rooted spatial query with sub-select in OrientDB

问题

I am trying to put together a query to find nodes that are within 2km of a node in my graph. Say I have a dataset that marks some geoglyphs from the nazca lines:

Name,Latitude,Longitude
Hummingbird,-14.692131,-75.148892
Monkey,-14.706940,-75.138532
Condor,-14.697444,-75.126208
Spider,-14.694145,-75.122381
Spiral,-14.688277,-75.122746
Hands,-14.694459,-75.113881
Tree,-14.693898,-75.114520
Astronaut,-14.745222,-75.079755
Dog,-14.706401,-75.130788
Wing,-14.680309,-75.100385
Parrot,-14.689463,-75.107498

I have a spatial index created using:

CREATE INDEX GeoGlyph.index.Location 
ON GeoGlyph(Latitude,Longitude) SPATIAL ENGINE LUCENE

Now, I want to find the nodes within 2km of the "Hands" glyph, I can enter in this query by manually putting in the Lat/Long coordinates:

SELECT Name, Latitude, Longitude, $distance AS Distance 
FROM GeoGlyph 
WHERE [Latitude,Longitude,$spatial] 
NEAR [-14.694459,-75.113884,{"maxDistance":2}] 
ORDER BY Distance

I get the result:

+----+------+----------+----------+--------------------+
|#   |Name  |Latitude  |Longitude |Distance            |
+----+------+----------+----------+--------------------+
|0   |Hands |-14.694459|-75.113884|5.230883384236603E-6|   
|1   |Tree  |-14.693897|-75.11446 |0.08836486627516459 |
|2   |Spider|-14.694363|-75.12358 |1.0442063409276094  |
|3   |Spiral|-14.688309|-75.12276 |1.1754176535538237  |
|4   |Condor|-14.698346|-75.128334|1.6149944044266815  |
+----+------+----------+----------+--------------------+

So far, so good.

Since it's a bit of a pain to type in the coordinates, I'd much rather just look for glyphs within 2km using the Name field "Hands".

This is where I'm currently stuck. I think I should be able to use LET block to get what I want... but what I've tried so far isn't working:

SELECT *,$distance AS Distance 
FROM GeoGlyph 
LET $temp = (SELECT * FROM GeoGlyph WHERE Name = "Hands")
WHERE [Latitude,Longitude,$spatial] 
NEAR [$temp.Latitude, $temp.Longitude,{"maxDistance":2}] 
ORDER BY Distance

Any suggestions?

回答1:

I figured out the way to do it... if it's safe to assume that the field GeoGlyph.Name is unique, I can use first() in the NEAR clause:

SELECT *,$distance AS Distance 
FROM GeoGlyph 
LET $temp = (SELECT * FROM GeoGlyph WHERE Name = "Hands")
WHERE [Latitude,Longitude,$spatial] 
NEAR [first($temp).Latitude, first($temp).Longitude,{"maxDistance":2}] 
ORDER BY Distance

This seemed to do the trick.

orientdb {db=nazca.orientdb}> SELECT *,$distance AS Distance FROM GeoGlyph LET $temp = (SELECT * FROM GeoGlyph WHERE Name = "Hands") WHERE [Latitude,Longitude,$spatial] NEAR [first($temp).Latitude, first($temp).Longitude,{"maxDistance":2}] ORDER BY Distance

+----+-----+--------+----------+----------+------+-------------------+
|#   |@RID |@CLASS  |Latitude  |Longitude |Name  |Distance           |
+----+-----+--------+----------+----------+------+-------------------+
|0   |#25:5|GeoGlyph|-14.694459|-75.113884|Hands |0.0                |
|1   |#25:6|GeoGlyph|-14.693897|-75.11446 |Tree  |0.08836394983673491|
|2   |#25:3|GeoGlyph|-14.694363|-75.12358 |Spider|1.0442092937404572 |
|3   |#25:4|GeoGlyph|-14.688309|-75.12276 |Spiral|1.1754175925032648 |
|4   |#25:2|GeoGlyph|-14.698346|-75.128334|Condor|1.614998440581846  |
+----+-----+--------+----------+----------+------+-------------------+

I'm still not sure exactly how I'd do this if I couldn't rely on uniqueness of the Name field though. For example if I wanted to compute all the pairs of geoglyphs within 2km of each other...

来源：https://stackoverflow.com/questions/40942434/rooted-spatial-query-with-sub-select-in-orientdb