Julian Hyde created CALCITE-2160:
------------------------------------
Summary: Spatial grid index
Key: CALCITE-2160
URL: https://issues.apache.org/jira/browse/CALCITE-2160
Project: Calcite
Issue Type: Bug
Reporter: Julian Hyde
Assignee: Julian Hyde
Recognize materialized views that convert a geometry into a grid of rectangles,
and use such materialized views for point-to-polygon and polgyon-to-polygon
joins.
Implement the [ST_MakeGrid|http://www.h2gis.org/docs/dev/ST_MakeGrid] and
[ST_MakeGridPoints|http://www.h2gis.org/docs/dev/ST_MakeGridPoints] functions.
Add a test data set based upon western U.S. states and national parks. Given a
materialized view
{code}CREATE MATERIALIZED VIEW StateGrids (name, x, y, PRIMARY KEY (name)) AS
SELECT s.name, ST_XMin(g.the_geom), ST_YMin(g.the_geom)
FROM States AS s
CROSS APPLY TABLE(ST_MakeGrid(s.geom, 1, 1)) AS g{code}
and a similar materialized view ParkGrids on Parks, the query
{code}SELECT p.name AS park, s.name AS state
FROM Parks AS p
JOIN States AS s ON ST_Overlaps(s.geom, p.geom)
ORDER BY 1, 2{code}
should return
{noformat}
Park State
============ =====
Death Valley CA
Death Valley NV
Yellowstone ID
Yellowstone MT
Yellowstone WY
Yosemite CA
{noformat}
and should semi-join to the {{StateGrids}} and {{ParkGrids}} tables to reduce
the size of the input before applying St_Overlaps: {code}SELECT p.name AS park,
s.name AS state
FROM Parks AS p
JOIN States AS s ON ST_Overlaps(s.geom, p.geom)
WHERE (p.name, s.name) IN (
SELECT DISTINCT pg.name, sg.name
FROM ParkGrids AS pg
JOIN StateGrids AS sg ON pg.id = sg.id){code}
Note the semi-join, to remove duplicates in case a park and a state have
several cells that overlap.
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
