IDS Forum

Re: Page size x Row Size

Posted By: Art Kagel
Date: Tuesday, 24 July 2012, at 9:06 a.m.

In Response To: RE: Page size x Row Size (André Luiz Rufino)

Keep in mind that VARCHAR and LVARCHAR are variable length, so the actual
row sizes are likely to be much smaller than the defined column length and
if you have MAX_FILL_DATA_PAGES set to 1 in your ONCONFIG file then rows
will continue to be added to a page as long as the actual length of the row
fits until more than 90% of the page would be consumed by the insert (with
MAX_FILL_DATA_PAGES set to 0 or unset rows are only added to a page if the
maximum length of the row would fit). On one system I know, aud_cmd_list,
which has an LVARCHAR(8192) column, the actual average lenght of the
aus_cmd_exe column in the table is 95 bytes with a minimum of 44 and a
maximum of 1114 bytes, so there are from 2 to 45 rows on a page even though
the maximum length of the variable length row would take up almost four
full pages at 2K/page.

That said, you can move the sysadmin database to a dbspace with wider pages
if your experience is different. You can find a link to a developer works
article about moving sysadmin in the forums if you search.

Art

Art S. Kagel
Advanced DataTools (www.advancedatatools.com)
Blog: http://informix-myview.blogspot.com/

Disclaimer: Please keep in mind that my own opinions are my own opinions
and do not reflect on my employer, Advanced DataTools, the IIUG, nor any
other organization with which I am associated either explicitly,
implicitly, or by inference. Neither do those opinions reflect those of
other individuals affiliated with any entity with which I am affiliated nor
those of the entities themselves.

On Tue, Jul 24, 2012 at 8:25 AM, André Luiz Rufino <andre_rufino@msn.com>wrote:

> Thanks for everyone,
> Take a look at this:
> create table "suporte".wb_teste_email ( mensagem lvarchar(30000) ) extent
> size
> 742 next size 76 lock mode row;
> That's a ERP table. But a got a lot of tables aus_???? and ph_????
> (sysadmin
> tables) that shows the same thing?!?!?
> Ok, I got it. Now I know what I can do with this table above. But how can I
> manage the sysadmin tables like those?
>
> Thanks again
> André Luiz Rufino
> > To: ids@iiug.org
> > From: frank_in_pr@hotmail.com
> > Subject: Re: Page size x Row Size [27775]
> > Date: Mon, 23 Jul 2012 21:34:30 -0400
> >
> > >
> > > On Mon, Jul 23, 2012 at 7:18 PM, FRANK J. COMPUTER
> > > <frank_in_pr@hotmail.com>wrote:
> > > > Most IDS page sizes are 4K, but some are 2K depending on the hardware
> and
> > > > IDS version.
> > >
> >
> > >On Mon, Jul 23, 2012 at 5:07 PM, Art Kagel <art.kagel@gmail.com> wrote:
> >
> > > Actually Frank, only AIX, Windows, and MAC OS-X use 4K pages as the
> > > default. All other platforms use a 2K page as the default. You can
> define
> > > larger page sizes in multiples of the platform default page up to 32K
> pages
> > > for all versions from 10.00 and later.
> > >
> >
> > >Up to 16 K, I think you'll find.
> >
> > Thanks for the correction, I'll remember that. Since I'm testing
> 11.70.TC5
> on
> > Windows, would there be any benefit in increasing the pagesize to 16K?
> Does
> a
> > larger pagesize mean that I can fit more rows read into a larger page
> size
> to
> > increase performance? My hardisk was formatted 64K cluster size.
> >
> >
> >
>
> *******************************************************************************
> > Forum Note: Use "Reply" to post a response in the discussion forum.
> >
>
>
>
> *******************************************************************************
> Forum Note: Use "Reply" to post a response in the discussion forum.
>
>

--20cf30244ca3b1670504c59306e4

Messages In This Thread

• Page size x Row Size
  André Luiz Rufino -- Monday, 23 July 2012, at 5:43 p.m.
  • Re: Page size x Row Size
    Fernando Nunes -- Monday, 23 July 2012, at 5:51 p.m.
  • Re: Page size x Row Size
    FRANK J. COMPUTER -- Monday, 23 July 2012, at 7:18 p.m.
    • Re: Page size x Row Size
      Art Kagel -- Monday, 23 July 2012, at 8:07 p.m.
      • Re: Page size x Row Size
        Jonathan Leffler -- Monday, 23 July 2012, at 9:18 p.m.
        • Re: Page size x Row Size
          FRANK J. COMPUTER -- Monday, 23 July 2012, at 9:34 p.m.
          • RE: Page size x Row Size
            André Luiz Rufino -- Tuesday, 24 July 2012, at 8:25 a.m.
            • Re: Page size x Row Size
              Art Kagel -- Tuesday, 24 July 2012, at 9:06 a.m.
            • RE: Page size x Row Size
              Alexandre Marini -- Tuesday, 24 July 2012, at 9:27 a.m.
  • Re: Page size x Row Size
    Art Kagel -- Monday, 23 July 2012, at 8:00 p.m.

IDS Forum is maintained by Administrator with WebBBS 5.12.