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Thread: Cost performace question

Cost performace question

From
paulo matadr
Date:
Hi all have a dought about explain of postgres
Let's see:

Who have more cost for database:
Index Scan using xix3_movimento_roteiro_empresa on movimento_roteiro_empresa movimentor0_  (cost=0.00..73386.80 rows=5126 width=451)
  Index Cond: (mrem_ammovimento = 200906)
  Filter: ((ftgr_id = 26) AND ((mrem_icatualizarleitura IS NULL) OR (mrem_icatualizarleitura = 2)) AND (mrem_tmleitura IS NOT NULL))

or

Aggregate  (cost=26573.78..26573.79 rows=1 width=4)
  ->  Index Scan using xix4_movimento_roteiro_empresa on movimento_roteiro_empresa movimentor0_  (cost=0.00..26560.41 rows=5347 width=4)
        Index Cond: ((ftgr_id = 26) AND (mrem_ammovimento = 200906))



Im confused about who is the most import (colour red ou blue).

thanks







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Re: Cost performace question

From
"Kevin Grittner"
Date:
paulo matadr <saddoness@yahoo.com.br> wrote:

> Im confused about who is the most import (colour red ou blue).

For the benefit of those without an easy way to view email in http,
the first cost number was in red, the second in blue.

The first number is the cost to retrieve the first row, the second
number is the cost to retrieve the full set of rows.  Usually I'm
paying more attention to the second number.

-Kevin

Res: Cost performace question

From
paulo matadr
Date:
thanks i understand now,  i have other dought
Index Scan using xix3_movimento_roteiro_empresa on movimento_roteiro_empresa movimentor0_  (cost=0.00..73386.80 rows=5126 width=451)
what's this mean on red color above?



De: Kevin Grittner <Kevin.Grittner@wicourts.gov>
Para: pgsql-performance@postgresql.org; paulo matadr <saddoness@yahoo.com.br>
Enviadas: Sexta-feira, 10 de Julho de 2009 11:51:27
Assunto: Re: [PERFORM] Cost performace question

paulo matadr <saddoness@yahoo.com.br> wrote:

> Im confused about who is the most import (colour red ou blue).

For the benefit of those without an easy way to view email in http,
the first cost number was in red, the second in blue.

The first number is the cost to retrieve the first row, the second
number is the cost to retrieve the full set of rows.  Usually I'm
paying more attention to the second number.

-Kevin

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Re: Res: Cost performace question

From
Matthew Wakeling
Date:
On Fri, 10 Jul 2009, paulo matadr wrote:
> thanks i understand now,  i have other dought
> Index Scan using xix3_movimento_roteiro_empresa on movimento_roteiro_empresa movimentor0_  (cost=0.00..73386.80
> rows=5126 width=451)
> what's this mean on red color above?

Please don't assume that everyone receiving your mails uses a HTML mail
reader. In fact, recommended netiquette is to not send HTML mails at all.
Many people set their email programs to automatically reject (as spam) any
emails containing HTML.

Manually reading the HTML, it seems that you are referring to the
"width=451" part of the EXPLAIN result. Please read the manual at
http://www.postgresql.org/docs/8.4/interactive/using-explain.html

The width is the:

* Estimated average width (in bytes) of rows output by this plan node

Matthew

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