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Re: Sequence Scan vs. Index scan

From: "Reimer" <carlosreimer(at)terra(dot)com(dot)br>
To: "Fernando Lujan" <fernando(dot)lujan(at)mandic(dot)com(dot)br>,<pgsql-performance(at)postgresql(dot)org>
Subject: Re: Sequence Scan vs. Index scan
Date: 2006-03-21 18:23:08
Message-ID: 001a01c64d14$80f4a840$8b00000a@reimer (view raw or flat)
Thread:
Lists: pgsql-performance
Fernando,

If you need to read all the table for example it would be better to read 
only the data pages instead of read data and index pages.

Reimer

----- Original Message ----- 
From: "Fernando Lujan" <fernando(dot)lujan(at)mandic(dot)com(dot)br>
To: <pgsql-performance(at)postgresql(dot)org>
Sent: Tuesday, March 21, 2006 3:08 PM
Subject: [PERFORM] Sequence Scan vs. Index scan


> Hi guys,
>
> I'm trying to figure out when Sequence Scan is better than Index Scan. I 
> just want to know this because I disabled the sequence scan in postgresql 
> and receive a better result. :)
>
> Two tables.
>
> Table 1 (1 million rows )
> -----------
> id
> text
> table2_id
>
> Table 2 (300 thousand rows)
> ----------
> id
> text 2
>
> When I join these two tables I have a sequence_scan. :(
>
> Thanks in advance.
>
> Fernando Lujan
>
> ---------------------------(end of broadcast)---------------------------
> TIP 6: explain analyze is your friend
> 


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