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Re: Fwd: Indexes (Disk space)

From: jose fuenmayor <jafn82(at)gmail(dot)com>
To: Aldor <an(at)mediaroot(dot)de>, pgsql-admin(at)postgresql(dot)org
Subject: Re: Fwd: Indexes (Disk space)
Date: 2005-08-24 12:43:35
Message-ID: 69f2062a05082405432fd92c92@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-admin
Ok I understand but I need to know the size of the index before i create it
I need to know  how much space it will ocupy (before actually create
the index, having the information of the table on wich I will build
the index), is this possible?
thanks in advance to everyone that can help me.

On 8/23/05, Aldor <an(at)mediaroot(dot)de> wrote:
> select * from pg_class;
> 
> or
> 
> select relname, relpages from pg_class where relname = '[index-name]';
> 
> the pages give you the information about the space the index uses, a
> page has 8kb.
> 
> [...]Every table and index is stored as an array of pages of a fixed
> size (usually 8Kb, although a different page size can be selected when
> compiling the server). In a table, all the pages are logically
> equivalent, so a particular item (row) can be stored in any page. In
> indexes, the first page is generally reserved as a metapage holding
> control information, and there may be different types of pages within
> the index, depending on the index access method. [...]
> 
> Source-URL:
> http://www.postgresql.org/docs/8.0/interactive/storage-page-layout.html
> 
> jose fuenmayor wrote:
> > ---------- Forwarded message ----------
> > From: jose fuenmayor <jafn82(at)gmail(dot)com>
> > Date: Aug 22, 2005 1:37 PM
> > Subject: Indexes (Disk space)
> > To: pgsql-admin(at)postgresql(dot)org
> >
> >
> > Hi all,
> > I have the following question.
> > Is there anyway for me to know how much space on disk will ocupy an
> > index, created in a determined row or rows of a table?, anything like
> > a rule, formula, calculation? that allow me to know in advance how
> > much space will the index use before actually created it.
> >
> > I aprecciate all the help you can give me
> >
> > Thanks in advance.
> >
> > ---------------------------(end of broadcast)---------------------------
> > TIP 1: if posting/reading through Usenet, please send an appropriate
> >        subscribe-nomail command to majordomo(at)postgresql(dot)org so that your
> >        message can get through to the mailing list cleanly
> >
>

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Next:From: AldorDate: 2005-08-24 13:51:30
Subject: Re: Fwd: Indexes (Disk space)
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Subject: ERROR: _mdfd_getrelnfd: cannot open relation pg_class: No such file or directory

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