Re: simultaneous multiple requests to very simple database

Discussion in 'Python' started by Eric S. Johansson, Jan 18, 2005.

  1. Robert Brewer wrote:
    > Eric S. Johansson wrote:
    >
    >>I have an application where I need a very simple database,
    >>effectively a very large dictionary. The very large
    >>dictionary must be accessed from multiple processes
    >>simultaneously. I need to be able to lock records within
    >>the very large dictionary when records are written to.

    >
    >
    > Just to clarify, you want shared-read until a write, at which point you
    > want to lock just the item being written? Or would page or table locking
    > be acceptable at that point?


    just the item/record. I'm doing arrival rate calculations. each record
    contains a set of arrival times and I am rewriting the record every time
    a new entry arrives. complete page or table locking will work in the
    sense that it will prevent collisions but it will have an increasing
    impact as load and simultaneous table but not record accesses increase.

    ---eric
    Eric S. Johansson, Jan 18, 2005
    #1
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  2. On Tue, 18 Jan 2005 12:57:21 -0500, Eric S. Johansson <>
    wrote:

    > Robert Brewer wrote:
    >> Eric S. Johansson wrote:
    >>
    >>> I have an application where I need a very simple database, effectively
    >>> a very large dictionary. The very large
    >>> dictionary must be accessed from multiple processes
    >>> simultaneously. I need to be able to lock records within
    >>> the very large dictionary when records are written to.

    >> Just to clarify, you want shared-read until a write, at which point
    >> you
    >> want to lock just the item being written? Or would page or table locking
    >> be acceptable at that point?

    >
    > just the item/record. I'm doing arrival rate calculations. each record
    > contains a set of arrival times and I am rewriting the record every time
    > a new entry arrives. complete page or table locking will work in the
    > sense that it will prevent collisions but it will have an increasing
    > impact as load and simultaneous table but not record accesses increase.
    >
    > ---eric
    >


    Use Firebird as sql backend. Is designed as you request (readers not lock
    writers and writers not lock readers). Google for "firebird optimistic
    lock".

    Off course, you have python driver: http://kinterbasdb.sf.net and can
    deploy on windows and linux with a very little footprint.

    --
    Olaf Zetanien
    Olaf Zetanien, Jan 19, 2005
    #2
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  3. Eric S. Johansson

    Tim Jarman Guest

    Olaf Zetanien wrote:

    <snip>
    >
    > Use Firebird as sql backend. Is designed as you request (readers not lock
    > writers and writers not lock readers). Google for "firebird optimistic
    > lock".
    >
    > Off course, you have python driver: http://kinterbasdb.sf.net and can
    > deploy on windows and linux with a very little footprint.
    >


    And OS X. But it fails the OP's "no SQL" test.

    --
    Website: www DOT jarmania FULLSTOP com
    Tim Jarman, Jan 19, 2005
    #3
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