Re: How does Index Scan get used

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От Oliver Elphick
Тема Re: How does Index Scan get used
Дата
Msg-id 1014406374.13241.2406.camel@linda
обсуждение исходный текст
Ответ на Re: How does Index Scan get used  (Oliver Elphick <olly@lfix.co.uk>)
Ответы Re: How does Index Scan get used  (Tom Lane <tgl@sss.pgh.pa.us>)
Список pgsql-sql
On Fri, 2002-02-22 at 18:08, Oliver Elphick wrote:
> PostgreSQL thinks there are only 10 rows in the table.  Therefore it
> will not choose an index scan because for so few rows it is bound to be
> more expensive than a sequential scan.

But then I saw Tom's mail saying that it does use the index.  How is
that?  Surely these few values would all be brought in in one single
disk read?

-- 
Oliver Elphick                                Oliver.Elphick@lfix.co.uk
Isle of Wight                              http://www.lfix.co.uk/oliver
GPG: 1024D/3E1D0C1C: CA12 09E0 E8D5 8870 5839  932A 614D 4C34 3E1D 0C1C
    "The LORD bless thee, and keep thee; The LORD make his     face shine upon thee, and be gracious unto thee; The
LORD lift up his countenance upon thee, and give thee      peace."              Numbers 6:24-26 
 



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