在集群数据库上运行PostGIS命令

Question

Using Postgresql in clustered database (stado) on two nodes, I want to test this query:

select id,position,timestamp from table t1 WHERE id!=0 AND ST_Intersects ((Select ST_Buffer_Meters(ST_SetSRID(ST_MakePoint(61.4019,15.218205), 4326) ,1160006)),position) AND timestamp Between '2013-10-01' and '2013-12-30';

When I run it in command line or psql (on coordinator), I get this error:

Encountered ")" at line 1, column 171.

While other sql commands (insert, update, select... etc) are working fine. also Geometry columns seems okay in the table so i don't think there is a problem with installing PostGIS.

Answer 1

Generally-speaking, don't buffer a geometry to do a proximity search. With the above attempt, it is for just one point geometry, but in other queries you could be potentially buffering all the geometries of a table, which would make the query expensive since it would need to create new geometries and would not be able to use indexes. Use ST_DWithin instead .

ST_DWithin with geometry types will use the same distance units as the the spatial reference system. So for SRID=4326, this is in degrees, which is not helpful in any way. However, if position is a geography type, ST_DWithin will use distance arguments in meters, which is much more useful. So the WHERE filter would look like:

WHERE id <> 0
  AND ST_DWithin(ST_MakePoint(61.4019, 15.218205)::geography, position, 1160006)
...

This will do a proximity search of positions that are 1160006 m or 1160 km from the queried location (which, by the way is not in Sweden, if that's where you were thinking). If position is a geometry type, you can either consider changing the type, or do a cast ( position::geography ) or an index of that cast operation.

Answer 2

I can't find the function ST_Buffer_Meters() in the PostGis manual, only ST_Buffer()

Either way, I can't imagine any function would require a subquery as parameter. Try instead:

SELECT id,position,timestamp
FROM   table t1
WHERE  id <> 0
AND    ST_Intersects(ST_Buffer_Meters(ST_SetSRID(
                     ST_MakePoint(61.4019, 15.218205), 4326), 1160006), position)
AND    timestamp BETWEEN '2013-10-01' AND '2013-12-30';

And don't use timestamp as identifier. It's a base type name and a reserved word in SQL .