Re: Can this be indexed?
От | Jerry III |
---|---|
Тема | Re: Can this be indexed? |
Дата | |
Msg-id | _Vljd.7851$O11.4984@newsread3.news.pas.earthlink.net обсуждение исходный текст |
Ответ на | Can this be indexed? ("Net Virtual Mailing Lists" <mailinglists@net-virtual.com>) |
Ответы |
Re: Can this be indexed?
|
Список | pgsql-general |
But if you do build an index over "id" then pgsql would only have to do a sequential scan on that index, which might be a lot faster if your table contains a lot of other data, won't it? Jerry ""Ed L."" <pgsql@bluepolka.net> wrote in message news:200411060930.30859.pgsql@bluepolka.net... > On Saturday November 6 2004 7:34, Net Virtual Mailing Lists wrote: >> Is there a way to create an index that would make this query be efficient >> and not perform a sequential scan? >> >> SELECT count(*) AS count,id FROM sometable GROUP BY id; >> >> .. I've considered creating a rule on this table which would put the >> results of this into another table anytime it is updated, but I thought >> there might be an easier way. > > Since you have no "WHERE" clause and you want to group by id, I believe > pgsql has to scan all id values. Those id values are only fully stored in > the table, so I don't think so. > > Ed > > > ---------------------------(end of broadcast)--------------------------- > TIP 7: don't forget to increase your free space map settings >
В списке pgsql-general по дате отправления: