Skip to content

Commit

Permalink
Replace "the_geom" with "geom" in PostGIS lessons (#9421)
Browse files Browse the repository at this point in the history 
Backports #9417
  • Loading branch information
@DelazJ
DelazJ authored Nov 27, 2024
2 parents 9021838 + 94275d2 commit 7d768eb
Show file tree
Hide file tree
Showing 4 changed files with 44 additions and 42 deletions.
42 changes: 22 additions & 20 deletions docs/training_manual/spatial_databases/geometry.rst
View file
Original file line number Diff line number Diff line change
Expand Up @@ -34,15 +34,15 @@ Try Yourself: :abbr:`★★☆ (Moderate level)`

::

alter table streets add column the_geom geometry;
alter table streets add column geom geometry;
alter table streets add constraint streets_geom_point_chk check
(st_geometrytype(the_geom) = 'ST_LineString'::text OR the_geom IS NULL);
insert into geometry_columns values ('','public','streets','the_geom',2,4326,
(st_geometrytype(geom) = 'ST_LineString'::text OR geom IS NULL);
insert into geometry_columns values ('','public','streets','geom',2,4326,
'LINESTRING');
create index streets_geo_idx
on streets
using gist
(the_geom);
(geom);


Now let's insert a linestring into our streets table. In this case we will
Expand All @@ -51,7 +51,7 @@ update an existing street record:
.. code-block:: sql
update streets
set the_geom = 'SRID=4326;LINESTRING(20 -33, 21 -34, 24 -33)'
set geom = 'SRID=4326;LINESTRING(20 -33, 21 -34, 24 -33)'
where streets.id=2;
Take a look at the results in QGIS. (You may need to right-click on the streets
Expand All @@ -69,7 +69,7 @@ polygons have at least four vertices, with the last and first being co-located:

.. code-block:: sql
insert into cities (name, the_geom)
insert into cities (name, geom)
values ('Tokyo', 'SRID=4326;POLYGON((10 -10, 5 -32, 30 -27, 10 -10))');
.. note:: A polygon requires double brackets around its coordinate list; this
Expand All @@ -78,7 +78,7 @@ polygons have at least four vertices, with the last and first being co-located:

.. code-block:: sql
insert into cities (name, the_geom)
insert into cities (name, geom)
values ('Tokyo Outer Wards',
'SRID=4326;POLYGON((20 10, 20 20, 35 20, 20 10),
(-10 -30, -5 0, -15 -15, -10 -30))'
Expand Down Expand Up @@ -116,14 +116,14 @@ Your updated people schema should look something like this:
house_no | integer | not null
street_id | integer | not null
phone_no | character varying |
the_geom | geometry |
geom | geometry |
city_id | integer | not null
Indexes:
"people_pkey" PRIMARY KEY, btree (id)
"people_name_idx" btree (name)
Check constraints:
"people_geom_point_chk" CHECK (st_geometrytype(the_geom) =
'ST_Point'::text OR the_geom IS NULL)
"people_geom_point_chk" CHECK (st_geometrytype(geom) =
'ST_Point'::text OR geom IS NULL)
Foreign-key constraints:
"people_city_id_fkey" FOREIGN KEY (city_id) REFERENCES cities(id)
"people_street_id_fkey" FOREIGN KEY (street_id) REFERENCES streets(id)
Expand All @@ -141,23 +141,23 @@ Your updated people schema should look something like this:

::

insert into people (name,house_no, street_id, phone_no, city_id, the_geom)
insert into people (name,house_no, street_id, phone_no, city_id, geom)
values ('Faulty Towers',
34,
3,
'072 812 31 28',
1,
'SRID=4326;POINT(13 -15)');

insert into people (name,house_no, street_id, phone_no, city_id, the_geom)
insert into people (name,house_no, street_id, phone_no, city_id, geom)
values ('IP Knightly',
32,
1,
'071 812 31 28',
1,
'SRID=4326;POINT(18 -24)');

insert into people (name,house_no, street_id, phone_no, city_id, the_geom)
insert into people (name,house_no, street_id, phone_no, city_id, geom)
values ('Rusty Bedsprings',
39,
1,
Expand Down Expand Up @@ -234,17 +234,17 @@ To avoid empty geometries, use:

.. code-block:: sql
where not st_isempty(st_intersection(a.the_geom, b.the_geom))
where not st_isempty(st_intersection(a.geom, b.geom))
.. figure:: img/qgis_001.png
:align: center

.. code-block:: sql
select st_intersection(a.the_geom, b.the_geom), b.*
select st_intersection(a.geom, b.geom), b.*
from clip as a, road_lines as b
where not st_isempty(st_intersection(st_setsrid(a.the_geom,32734),
b.the_geom));
where not st_isempty(st_intersection(st_setsrid(a.geom,32734),
b.geom));
.. figure:: img/qgis_002.png
:align: center
Expand All @@ -265,9 +265,9 @@ following command:

.. code-block:: sql
select ST_LineFromMultiPoint(st_collect(the_geom)), 1 as id
select ST_LineFromMultiPoint(st_collect(geom)), 1 as id
from (
select the_geom
select geom
from points
order by id
) as foo;
Expand Down Expand Up @@ -310,7 +310,9 @@ tablespaces:
CREATE TABLESPACE homespace LOCATION '/home/pg';
When you create a database, you can then specify which tablespace to use e.g.::
When you create a database, you can then specify which tablespace to use e.g.:

.. code-block:: bash
createdb --tablespace=homespace t4a
Expand Down
22 changes: 11 additions & 11 deletions docs/training_manual/spatial_databases/simple_feature_model.rst
View file
Original file line number Diff line number Diff line change
Expand Up @@ -40,7 +40,7 @@ Let's add a point field to our people table:

