Joins and their efficiencies
От | Hadley Willan |
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Тема | Joins and their efficiencies |
Дата | |
Msg-id | 1049315977.1677.80.camel@atlas.sol.deeper.co.nz обсуждение исходный текст |
Ответы |
Re: Joins and their efficiencies
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Список | pgsql-general |
Hi All, I was doing a query yesterday, and implemented it two ways to see if there was a difference. The first was the more standard way of doing the query, by specifying the tables, and then linking them with AND x.id = y.object etc..... I ran this and there seemed to be a momentary pause of around one to one-half seconds before the result set returned. I decided to try the same query again, but this time using, LEFT JOIN to bring in the extra tables I wanted, it still had a few ANDs in there but only about half as much. I ran the query and the ResultSet returned instantly! Is it correct then to assume that a LEFT JOIN is more efficient than a straight join? Thanks. -- Hadley Willan > Systems Development > Deeper Design Limited. +64(7)377-3328 hadley.willan@deeperdesign.co.nz > www.deeperdesign.com > +64(21)-28-41-463 Level 1, 4 Tamamutu St, PO Box 90, TAUPO 2730, New Zealand.
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