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bio website blog.jordogskog.no
location Hedmark, Norway
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visits member for 4 years, 1 month
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Nov
17
comment Hardware requirements for one instance Geoserver/PostGIS
Great, then I understand. GeoServer and Java is the bottleneck. But as you say it shouldn't be any problem.
Nov
16
comment Hardware requirements for one instance Geoserver/PostGIS
@user30184 Well, if you cache the output so the server only serves static data I gyess 1 GB will give quite decent performance. And to render and cache 20 mb of data in all zoom levels shouldn't be that heavy, should it? But maybe geoserver is demanding, that I don't know so well.
Oct
28
comment Spatial search performance on a collection of Points in a PostGis database
about "very slow" I have to ask if you really have a functional spatial index. do explain tell you that you have an index scan? and is "very slow" compared to something else or just takes to long to run your query? the slow part of st_dwithin is the recheck where all results from the index scan is checked by real distance calculations. if you just expand bboxes and use the && operator it will be very fast. Look at the sql-definition of st_dwithin how it is done. there is a special trick to keep the index working by expanding one of the two comparing points and then the other.
Oct
28
comment Spatial search performance on a collection of Points in a PostGis database
Well, It can. It could be just that the box have all corners in the point. In PostGIS bboxes is represented with Int32 coordinates and the point with Int64 coordinates. So the box actually has a small area. it doesn't matter if the index gives a few false positive intersections since the result is rechecked.
Oct
14
comment ST spatial queries to select multi-level location
Your query will not work because the query compares all rows to all rows which means that when the point intersect 1 point it also disjoint at least most of the polygons in table 2. So you need to work with a subquery in some way. There are many options.
Sep
28
comment Extract longitude latitude and radius from POSTGIS column
How different value? About radius you can use st_maxdistanse and divide by 2 but it will not give you an exact value either. That is because the buffer is just an appriximation of a circle built of a limited number of points.
Sep
22
comment PostGIS: Get closest point between geometry and Multipoint
No ST_ClosestPoint, ST_ShortestLine and ST_Distance all behave the same. For a collection they iterate all vertexpoints and test against both the vertex points and the line between the points. In some cases it takes a shortcut but the result is the same.
Sep
19
comment PostGIS: Get closest point between geometry and Multipoint
Collecting all geometries from table 2 is a way to compare a geometry in table 1 with all geomeries in table 2. Another way is ordering by distance and using distinct.
Aug
5
comment C# geometry hex decoder
Do you mean that you have no control over the actual query? That seems like making things hard. What you have is wkb as hex values. So you need to read wkb and make that readable for whatever you are going to feed it into.
Jul
18
comment Growth of a PostGIS database for Social Media - Move to Cassandra?
@Jay Cummins, I agree that the question isn't about query design and indexing. But to buy more ram before tuning the query seems like starting in the wrong end. That is more the microsoft/esri way of doing things :-)
Jul
18
comment Growth of a PostGIS database for Social Media - Move to Cassandra?
@mikedotonline ok, but do you have a spatial index that is functional?
Jul
17
comment Growth of a PostGIS database for Social Media - Move to Cassandra?
BTW, you say that you do the selection spatially, but you are also talking about many indexed columns. Why do you have many indexed columns if you don't use them for the selection?
Jul
17
comment Growth of a PostGIS database for Social Media - Move to Cassandra?
Ok, but still. If you have a working spatial index on the geometries I cannot understand that it should take that long time. 350 mill records is not that much.
Jul
17
comment Growth of a PostGIS database for Social Media - Move to Cassandra?
Are you sure it is the selection that is slow and not just the output of all the data. I mean an index search on a integer field like postal codes on 350 mill rows shouldn't be that slow I think.
Jun
16
comment Is it best to use multipolygon or polygon features for large intersect operations?
ST_Split is not the right function here. It will just split the polygon. Use ST_Intersection to get the interesecting part.
Jun
12
comment Closest Point within a Polygon
How is your data stored. If it is in a database like postgis this is a quite simple task with sql.
May
20
comment Function for Selecting Points in a Polygon
@brichins no the postgresql operators will not work on postgis type but as you say PostGIS has it's own that in many cases mean the same. But not alwayas. The last operator in your link also change meaning between PostGIS 1.4 and 1.5 if I recall right to mean only bbox comparasion.
May
18
comment Function for Selecting Points in a Polygon
@brichins, No PostGIS types has nothing to do with the PosgreSQL types. I don't even think there is some simåle cast between them. You have to use the PostGIS types to use the PostGIS functions.
May
15
comment PostGis geometry name lookup failed for table
A column of type polygon that contains points? I do not understand from what you are trying to build geometries. But to build a PostGIS geometry you will need to use a geometry constructor function like ST_Point(x, y).
May
15
comment How do I get started with PostGis
The url of today is postgis.net/documentation instead