![]() RAISE EXCEPTION 'The new geometry must be completely within the boundaries of the limits layer' Ī more advanced example on validation and keeping history of changes: Vf := (SELECT ST_Within(NEW.geom, geom) FROM boundaries WHERE ST_Within(NEW.geom, geom)) Check the geometry is completely contained within the boundaries of a polygon layer RAISE EXCEPTION 'Description cannot be empty' Check the description of the observation ![]() VALUES (OLD.col1, OLD.col2, OLD.col3, session_user, current_timestamp, OLD.geom) įunction to add some attribute/geometry validation (see more here: ) CREATE OR REPLACE FUNCTION update_observation() INSERT INTO backup_table (col1, col2, editor, col3, username, edit_data, geom) WHEN (OLD.edited_column IS DISTINCT FROM NEW.edited_column)Ī very simple but effective way of keeping history of changes in a table (backup table structure identical to the one being backed up, plus some other columns to save some additional info): CREATE OR REPLACE FUNCTION backup_row() NEW.column_to_be_filled_with_username = session_user ĭROP TRIGGER IF EXISTS data_adduser ON schema.tablename ĬREATE TRIGGER data_adduser BEFORE UPDATE ON schema.tablename You can exclude the schema which you don't want to drop by adding another condition hereĮXECUTE 'GRANT ALL ON SCHEMA ' || rec.schemaname || ' TO username' Īdd a sequence to an (editable) view: ALTER VIEW schema.tablename ALTER gid SET DEFAULT nextval('schema.tablename_gid_seq') Function/trigger to get/save the (database) username when doing an INSERT or UPDATE Loop schema names and run a whatever query: CREATE OR REPLACE FUNCTION change_all() List tables owned by a specific user: SELECT *Ĭhange permissions on all tables in the same schema: REVOKE ALL ON ALL TABLES IN SCHEMA schemaname FROM username List database triggers: SELECT * FROM information_iggers Points_clusters b WHERE ST_Within(a.geom,b.geom)) SELECT a.gid AS id_point,b.gid AS id_buffer,a.geom AS geom, row_number() OVER (PARTITION BY b.gid ORDER BY a.gid) AS rownum FROM points a, SELECT DISTINCT ON (geom) id_point, geom FROM ( Then CREATE TABLE points_without_closest AS SELECT row_number() over() AS gid, geom AS geom FROM temp_table WITH temp_table AS (SELECT (ST_Dump(ST_Union(ST_Buffer(geom, 0.2, 'quad_segs=100')))).geom::geometry(POLYGON,3047) AS geom FROM points) If is needed to know how many points are in each cluster/Geometr圜ollection the ST_NumGeometries can be used: SELECT unnest(ST_ClusterWithin(f.geom, 0.4)) AS geom, ST_NumGeometries(unnest(ST_ClusterWithin(f.geom, 0.4))) AS ngĪ different approach, not as fast as the above, could be: CREATE TABLE points_clusters AS In the example above the distance used for this analysis is 0.4 meters, and with ST_GeometryN we extract always the 1st geometry from the cluster/Geometr圜ollection of points, because for this problem a) is not important what point we keep (in the cluster) and b) the first geometry of a Geometr圜ollection always exist. ST_GeometryN extracts the Nth geometry from a Geometr圜ollection.unnest splits the array and puts each element into a separate row. ![]() All the Geometr圜ollection are placed into an array ST_ClusterWithin creates a cluster/Geometr圜ollection where each Geometr圜ollection represents a set of geometries separated by no more than the specified distance.It turns out that the right (and spectacularly fast) solution is: SELECT ST_GeometryN(unnest(ST_ClusterWithin(f.geom, 0.4)),1) AS geom FROM points AS f To solve this problem a number of possible solutions may come to mind, usually this are not very straightforward and/or very slow. ![]()
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