title: ERROR: function addgeometrycolumn is not unique
body: <p>I am trying to use the following function;</p>
  
  <pre><code>SELECT Assign_vertex_id('ways', 0.00001, 'the_geom', 'gid')
  </code></pre>
  
  <p>but for some reason it is giving me the following error;</p>
  
  <pre><code>NOTICE:  CREATE TABLE will create implicit sequence "vertices_tmp_id_seq" for serial column "vertices_tmp.id"
  CONTEXT:  SQL statement "CREATE TABLE vertices_tmp (id serial)"
  PL/pgSQL function "assign_vertex_id" line 15 at EXECUTE statement
  ERROR:  function addgeometrycolumn(unknown, unknown, integer, unknown, integer) is not unique
  LINE 1: SELECT addGeometryColumn('vertices_tmp', 'the_geom', 4326, '...
                 ^
  HINT:  Could not choose a best candidate function. You might need to add explicit type casts.
  QUERY:  SELECT addGeometryColumn('vertices_tmp', 'the_geom', 4326, 'POINT', 2)
  CONTEXT:  PL/pgSQL function "assign_vertex_id" line 24 at EXECUTE statement
  
  ********** Error **********
  
  ERROR: function addgeometrycolumn(unknown, unknown, integer, unknown, integer) is not unique
  SQL state: 42725
  Hint: Could not choose a best candidate function. You might need to add explicit type casts.
  Context: PL/pgSQL function "assign_vertex_id" line 24 at EXECUTE statement
  </code></pre>
  
  <p>Now from what I found it has to be something with old PostGIS signatures around.Infect when I ran The following command;</p>
  
  <pre><code>select proname, proargnames from pg_proc where proname = 'addgeometrycolumn'; 
  </code></pre>
  
  <p>The result was this;</p>
  
  <pre><code>pg_proc returns 6 rows.
  
  Three rows with column proargnames  returning a blank or (null) value
  </code></pre>
  
  <p>Can someone help me? Is it something that has to do with old postgis signitures? if so, how can I fix it?</p>
  
  <p>Thanks</p>