10

i have a postgres database with millions of rows in it it has a column called geom which contains the boundary of a property.

using a python script i am extracting the information from this table and re-inserting it into a new table.

when i insert in the new table the script bugs out with the following:

Traceback (most recent call last):
  File "build_parcels.py", line 258, in <module>
    main()
  File "build_parcels.py", line 166, in main
    update_cursor.executemany("insert into parcels (par_id, street_add, title_no, proprietors, au_name, ua_name, geom) VALUES (%s, %s, %s, %s, %s, %s, %s)", inserts)
psycopg2.IntegrityError: new row for relation "parcels" violates check constraint "enforce_geotype_geom"

The new table has a check constraint enforce_geotype_geom = ((geometrytype(geom) = 'POLYGON'::text) OR (geom IS NULL)) whereas the old table does not, so im guessing theres dud data or non polygon (perhaps multipolygon data?) in the old table. i want to keep the new data as polygon so want to not insert anything else.

Initially i tried wrapping the query with standard python error handling with the hope that the dud geom rows would fail but the script would keep running , but the script has been written to commit at the end not each row so it doesnt work.

I think what i need to do is iterate through the old table geom rows and check what type of geometry they are so i can establish whether or not i want to keep it or throw it away before i insert into the new table

Whats the best way of going about this?

4

3 に答える 3

8

PostGIS SQL のこの驚くほど便利なビットは、それを理解するのに役立つはずです...ここには多くのジオメトリ タイプのテストがあります。

-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-- 
-- $Id: cleanGeometry.sql 2008-04-24 10:30Z Dr. Horst Duester $
--
-- cleanGeometry - remove self- and ring-selfintersections from 
--                 input Polygon geometries 
-- http://www.sogis.ch
-- Copyright 2008 SO!GIS Koordination, Kanton Solothurn, Switzerland
-- Version 1.0
-- contact: horst dot duester at bd dot so dot ch
--
-- This is free software; you can redistribute and/or modify it under
-- the terms of the GNU General Public Licence. See the COPYING file.
-- This software is without any warrenty and you use it at your own risk
--  
-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -


CREATE OR REPLACE FUNCTION cleanGeometry(geometry)
  RETURNS geometry AS
$BODY$DECLARE
  inGeom ALIAS for $1;
  outGeom geometry;
  tmpLinestring geometry;

Begin

  outGeom := NULL;

-- Clean Process for Polygon 
  IF (GeometryType(inGeom) = 'POLYGON' OR GeometryType(inGeom) = 'MULTIPOLYGON') THEN

-- Only process if geometry is not valid, 
-- otherwise put out without change
    if not isValid(inGeom) THEN

-- create nodes at all self-intersecting lines by union the polygon boundaries
-- with the startingpoint of the boundary.  
      tmpLinestring := st_union(st_multi(st_boundary(inGeom)),st_pointn(boundary(inGeom),1));
      outGeom = buildarea(tmpLinestring);      
      IF (GeometryType(inGeom) = 'MULTIPOLYGON') THEN      
        RETURN st_multi(outGeom);
      ELSE
        RETURN outGeom;
      END IF;
    else    
      RETURN inGeom;
    END IF;


------------------------------------------------------------------------------
-- Clean Process for LINESTRINGS, self-intersecting parts of linestrings 
-- will be divided into multiparts of the mentioned linestring 
------------------------------------------------------------------------------
  ELSIF (GeometryType(inGeom) = 'LINESTRING') THEN

-- create nodes at all self-intersecting lines by union the linestrings
-- with the startingpoint of the linestring.  
    outGeom := st_union(st_multi(inGeom),st_pointn(inGeom,1));
    RETURN outGeom;
  ELSIF (GeometryType(inGeom) = 'MULTILINESTRING') THEN 
    outGeom := multi(st_union(st_multi(inGeom),st_pointn(inGeom,1)));
    RETURN outGeom;
  ELSIF (GeometryType(inGeom) = '<NULL>' OR GeometryType(inGeom) = 'GEOMETRYCOLLECTION') THEN 
    RETURN NULL;
  ELSE 
    RAISE NOTICE 'The input type % is not supported %',GeometryType(inGeom),st_summary(inGeom);
    RETURN inGeom;
  END IF;     
End;$BODY$
  LANGUAGE 'plpgsql' VOLATILE;
于 2010-01-07T23:58:06.753 に答える
2

オプション 1 は、各挿入の前にセーブポイントを作成し、失敗した場合はそのセーフポイントにロールバックすることですINSERT。

オプション 2 はWHERE、データを生成した元のクエリの条件としてチェック制約式をアタッチして、データがまったく選択されないようにすることです。

最良の答えは、テーブルのサイズ、障害のある行の相対的な数、およびこれを実行する速度と頻度によって異なります。

于 2010-01-07T21:39:45.643 に答える
0

ST_CollectionExtractを使用できると思います — (マルチ) ジオメトリを指定すると、指定された型の要素のみで構成される (マルチ) ジオメトリを返します。

ST_Intersection の結果を挿入するときに使用します。ST_Dump は、マルチポリゴンのコレクションを個々のジオメトリに分割します。次にST_CollectionExtract (theGeom, 3)、ポリゴン以外はすべて破棄します。

ST_CollectionExtract((st_dump(ST_Intersection(data.polygon, grid.polygon))).geom, )::geometry(polygon, 4326)

上記の 2 番目のパラメーターは次のよう3になります。1 == POINT, 2 == LINESTRING, 3 == POLYGON

于 2015-12-18T12:52:34.730 に答える