
           ST_INTERSECTS(a.geom,b.geom);

...比单独使用ST_INTERSECTS更快地运行四个数量级。

ST_Intersects花时间获取结果

1 个答案: