query performance - Mailing list pgsql-general

From hmidi slim
Subject query performance
Date
Msg-id CAMsqVxvaucQ6p7f5RSE34uMwY0NQ=u4AaoabYTWeU57MWKxyzQ@mail.gmail.com
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Responses Re: query performance  (David Rowley <david.rowley@2ndquadrant.com>)
Re: query performance  (PT <wmoran@potentialtech.com>)
List pgsql-general
Hi, 
I have two tables: establishment which contains these columns: id, name, longitude, latitude, geom (Geometric column)
Product contains: id, name, establishment_id
First of all I want to select the establishment within a radius. 
I run this query:
select e.name, e1.name
from establishment as e, establishment as e1
where e.id <> e1.id
and e1.id = 1
and ST_DWithin(geom, ST_MakePoint(e1.longitude, e1.latitude)::geography, 1000)

The result of this query returns all the establishment within a radius 1KM from from a given establishment which has an id = 1.

After that I want to get the product's name of each establishment from the query's result.

Is there an other optimized solution to make a query such this:
select * from (
from establishment as e, establishment as e1
where e.id <> e1.id
and e1.id = 1
and ST_DWithin(geom, ST_MakePoint(e1.longitude, e1.latitude)::geography, 1000)) as tmp inner join product as p on p.establishment_id = tmp.id

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