Re: Creating index does not make any change in query plan.
От | Shridhar Daithankar |
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Тема | Re: Creating index does not make any change in query plan. |
Дата | |
Msg-id | 3E50F492.26732.915C9CB@localhost обсуждение исходный текст |
Ответ на | Re: Creating index does not make any change in query plan. (Deepa <kdeepa@midascomm.com>) |
Ответы |
Re: Creating index does not make any change in query plan.
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Список | pgsql-general |
On 17 Feb 2003 at 14:43, Deepa wrote: > On Mon, 17 Feb 2003, Shridhar Daithankar wrote: > Actually the indexed field is an bigint field. But when a query plan is > did on a selection using indexed field as a string it actually uses the > index. Otherwise, it does a ordinary query plan (i.e an non indexed query > plan). > > > > > What would be good in planner is to have field promotion like in C/C++, > > smallint->bigint->float->double as and when required. That would help a hell > > lot many people.. > > > > Will you please tell me how does the field promotion helps in planner. when you say id=2, it uses default int type which is smallint, AFAIK. So smallint != bigint and hence planner does not consider using index. When it is a string, conversion takes place which is to bigint because of field you are comparing against. Now bigint == bigint and hence planner uses the index. With field promotion, planner would convert smallint to bigint and hence will use the index if appropriate. Please correct me if I am wrong. This is what my impressions are from listening to list. HTH Bye Shridhar -- QOTD: On a scale of 1 to 10 I'd say... oh, somewhere in there.
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