File locking / sempahore necessary in multi user environment?

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  • Scott Bryce
    #1

    File locking / sempahore necessary in multi user environment?

    I am creating a CGI application in Perl that uses an Access database. It
    will be hosted on an NT server. I have used flat file DBMs (tied hashes)
    on UNIX servers, but I am not familiar with how Access behaves in a
    multi-user environment.

    Will I need to use some sort of file locking/semaphore scheme, or does
    Access (or the ODBC drivers?) manage conflicts between multiple users? I
    want to avoid corruption of data should multiple users attempt to write
    to a table/record at the same time.

    If a semaphore is not normally needed, under what circumstances should I
    consider using one?

    Tags: None
    • Scott McDaniel
      #2
      Re: File locking / sempahore necessary in multi user environment?

      Access will handle the file locking internally. The locking scheme is, of
      course, dependant on how you setup Access/Jet and what parameters you set on
      your connection objects (ie. adLockPessimist ic, adLockOptimisti c, etc), what
      type of recordset (if any) you open, etc etc.

      How heavy will the transaction load be? Access works fine in a Web
      environment assuming most of your processes are analytical (i.e. lookup,
      reporting, etc). If you are going to be doing a LOT of transactions, backup
      frequently.
      --
      Scott McDaniel
      CS Computer Software
      Visual Basic - Access - Sql Server - ASP
      "Scott Bryce" <sbryce@singlep oint.net> wrote in message
      news:3FF27DC3.4 050103@singlepo int.net...[color=blue]
      > I am creating a CGI application in Perl that uses an Access database. It
      > will be hosted on an NT server. I have used flat file DBMs (tied hashes)
      > on UNIX servers, but I am not familiar with how Access behaves in a
      > multi-user environment.
      >
      > Will I need to use some sort of file locking/semaphore scheme, or does
      > Access (or the ODBC drivers?) manage conflicts between multiple users? I
      > want to avoid corruption of data should multiple users attempt to write
      > to a table/record at the same time.
      >
      > If a semaphore is not normally needed, under what circumstances should I
      > consider using one?
      >[/color]


        Comment

        • Scott Bryce
          #3
          Re: File locking / sempahore necessary in multi user environment?

          Scott McDaniel wrote:[color=blue]
          > Access will handle the file locking internally. The locking scheme is, of
          > course, dependant on how you setup Access/Jet and what parameters you set on
          > your connection objects (ie. adLockPessimist ic, adLockOptimisti c, etc), what
          > type of recordset (if any) you open, etc etc.[/color]

          Not being familiar with Access, I don't know how to set all of that up.
          I suppose you are not familiar enough with the Perl DBI to offer any clues?
          [color=blue]
          > How heavy will the transaction load be?[/color]

          At least several hundred new records every day. Possibly several
          thousand. Probably not as many as 10,000 new records every day. New
          records will be purged periodically and the information will be used to
          generate printable reports. (Or is it better to retain the information
          and flag it as "deleted" in case of data loss requiring the reports to
          be re-generated?)

          [color=blue]
          > If you are going to be doing a LOT of transactions, backup
          > frequently.[/color]

          What is a lot? If the data is purged several times a day, will the
          backups be useful? How often is frequently?



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