ERROR: function addgeometrycolumn is not unique

I have also encountered this problem and I think the OP may have solved it incorrectly. First, AddGeometryColumn is indeed overloaded. The three prototypes are:

    AddGeometryColumn(table_name, column_name, srid, type, dimension,use_typmod=true)    AddGeometryColumn(schema_name, table_name, column_name, srid, type, dimension, use_typmod=true)    AddGeometryColumn(catalog_name, schema_name, table_name, column_name, srid, type, dimension, use_typmod=true)

In my case, changing the following query:

SELECT AddGeometryColumn('public', 'facilities', 'walk_area', 4326, 'POLYGON', 2);

(which uses the second form) to this:

SELECT AddGeometryColumn('public', 'facilities', 'walk_area', 4326, 'POLYGON', 2, true);

solved the problem.

PostgreSQL supports function overloading.

With overloaded functions (like you obviously have), a call with just text literals (and no explicit type casts) can be ambiguous.

Normally, adding explicit type casts to your parameters literals fixes the problem. Arbitrary example:

SELECT my_fuc('foo'::text, 0.001::numeric, 123::int);

In your case, this call is ambiguous:

addGeometryColumn('vertices_tmp', 'the_geom', 4326, 'POINT', 2)

Be aware of these points:

• All unquoted identifiers are cast to lower case in Postgres.addGeometryColumn(...) is effectively the same as addgeometrycolumn(...).

• You may need to schema-qualify the function name to make it unambiguous. (Maybe you recently changed the search_path leading to a surprising result.

• If you do indeed have overloaded functions (not uncommon), add type casts to make your calls unambiguous.

• Defining parameter defaults for overloaded functions can make a previously unique call ambiguous.