Multiple queries OR one and big
От | Alex Dovlecel |
---|---|
Тема | Multiple queries OR one and big |
Дата | |
Msg-id | E18ItiF-0002aB-00@ford.kbs.twi.tudelft.nl обсуждение исходный текст |
Список | pgsql-jdbc |
Hello all, This is a little bit out of topic but is related to jdbc. I have a database containing three tables : Route, RouteItem and RouteItemStop (Route : 1 -- n RouteItems 1 -- n RouteItemStops ). Hope you see the picture. :o) I want to obtain a route with a specific ID. I have two ways of implementing it: 1) one big sql join statement that links all those 3 tables. The problem will be the huge ammount of data (like all the Route data will be repeated for n^2 times , the same data). The advantage: only one query. 2) join by route and routeitem and then get all the routeItemStops for each route item. This means n+1 queries. Advantage : don't have all that ammount of inutile data sent from sql server. Disadvantage: n+1 sql statements to be executed, instead of only one. Is there any 'better' solution. If not, what should I choose? (don't have the experience and I don't know how psql sends a join query: optimised, not optimised)... For now join is just Where route.id = route_item.route_id. If I am going to use the JOIN sql command, will that be faster and better? Why ? Tx dovle
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