Re: [HACKERS] Transaction logging

>
> Your getting me excited about 6.5.  Is there a projected release date for
> 6.5?  Is there any information on transaction logging?  Is there anything I
> can do to help?  I am curious about these items because they will make my
> life much easier in the upcoming months as I migrate my application to
> Postgres.  Working around these could be very difficulty or near impossible.

    I've  spent  some  time  thinking  about transaction log. The
    first idea was to log queries and in some way. But I  had  to
    drop  that  approach  because  there are functions (and users
    could have written threir own ones too),  that  don't  return
    the  same result when the database later get's rolled forward
    (e.g.  anything  handling   date's/times).    And   OTOH   an
    application  could  SELECT  something  from the database that
    maybe got created by a sequence, and uses this value then  in
    another  INSERT.   But when recovering the database, it isn't
    guaranteed that all the data  will  get  the  same  sequences
    again (race conditions in concurrent queries). How should the
    transaction log now know that this one constant value in  the
    query   must  be  substituted  by  another  value  to  ensure
    referential integrity? Absolutely impossible.

    So the only way I see is to use some sort  of  image  logging
    from  inside  the  heap  access  methods.  Would be much more
    tricky to dump and recover.


Jan

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