[postgis-users] Spatial Query - Why I cannot select geom as I want?

[Ethan Alpert]

Why is the spatial reference -1 for your GeomFromText() constructor?
What is the SRID for the table you are querying? Are you sure they
contain the same units?
 
-e

	-----Original Message-----
	From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of
Willa WEI
	Sent: Monday, November 21, 2005 10:29 AM
	To: postgis-users at postgis.refractions.net
	Subject: [postgis-users] Spatial Query - Why I cannot select
geom as I want?
	
	
	Dear PostGISs,
	 
	I downloaded Postgres 8.1 and loaded some polygon shape files
using shp2postgres tool. Then I followed the instruction to build GIST
index for the geom columns. However, when I tried to use spatial query
via JDBC to select polygons, I couldn't select any polygon with spatial
query. Here are the ways I did:
	 
	First, I use the sample code in the user manual to select
polygons from the geo table and print the geometries. then, I pick up
one point from the screen to use it as the geospatial reference for the
queries.
	 
	
	Query 1, I used the reference point as the center point to make
it as polygon. then submitted the query as follow:
	WHERE the_geom && GeomFromText('POLYGON((-117.05338168844499
33.0161157574187, -117.05338168844499 33.0191157574187,
-117.050381688445 33.0191157574187, -117.050381688445 33.0161157574187,
-117.05338168844499 33.0161157574187))',-1)

	The query result set returned  0 row.
	 
	Query 2, I used the reference point to make a bounding box and
submitted the spatial query as BOX3D.
	The result set still contained 0 row.

	Query 3, I used reference point and composed a query as
distance from the point. Still, I got 0 row when queried a small table
and Jave out of memory error when queried a large table (900,000 rows).

	Is there anybody who knows what is the problem?  I used postgres
query tool to create the GIST index and Maintenance tool to VACUUM and
Analyze the table (the comand VACUUM on the column didn't work). I
checked the index in the database, it is there. What else could be go
wrong in my procedures?

	 

	Thanks in advance for your help,

	Willa

	

	 

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