Hi
I have a latiude and longitude for a city and latitude, longitude foreach
hotel in hotels table.
I have to reitreive 20 hotels nearby to that city in 25 miles. The below is
the query I am using to check the distance. But the query is slow because of
distance calulation on fly and order by distance.
Can anybody help me how can I improve performance by refining lat and long
data.
v_point is the city lat and long.(point(citylong citylat))
SELECT pr.property_id
, pr.property_type As property_type_id
, pr.property_name
,round (DISTANCE( v_point:: geometry,
POINTFromText('Point(' ||pr.long ||' ' ||
pr.lat||')')::geometry) *69.055) as CityToHotelDistance
FROM property.property pr
INNER JOIN place p ON (pr.place_id = p.place_id)
INNER JOIN placedetail pd ON (p.place_id = pd.place_id)
LEFT OUTER JOIN property.vw_property_price vwp ON (vwp.property_id =
pr.property_id)
WHERE DISTANCE( v_point :: geometry,
POINTFromText('Point(' ||pr.long ||' ' ||
pr.lat||')')::geometry) < .4 AND pr.place_id != p_place_id
AND (pr.status_type_id is null OR pr.status_type_id = 0)
ORDER BY DISTANCE( v_point :: geometry,
POINTFromText('Point(' ||pr.long ||' ' ||
pr.lat||')')::geometry)
offset 0 LIMIT 20;
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TIP 6: explain analyze is your friend