.. code-block:: sql
alter table people add column the_geom geometry;
alter table people add column geom geometry;
Add a constraint based on geometry type
Expand All @@ -53,8 +53,8 @@ You will notice that the geometry field type does not implicitly specify what
alter table people
add constraint people_geom_point_chk
check(st_geometrytype(the_geom) = 'ST_Point'::text
OR the_geom IS NULL);
check(st_geometrytype(geom) = 'ST_Point'::text
OR geom IS NULL);
This adds a constraint to the table so that it will only accept a point geometry
or a null value.
Expand All @@ -69,14 +69,14 @@ sure it has a constraint enforcing geometries to be polygons.
.. admonition:: Answer
:class: dropdown

::
.. code-block: sql
create table cities (id serial not null primary key,
name varchar(50),
the_geom geometry not null);
geom geometry not null);
alter table cities
add constraint cities_geom_point_chk
check (st_geometrytype(the_geom) = 'ST_Polygon'::text );
check (st_geometrytype(geom) = 'ST_Polygon'::text );
Expand All @@ -88,7 +88,7 @@ At this point you should also add an entry into the ``geometry_columns`` table:
.. code-block:: sql
insert into geometry_columns values
('','public','people','the_geom',2,4326,'POINT');
('','public','people','geom',2,4326,'POINT');
Why? :kbd:`geometry_columns` is used by certain applications to be aware of
which tables in the database contain geometry data.
Expand Down Expand Up @@ -124,7 +124,7 @@ Add an appropriate `geometry_columns` entry for your new cities layer
::

insert into geometry_columns values
('','public','cities','the_geom',2,4326,'POLYGON');
('','public','cities','geom',2,4326,'POLYGON');



Expand All @@ -135,7 +135,7 @@ Now that our tables are geo-enabled, we can store geometries in them:

.. code-block:: sql
insert into people (name,house_no, street_id, phone_no, the_geom)
insert into people (name,house_no, street_id, phone_no, geom)
values ('Fault Towers',
34,
3,
Expand Down Expand Up @@ -195,7 +195,7 @@ and add layers to your project as usual.
...............................................................................

Formulate a query that shows a person's name, street name and position (from the
the_geom column) as plain text.
geom column) as plain text.

.. admonition:: Answer
:class: dropdown
Expand All @@ -204,7 +204,7 @@ the_geom column) as plain text.

select people.name,
streets.name as street_name,
st_astext(people.the_geom) as geometry
st_astext(people.geom) as geometry
from streets, people
where people.street_id=streets.id;

Expand Down
20 changes: 10 additions & 10 deletions docs/training_manual/spatial_databases/spatial_queries.rst
View file
Original file line number Diff line number Diff line change
Expand Up @@ -19,18 +19,18 @@ point(X,Y) you can do this with:
select *
from people
where st_distance(the_geom,'SRID=4326;POINT(33 -34)') < 2;
where st_distance(geom,'SRID=4326;POINT(33 -34)') < 2;
Result:

.. code-block:: sql
id | name | house_no | street_id | phone_no | the_geom
id | name | house_no | street_id | phone_no | geom
----+--------------+----------+-----------+---------------+---------------
6 | Fault Towers | 34 | 3 | 072 812 31 28 | 01010008040C0
(1 row)
.. note:: the_geom value above was truncated for space on this page. If you
.. note:: geom value above was truncated for space on this page. If you
want to see the point in human-readable coordinates, try something similar
to what you did in the section "View a point as WKT", above.

Expand Down Expand Up @@ -60,7 +60,7 @@ much faster. To create a spatial index on the geometry column use:
CREATE INDEX people_geo_idx
ON people
USING gist
(the_geom);
(geom);
\d people
Expand All @@ -77,14 +77,14 @@ Result:
house_no | integer | not null
street_id | integer | not null
phone_no | character varying |
the_geom | geometry |
geom | geometry |
Indexes:
"people_pkey" PRIMARY KEY, btree (id)
"people_geo_idx" gist (the_geom) <-- new spatial key added
"people_geo_idx" gist (geom) <-- new spatial key added
"people_name_idx" btree (name)
Check constraints:
"people_geom_point_chk" CHECK (st_geometrytype(the_geom) = 'ST_Point'::text
OR the_geom IS NULL)
"people_geom_point_chk" CHECK (st_geometrytype(geom) = 'ST_Point'::text
OR geom IS NULL)
Foreign-key constraints:
"people_street_id_fkey" FOREIGN KEY (street_id) REFERENCES streets(id)
Expand All @@ -96,11 +96,11 @@ Modify the cities table so its geometry column is spatially indexed.
.. admonition:: Answer
:class: dropdown

::
.. code-block:: psql
CREATE INDEX cities_geo_idx
ON cities
USING gist (the_geom);
USING gist (geom);
Expand Down
2 changes: 1 addition & 1 deletion docs/user_manual/managing_data_source/supported_data.rst
View file
Original file line number Diff line number Diff line change
Expand Up @@ -517,7 +517,7 @@ The following example creates a GiST index::
\q to quit

gis_data=# CREATE INDEX sidx_alaska_lakes ON alaska_lakes
gis_data-# USING GIST (the_geom GIST_GEOMETRY_OPS);
gis_data-# USING GIST (geom GIST_GEOMETRY_OPS);
CREATE INDEX
gis_data=# VACUUM ANALYZE alaska_lakes;
VACUUM
Expand Down

0 comments on commit 7d768eb

Please sign in to comment.