17
votes
Accepted
Prevent export to shapefile from PostGIS table in QGIS
Once you allow a user to select the data from your database there is no way to prevent them doing what they like with the data. If it is important to you that the user can only view and not edit the ...
- 82.6k
13
votes
Poor performance with storing large rasters in PostGIS and visualising in QGIS
If you want to display large rasters in QGIS, you have to build pyramids, either for a tif image on the file system or for a image registered in Postgis.
The performance difference in QGIS rendering ...
- 5,465
13
votes
How to open QGIS project without being asked for PostGIS credentials every time
A very good solution is to use a connection service file.
Using this, you can have your credentials in one file, completely independent of QGIS.
You can share the project. Other users can use the same ...
- 5,465
11
votes
Reading/writing local datastore for QGIS?
How about a local PostGIS instance? PostgeSQL can be downloaded from https://www.postgresql.org/download/ to which a PostGIS extension can be created to make it a spatial database. Also recommended ...
- 3,632
9
votes
Adding PostgreSQL database to web map
You can't talk directly from a web browser to a database, because a browser runs code on a client's computer, and that doesn't (and shouldn't) connect directly to your database.
What you need is a ...
- 13.5k
8
votes
Prevent export to shapefile from PostGIS table in QGIS
Some time ago I had the same challenge. What I did was remove the button export to the interface qgis to users who didn't have a permission.
How to? I leave some tips...
QGis interface uses the ...
- 176
7
votes
Accepted
Adding Timestamp to attribute table in QGIS
Using the QGIS field calculator you can create an expression on a Time type field, with the speed as a variable. Changing the speed and re-calculating the expression will adjust the times accordingly. ...
- 17.7k
6
votes
Poor performance with storing large rasters in PostGIS and visualising in QGIS
Not sure if it was your case, but I found out -I should not be used together with appending data -a.
I was importing many TIF files into a DB, and -I actually creates the index again and performs ...
- 181
5
votes
Accepted
Normalizing a spatial datasource (5NF)?
You probably won't use your data in normal form, your tools will expect relatively flat, denormalized inputs.
You probably won't update your data in normal form, you'll receive flat, denormalized bulk ...
- 19.9k
5
votes
Storing different shapefiles as "one" in QGIS?
By definition, a shapefile can store one specific type of geometry. So it would not be possible to store layers of different geometry in one shapefile.
One way to share the data would be to share the ...
- 1,986
5
votes
Accepted
Appending characters before the filename of all layers in a GeoPackage in QGIS?
You must rename layers one by with SQL ALTER TABLE... See https://gdal.org/drivers/vector/gpkg.html. For renaming many layers automatically you should make a script that first gets the list of the ...
- 67.9k
4
votes
Accepted
PostGIS - query maximum distance between two polygons
There is no such function, but you can create the functionality yourself (although it can be slow for large datasets) by calculating the distance from every point in the red polygon to the blue ...
- 3,279
4
votes
Why does rendering from a view take significantly longer than rendering from a table?
I believe that the underlying query (used to make the view) will be executed every time you try to access the view, where if you are just using the source table the select will much simpler.
This ...
- 91
4
votes
Accepted
subtract polygons from other polygons with SQL
If you are working with SQL Server 2012+ then you should be able to do this within a single query. Don't expect it to be very performent, but do make sure that you have all the appropriate indexes (...
- 3,430
4
votes
How to transfer table from localhost server to another server in PostgreSQL
In a terminal you can use a command line like :
pg_dump -t "schema1"."table1" -h host1_ip -U username1 dbname1 | psql -h host2_ip -U username2 dbname2;
This would transfer table1 (in schema1) from ...
- 115
4
votes
Accepted
Difference between SpatialJoin with "...where..." and "join...on..."
No one difference for both statement. Postgresql converts both it to the same query plan. You can see plans by just add EXPLAIN ANALYZE before your select and looks for result.
- 156
4
votes
Accepted
Storing different shapefiles as "one" in QGIS?
You can revert back to Spatialite databases. Use the extension "QSpatialite" to create an empty DB (use the creation button, circled on the capture below), and add your layers to it.
To add a layer, ...
- 96
4
votes
Accepted
Visualize geographic spatial data from SQL Server directly in PowerBI
So my research at this point points to NO... which is startling. I even watched an entire ESRI UC presentation on the subject from last summer (link), and even investigating the Mapbox components, ...
- 18.9k
4
votes
GIS Database format functional differences
It sounds like you have two paths, but need to distinguish each option.
Files on a shared drive - SQLite/Spatialite is a file-based database that may serve the purpose. GeoPackage are flat files much ...
- 18.9k
4
votes
I just imported some shapefiles to a PostGIS database, where can I find the files in my drive?
PostgreSQL uses an internal, efficient storage for the data. There are no human-readable or human-identifiable files in your filesystem. Your imported geo data is now accessible via SQL only.
- 11.1k
3
votes
Requirement to use a spatial database - Why use a spatial database?
A spatial database doesn't hold shapefiles per se. However, it does store geometry associated with a feature/row. In your case, the boreholes would be stored as points with an x,y,z coordinate. It'...
- 21.9k
3
votes
How to transfer table from localhost server to another server in PostgreSQL
There are two ways that are depending on PostgreSQL version and connectity.
Use the backup (for all versions, and integrated in most admin tools):
With pgdump you can export your table, send the ...
- 6,255
3
votes
Why does rendering from a view take significantly longer than rendering from a table?
I've noticed the same thing on spatial views that return a large amount of data in PostgreSql and it is caused by QGIS issuing a SELECT count(distinct (id))=count((id)) FROM schema.view to verify the ...
- 14.7k
3
votes
Calculate centroid of a point cluster
I am not sure I really understand what you are doing.
How can a point cluster be a collection of linestrings?
, but ..
Remember you are using a spatial database, why not use the functionality in ...
- 13.3k
3
votes
Convex hull with n points using computational geometry libraries
ST_ConvexHull
It is often used to determine an affected area based on a set of point observations.
Also worth nothing,
It is usually used with MULTI and Geometry Collections. Although it is ...
- 7,111
3
votes
Accepted
State of GeoServer SQL Server Extension
It has extension (rather than community module) status, so there is at least some support. However there are better database options (those in core distribution are likely better supported than ...
- 12.9k
3
votes
Accepted
Where to put vector layers with different CRS in a PostGIS database?
There are no hard and fast rules for how to handle datasets with different projections, but here are some general comments on the separate database/schema question.
Separate databases
Separate ...
- 13.7k
3
votes
How to find parent-child relationships between geometric features? Or is there another way of dealing with GIS data?
The relationships that you mentioned are called topological relationships (relationships that do not depend on the shape of the features) in GIS. The majority of the situations can be represented ...
- 49.8k
3
votes
Accepted
Joining tables based on distance using SQL Server
4326 SRID
Microsoft SQL doesn't use SRID, so 4326 or 9999 isn't a problem. Like MySQL they just error on SRID mismtach. They do have a geographic object. They also don't follow any spec whatsoever ...
- 7,111
Only top scored, non community-wiki answers of a minimum length are eligible