joins and indexes -- a=b or b=a?
От | will trillich |
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Тема | joins and indexes -- a=b or b=a? |
Дата | |
Msg-id | 20010328170111.B16380@mail.serensoft.com обсуждение исходный текст |
Ответы |
Re: joins and indexes -- a=b or b=a?
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Список | pgsql-general |
if you have a main table on which you're doing a linear scan: create table person ( id varchar(12), -- handle/id/login name varchar(30), gang int4 ); that joins another indexed table: create table gang ( id serial, name varchar(30), primary key(id) ); is there any significant difference in the following two queries: select p.id as handle, p.name as person, g.name as gang from person p, gang g where PERSON.GANG = GANG.ID ; -- as opposed to: select p.id as handle, p.name as person, g.name as gang from person p, gang g where GANG.ID = PERSON.GANG ; the only difference is GANG.ID=PERSON.GANG versus PERSON.GANG=GANG.ID in the WHERE clause. does it matter? -- It is always hazardous to ask "Why?" in science, but it is often interesting to do so just the same. -- Isaac Asimov, 'The Genetic Code' will@serensoft.com http://newbieDoc.sourceforge.net/ -- we need your brain! http://www.dontUthink.com/ -- your brain needs us!
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