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  • 1.  How to decode value of ifx_replcheck

    Posted 03/24/26 06:44 AM

    Hello, can someone help with decoding value in ifx_replcheck? - I have read in docs it is timestamp plus row version but need more precisely.

    We re using ifx_replcheck to identify changed rows since last recorded values for rows. Currently we are looking for why ifx_replcheck is different on table row where it seems values in all columns are the same. Table has insert, delete, update trigger defined. And one explanation could be the row is updated a couple of times but finally has the same value as when its state was recently recorded.

    So we need to know when the change in ifx_replcheck was done

    Thank you



    ------------------------------
    Milan
    ------------------------------


  • 2.  RE: How to decode value of ifx_replcheck

    Posted 03/24/26 08:55 AM

    Milan:

    You are confusing the ifx_replcheck shadow column with the two VERCOLS shadow columns ifx_insert_checksum and ifx_row_version. The ifx_replcheck shadow column is a single column that just has a pseudo-timestamp in it. That value will always change when the row is updated whether with the same values or different values or even if it was deleted and re-inserted with the same values.

    Just for completeness, the VERCOLS column ifx_insert_checksum contains a checksum of the row as it was when the row was inserted and does not change when the row is updated. The ifx_row_version starts at 1 and is incremented whenever the row is updated. 

    So, here are the scenarios describing the behavior of the VERCOLS shadow columns:

    • Row was deleted and reinserted with the same values:
      The ifx_row_version will be 1 and the ifx_insert_checksum will be the same.
    • Row was deleted and reinserted with different values:
      The  ifx_row_version will be 1 and the ifx_insert_checksum will be different
    • Row was updated to the same values:
      The ifx_row_version will have increased and the ifx_insert_checksum will be unchanged.
    • Row was updated to different values in one or more columns:
      The ifx_row_version will have increased and the ifx_insert_checksum will be unchanged.

    Art



    ------------------------------
    Art S. Kagel, President and Principal Consultant
    ASK Database Management Corp.
    www.askdbmgt.com
    ------------------------------



  • 3.  RE: How to decode value of ifx_replcheck

    Posted 03/24/26 09:44 AM
    Thank you Art for explanation of VERCOLS, it is useful. We use only ifx_replcheck - so there no logic in its value, just values which is different on each update even with the same value.

    Obsah obrázku text, klipart Popis byl vytvořen automaticky

    Milan Rafaj

    Senior Lead, Infrastructure/Cloud Architecture

    Kyndryl Consult

    +420 737 264 248

    www.kyndryl.cz

     

    Planned absence/Plánovaná nepřítomnost:  5-8.6., 5-16.7, 31.7.-11.8.2026

     

    Kyndryl Česká republika, spol. s r. o.

    Sídlo: Praha 4, Chodov, V Parku 2308/8, PSČ: 148 00,

    IČ: 14890992

    Zapsaná v obchodním rejstříku, vedeném Městským soudem v Praze (oddíl C, vložka 339277)

    Registered address: Prague 4, Chodov, V Parku, 2308/8, Zip code: 148 00

    Company ID: 14890992

    Entered in the Commercial Register maintained by the Municipal Court in Prague (Part C, Entry 339277)

    -- 

     




    Original Message


  • 4.  RE: How to decode value of ifx_replcheck

    Posted 03/24/26 09:43 AM

    Hi Milan,

    try dbinfo('UTC_TO_DATETIME', ifx_bit_rightshift(ifx_replcheck, 32)).

    Yes, ifx_replcheck does contain last update time which also enables "cdr check --since" functionality.
    (It does not for pre-existing, still unmodified data in case REPLCHECK got added using ALTER TABLE.)

    HTH,
     Andreas



    ------------------------------
    Andreas Legner
    Informix Dev
    HCL Software
    ------------------------------



  • 5.  RE: How to decode value of ifx_replcheck

    Posted 03/24/26 10:07 AM
    Thank you Andreas, very useful. We got timestamps now.

    Obsah obrázku text, klipart Popis byl vytvořen automaticky

    Milan Rafaj

    Senior Lead, Infrastructure/Cloud Architecture

    Kyndryl Consult

    +420 737 264 248

    www.kyndryl.cz

     

    Planned absence/Plánovaná nepřítomnost:  5-8.6., 5-16.7, 31.7.-11.8.2026

     

    Kyndryl Česká republika, spol. s r. o.

    Sídlo: Praha 4, Chodov, V Parku 2308/8, PSČ: 148 00,

    IČ: 14890992

    Zapsaná v obchodním rejstříku, vedeném Městským soudem v Praze (oddíl C, vložka 339277)

    Registered address: Prague 4, Chodov, V Parku, 2308/8, Zip code: 148 00

    Company ID: 14890992

    Entered in the Commercial Register maintained by the Municipal Court in Prague (Part C, Entry 339277)

    -- 

     




    Original Message


  • 6.  RE: How to decode value of ifx_replcheck

    Posted 03/25/26 05:16 AM
    Hello Andreas, 

    One more question - has 2nd part of ifx_replcheck also some useful information which can be used for further investigation

    Thanks a lot.

    Obsah obrázku text, klipart Popis byl vytvořen automaticky

    Milan Rafaj


    -- 

     




    Original Message


  • 7.  RE: How to decode value of ifx_replcheck

    Posted 03/26/26 11:48 AM

    Hi Milan,

    the lower 4 bytes actually are 2 * 2 bytes, first one being the last updating server's id (group number), second one a version counter.

    HTH,
     Andreas



    ------------------------------
    Andreas Legner
    Informix Dev
    HCL Software
    ------------------------------

    Original Message


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