At 10:30 PM 03-03-02 +0000, you wrote:

>On a production database which has been running rock solid for 18
>months, I have had data corruption twice in the last two weeks.
>
>The server log says
>
> internal gds software consistency check (decompression
>overran buffer (179))
>
>Server is NT4. DB version is IB 5.6. Database size is modest (110
>mb). Largest tables about 120k records.
>
>Validation finds no errors unless I check Validate Record Fragments.
>It refuses to back up (failing with the same error report) unless I
>first remove all indexes and foreign keys.
>
>The data corruption affects one or two records, and on each occasion
>they have been in different tables.
>
>Can anyone tell me what the error means, and what is likely to be
>causing it?

Just one place to look: do you have more generators defined than can fit
onto a single database page?

(I think) you divide your page_size (in bytes) by 32 in IB 5.6 and the
number is something less than int(that number). You need to count all
generators, not just those that are actively in use. So, for a db with a
page_size of 1024, you will max out at around 31 generators, give or take.

Ann posted the exact calculations a few months ago when the bug was
discovered (and fixed) in Firebird - you should be able to find them in the
list archive at the atkin mirror.

regards,
Helen


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