too many versions... message

[Learn Softwares]

I have a table in Firebird with 319 fields and now I need to add 3 more fields, but I receive the message "too many versions". I also tried to delete some fields and I also receive this message. What can it be? How to solve?

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Atenciosamente,

Learn Softwares ®

[Gabor Boros]

Hi,

https://www.firebirdfaq.org/faq239

Gabor

[Mark Rotteveel]

On 20/02/2024 19:13, Learn Softwares wrote:
> I have a table in Firebird with 319 fields and now I need to add 3 more
> fields, but I receive the message "too many versions". I also tried to
> delete some fields and I also receive this message. What can it be? How
> to solve?

It sound like your software is making a lot of DDL changes to your
tables. A table can only be structurally modified 256 times. If you
exceed that count, you need to backup and restore your database with gbak.

This isn't about the number of fields or anything, but if you execute
certain ALTER TABLE commands, the format version of the table is
incremented, and this counter is 8-bit. These format versions are used
for the table data that is stored. When structurally modifying a table,
old records are not updated, but instead when they are read, they are
upgraded in-memory from the format version they were stored in to the
current format version.

Mark
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Mark Rotteveel

[Luigi Siciliano]

Il 21/02/2024 07:55, 'Mark Rotteveel' via firebird-support ha scritto:
> This isn't about the number of fields or anything, but if you execute
> certain ALTER TABLE commands, the format version of the table is
> incremented, and this counter is 8-bit. These format versions are used
> for the table data that is stored. When structurally modifying a
> table, old records are not updated, but instead when they are read,
> they are upgraded in-memory from the format version they were stored
> in to the current format version.
>

Those in memory updates can affect performance?

Thanks

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Luigi
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[Ann Harrison]

Very slightly.  Records are compressed before storage.  Decompression

is about the same cost as decompression plus bringing the format up

to the current verison.  If a record from an earlier format is updated, 

obviously, it's written in the new format.

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Luigi
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