Subject RE: [firebird-support] how read commited is implemented
How versions are kept in file structure?
How long? Is it possible to configure time period to keep versions and/or
space allocated for versioning?

The issue is that the versioning is a real performance killer: various
strategies exist to deal with that. For example, the SQL table record can be
updated with a last version and previous versions kept in some linked list or
vice versa: a current version is kept in a list while table record contains
the last commited version: this makes a performance .difference for different

-----Original Message-----
From: Ann Harrison [mailto:aharrison@...]
Sent: 11. janĂșar 2004 18:52
Subject: Re: [firebird-support] how read commited is implemented

laimisnd wrote:

>Can anyone share information how FireBird is implementing read
>I am interested in the general model used(i.e. does writers block
>readers and vice versa, etc) and more details like what files or
>structures are involved internaly by the Firebird.
Firebird keeps back versions of records that have been updated or
deleted, and
has a way to determine which version of a record a specific
see. Readers don't block writers and writers don't block readers.




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