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Thread: Field Rules Lost or dropped

  1. #1
    VAR csda1's Avatar
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    Ira J Perlow
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    Default Field Rules Lost or dropped

    I have a client that has lost the field rules to the primary table of a set (he never directly accesses the table itself). Most of the time he is using the runtime (A4V4 build 230), but could be using the full version.

    Shortly after the loss, I can see that the DDD, DDM, and DDX files have had their time stamp modified to about the time of the loss.

    Has anybody seen this and maybe isolated the issue at hand? Is there an Xbasic method that might accidently delete them as a side effect (mind you this rarely happens and the code is well tested)?

    Regards,

    Ira J. Perlow
    Computer Systems Design & Associates
    csda@mediaone.net

  2. #2
    Elliott Lester
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    Default RE: Field Rules Lost or dropped

    Ira:

    This has happened to us on a few occassions. It used to
    happy as a result of VXD errors and heap lock errors--sometimes with a error message, sometimes without. A major
    crash also did this once.

    I'll have Jim respond in more detail. I do not think that
    you can prevent it. We reduced some filtered indexes,
    and I know that A5v5 has eliminated this problem and has been working on A5v4 eliminiation.

    Back up Back up, but you know that.

    Good luck

  3. #3
    Jim Rowlen
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    Default RE: Field Rules Lost or dropped

    When we lost field rules (or they got scrambled or "moved" to adjacent fields...) it was, as far as I can remember, always the result of crashing when we had one or more corrupted memo field records. Doing the old memo-field shuffle and removing the bad memos fixed the problem.
    Probably the last thing you wanted to hear.

  4. #4
    Volunteer Moderator Peter.Greulich's Avatar
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    Peter Greulich
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    Default RE: Field Rules Lost or dropped

    I used to have this problem a lot in ver. 1 - when editing field rules in a set. It happened to me only once or twice in ver. 4. The last time it happened I may have been editing field rules while another instant of the table was open (you're not supposed to be able to this, but you can). Fortunately, the backup saved the day. In any case, very rare in ver. 4.

  5. #5
    VAR csda1's Avatar
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    Ira J Perlow
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    Default RE: Field Rules Lost or dropped

    No memo fields are being edited and they are in a child 1:many linked database anyway. No field rules were ever being edited.

    The files for the table (ddm, ddx, ddd) all look like they are the approximate correct size but each has grown by a small amount. It's almost like something tried to append to them and corrupted them. Nevertheless, all of the field rules and layouts (with the exception of 2 form layouts) have been cleared for that table.

    Restoring the files, corrects the problem. My client (who isn't doing anything unexpected) has seen this occur 3 separate times. I don't think I have ever seen it.

    Regards,

    Ira J. Perlow
    Computer Systems Design & Associates
    csda@mediaone.net

  6. #6
    "Certified" Alphaholic
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    Tom Cone Jr
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    Default RE: Field Rules Lost or dropped

    Ira,
    It's my understanding that the data dictionary files (including field rules) are themselves dbf and cdx files. One would think that they would be used read-only except when being explicitly modified during development. Yet when I review the file dates in my database folder I see that that they are 'last modified' on the same date as my regular dbf files. This suggests that Alpha Five opens and modifies them each time the tables are modified. Does this make sense?

    -- tom

  7. #7
    "Certified" Alphaholic
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    Finian Lennon
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    Default RE: Field Rules Lost or dropped

    Tom:

    If all you do is make data entry changes, the dd files date/time stamp is unaffected. If you modify the structure of the table in any way, change a field rule, add or change a layout, the dd date/time stamp will change. A change of field rule or layout will affect the date/time of the dd alone, not the dbf. A database compact will change the stamp of the dbfs, cdx's and the dd though not necessariy to exactly the same time since the reindex could take a long time, but the dd files will have effectively the same stamp because of the dictionary update.

    Finian

  8. #8
    Former Alpha Employee JerryBrightbill's Avatar
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    Jerry Brightbill
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    Default RE: Field Rules Lost or dropped

    Tom and Finian,

    I have noticed the same thing. Just did a little test. Entered a little data into a table. Only the time date stamp for the .dbf and cdx. files changed. Packed the table. Now all of the table files have a new time date stamp including the data dictionary files. Obviously, A5 opens and closes the data dictionary files for certain operations. If data can get corrupted due to hardware problems in the .dbf files, it seems reasonable that the data dictionaries can also get corrupted whenever A5 opens and closes them. Maybe this explains why long index names (saved in the data dictionary) seems to occasionaly give problems.

    Jerry

  9. #9
    "Certified" Alphaholic
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    Tom Cone Jr
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    Default RE: Field Rules Lost or dropped

    Finian, thanks for clarifying.

    Once again I see that I JTWCOID*.

    -- tom


    *(Jumped To Wrong Conclusion On Insufficient Data)

  10. #10
    nick marodis
    Guest

    Default RE: Field Rules Lost or dropped

    I have had this occur after a database compact and not all the time, thats about it


    Nick

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