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以下查询需要3.06分钟才能执行。如何加快此查询?如何在执行查询时使用现有的索引列?使用ST_Intersects查询性能问题()
SELECT samples_collected.talukname,sample_count,TotalSamples from
(
SELECT a.talukname talukname, COUNT (DISTINCT b.globalid) sample_count
FROM village a, gridpoint_1 b ,gridpoint_1__attach c
WHERE st_intersects(a.shape,b.shape)
and b.globalid=c.rel_globalid
and a.districtname='Bagalkot'
GROUP BY a.talukname
) samples_collected,
(
SELECT a.talukname talukname,COUNT (DISTINCT b.globalid) TotalSamples
FROM village a
INNER JOIN
gridpoint_1 b ON st_intersects(a.shape,b.shape)
WHERE a.districtname='Bagalkot'
GROUP BY a.talukname
) total
WHERE samples_collected.talukname=total.talukname;
运行'explain analyze(your_select_query)'并使用http://explain.depesz.com/分析结果 –