Re: Seq scan vs index scan

Поиск
Список
Период
Сортировка
От Christophe Pettus
Тема Re: Seq scan vs index scan
Дата
Msg-id 5FE1E177-BFDB-4386-8DDC-02A652E71C86@thebuild.com
обсуждение исходный текст
Ответ на Seq scan vs index scan  (arun chirappurath <arunsnmimt@gmail.com>)
Список pgsql-general

> On Mar 22, 2024, at 20:55, arun chirappurath <arunsnmimt@gmail.com> wrote:
> I am trying to force query to use indexes  using query hints.

PostgreSQL does not have query hints.  Enabling index scans using parameters doesn't *disable* other types of query
nodes.

You can disable sequential scans using:

    SET enable_seqscan = off;

... but more importantly, why do you want to force an index scan?  Generally, PostgreSQL will pick a sequential scan
overan index scan if the table is small, or the number of rows that come back from the query are a significant
percentageof the rows of the table. 

If you would like a more detailed answer, it would be a good idea to post an execution plan of the query with:

    EXPLAIN ANALYZE SELECT * FROM users WHERE username = 'example_username';


В списке pgsql-general по дате отправления:

Предыдущее
От: arun chirappurath
Дата:
Сообщение: Seq scan vs index scan
Следующее
От: "David G. Johnston"
Дата:
Сообщение: Re: Seq scan vs index scan