Re: Fetch a single record

Поиск
Список
Период
Сортировка
От Peter Eisentraut
Тема Re: Fetch a single record
Дата
Msg-id 200312092121.37830.peter_e@gmx.net
обсуждение исходный текст
Ответ на Fetch a single record  (david_shadovitz@xontech.com (David Shadovitz))
Список pgsql-sql
David Shadovitz wrote:
> I'm looking for the fastest way to fetch a single record from a
> table. I don't care what record it is.
>
> Here are two techniques I've explored:
>
> 1. Use LIMIT
> SELECT * FROM myTable LIMIT 1
>
> 2. Get a valid OID and then get the record.
> SELECT MIN(oid) AS anOID FROM myTable
> SELECT * FROM myTable WHERE oid = anOID
>
> The 1st technique is slow.  (I think PostgreSQL fetches all records
> and then returns just one.)  The 2nd is faster, but not fast enough.

This is hard to believe.  The first technique should be the fasted, but 
might suffer from a bad plan.  Please make sure that you have run 
ANALYZE, and then post EXPLAIN ANALYZE output.



В списке pgsql-sql по дате отправления:

Предыдущее
От: jeff@dnuk.com
Дата:
Сообщение: How to specify the beginning of the month in Postgres SQL syntax?
Следующее
От: "David B"
Дата:
Сообщение: Faster performance when using where cust_id = '123' vs cust_id = 123. Does 7.4 fix this??