Db2

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  • 1.  DB2_BCKP_PAGE_VERIFICATION

    Posted Thu April 08, 2021 09:47 AM

    Hi,

    It seems the DB2_BCKP_PAGE_VERIFICATION registry cannot be applied with -immediate flag. I would like sometimes to be able during a backup, to do a sanity check of my databases at the same time, but I cannot stop the applications in Production.

    What does prevent the -immediate flag to be used ?

    Best regards,

    JMB


    #Db2


  • 2.  RE: DB2_BCKP_PAGE_VERIFICATION

    Posted Mon March 30, 2020 01:21 PM

    Hi Michael,

    Thanks for your mail. Afaik, I trust first the IBM documentation and I was looking for the '-immediate' flag in the documentation for this registry. I am using 10.5 and 11.1

    If I do:

    db2set DB2_EVAL_UNCOMMITTED=ON

    db2set

    ==> will show you the DB2_EVAL_UNCOMMITTED is ON but it is not active yet, until db2 instance recycling. So a great lack here is : there is no db2set option to give you actual and deferred values like for DBM and DB CFG.

     

    Secondly, it appears the -im flag only applied to registries linked to 'SQL', from db2set -h

    -im | -immediate

             Indique que la mise à jour sera appliquée la prochaine fois qu'une instruction SQL sera compilée pour des variables de registre prenant en charge cette fonction.

    So there is no need finally to issue db2set DB2_BCKP_PAGE_VERIFICATION=on -im,  db2set DB2_BCKP_PAGE_VERIFICATION=on is sufficient

     

    I also found the db2set -info <Registry Name> command, that can give you, prevently, information about the registry.

    ==> Why not giving back a result message with db2set command ?

     

    From documentation, some examples:

    General registry
    DB2_SYSTEM_MONITOR_SETTINGS
    Changes to this variable will take effect immediately for all future compiled SQL statements. There is no need to restart the instance or to issue the db2set command with the -immediate parameter.
    db2set -info DB2_SYSTEM_MONITOR_SETTINGS
       Mod imméd prise en charge  : OUI
       Immédiat par défaut  :       OUI

    Miscellaneous
    DB2_BCKP_PAGE_VERIFICATION
    No indication
    db2set -info DB2_BCKP_PAGE_VERIFICATION
       Mod imméd prise en charge  : OUI
       Immédiat par défaut  :       OUI

    Query compiler variables
    DB2_ANTIJOIN
    Changes to this variable can take effect immediately for all future compiled SQL statements if the db2set command is issued with the -immediate parameter. You do not need to restart the instance.
    db2set -info DB2_ANTIJOIN
       Mod imméd prise en charge  : OUI
       Immédiat par défaut  :       NO ==> therefore the -im flag is mandatory to change the immediately

    PureScale
    DB2_DATABASE_CF_MEMORY
    DB2_DATABASE_CF_MEMORY can be changed dynamically, and a database manager restart is not required. (another way of phrasing the -im is not necessary)
    db2set -info DB2_DATABASE_CF_MEMORY
       Mod imméd prise en charge  : OUI
       Immédiat par défaut  :       OUI

     

    Why not cleaning up the documentation, and try to have a clear format as for DBM and DB CFG parameters ?

    Parameter type

            Configurable dynamically
            Configurable dynamically with -im flag
    Propagation class
        Statement boundary

     

    Best regards,

    JMB


    Original Message


  • 3.  RE: DB2_BCKP_PAGE_VERIFICATION

    Posted Thu April 08, 2021 09:47 AM

    Hi.  What Db2 version are you on?  It is a dynamic registry variable in that no db2stop/db2start is needed.  What makes you say that -immediate flag doesn't work?

    > db2start
    SQL1063N  DB2START processing was successful.

    > db2set DB2_BCKP_PAGE_VERIFICATION=on -immediate

    > db2set
    DB2_BCKP_PAGE_VERIFICATION=on
     

    Thanks.


    Original Message


  • 4.  RE: DB2_BCKP_PAGE_VERIFICATION

    Posted Thu April 08, 2021 09:47 AM
    Hi. I agree, I was also surprised that the reg var did not mention that it is dynamic. I think it would be helpful to mention whether a reg var is dynamic or not. There currently doesn't seem to be a standard for this but I will follow up with development and see if this can be done, at the very least for new reg vars.

    In general I also just issue 'db2set var=value', but as you it is tough to tell when it will take effect. If there are ones that you want to be dynamic then probably best to report to service. In this case DB2_BCKP_PAGE_VERIFICATION is dynamic so I'll look to get the docs updated.

    Thanks for pointing this out.
    Original Message