Antwort: Re: [DB2-L] Rebind

Roy Boxwell

Antwort: Re: [DB2-L] Rebind
and if you want to check all of your statistics before you REBIND then run
a little freeware program called StatisticsHealthCheck
available free-of-charge from http://www.seg.de or
http://www.neonesoft.com


Roy Boxwell
SOFTWARE ENGINEERING GMBH
-Product Development-
Robert-Stolz-Strasse 5
40470 Duesseldorf/Germany
Tel. +49 (0)211 96149-0
Fax +49 (0)211 96149-35
E-mail [login to unmask email]
Homepage www.seg.de





"Jardine, Lawrence J" <[login to unmask email]>
Gesendet von: DB2 Data Base Discussion List <[login to unmask email]>
01.12.2006 01:56
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Thema: Re: [DB2-L] Rebind


REBIND (o
Sometimes working backwards is easier to understand.

REBIND (only) when you want access paths to change. Otherwise, why
bother?
Before you REBIND, make sure statistics are current: do RUNSTATS.
Before you do RUNSTATS, make sure you will get "good" statistics: REORG.

Put another way, for a heavy-loaded transaction environment with mostly
static SQL:
- REORG frequently.
- Do RUNSTATS only after reorgs (or inline with the REORG).
- REBIND rarely (only when you want different access paths).

For dynamic SQL and environments where the data is very volatile:
- Do RUNSTATS frequently.
- REORG as often as you can.
- REBIND doesn't apply for dynamic SQL.


Larry Jardine
Production DBA

-----Original Message-----
From: DB2 Data Base Discussion List [mailto:[login to unmask email] On
Behalf Of James Campbell
Sent: Thursday, November 30, 2006 7:31 PM
To: [login to unmask email]
Subject: Re: [DB2-L] Rebind

Necessary - in that will you get incorrect results if you do not rebind
- no. (Bugs excepted.)

Necessary - in that will you get improved performance - depends. There
are some situations where people have carefully crafted binds to get
optimal response and a rebind would undo the care; however it is also
possible to get better performance after a rebind.

Generally the ideal would be to re-bind into a dummy collection and
compare the PLAN_TABLE stuff for the production and dummy entries. If
they are the same, you don't need to rebind the production; if they are
different, determine which is better and act accordingly. If this is
after a RUNSTATS, you might find undesirable access paths - which might
be the signal to do a reorg.

As the production stuff was, presumably, rebound after the previous
reorg there should be little, if any change.

James Campbell

On 30 Nov 2006 at 9:43, Rambabu Vanama wrote:

> Is it necessary to do the REBIND after performing the REORG or
> RUNSTATS? I have always been thinking that we should perform Rebind
> after the Reorg/Runstats to see the effect of Reorg/Runstats. But I
> recently heard that it is not necessary to do the Rebind and could
> have negative impact if we do.
>
> Appreciate all your responses.
>
> -Rambabu Vanama
>

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