Rollback usage query

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  • Alice
    #1

    Rollback usage query

    Hi all,

    Given a rollback segment with storage as follows :
    Initial Extent 5 MB
    Next Extent 5 MB
    Min Extents 20

    Does this mean that every time a transaction uses this rollback segment it
    allocates 100 MB ?
    Does this mean that if there are two transactions using this rollback
    segment, 200 MB is required ?

    Thanks,
    Alice


    Tags: None
    • Matt
      #2
      Re: Rollback usage query

      No. A transaction will only use as much space as it requires.

      The rollback segment tablespace is just like any other tablespace (as
      far as storage is concerned). Therefore it will allocate storage in
      multiples of database blocks (db_block_size) .

      A rollback segment that has 20 extents of 5Mb each has 100Mb available
      for use by any number of transactions concurrently.

      Matt



      "Alice" <alice@reply-to-group.com> wrote in message news:<40742a46_ 1@news.tm.net.m y>...[color=blue]
      > Hi all,
      >
      > Given a rollback segment with storage as follows :
      > Initial Extent 5 MB
      > Next Extent 5 MB
      > Min Extents 20
      >
      > Does this mean that every time a transaction uses this rollback segment it
      > allocates 100 MB ?
      > Does this mean that if there are two transactions using this rollback
      > segment, 200 MB is required ?
      >
      > Thanks,
      > Alice[/color]

        Comment

        • Alice
          #3
          Re: Rollback usage query

          Thank Matt.

          Regards,
          Alice

          "Matt" <mccmx@hotmail. com> wrote in message
          news:cfee5bcf.0 404080123.64767 013@posting.goo gle.com...[color=blue]
          > No. A transaction will only use as much space as it requires.
          >
          > The rollback segment tablespace is just like any other tablespace (as
          > far as storage is concerned). Therefore it will allocate storage in
          > multiples of database blocks (db_block_size) .
          >
          > A rollback segment that has 20 extents of 5Mb each has 100Mb available
          > for use by any number of transactions concurrently.
          >
          > Matt
          >
          >
          >
          > "Alice" <alice@reply-to-group.com> wrote in message[/color]
          news:<40742a46_ 1@news.tm.net.m y>...[color=blue][color=green]
          > > Hi all,
          > >
          > > Given a rollback segment with storage as follows :
          > > Initial Extent 5 MB
          > > Next Extent 5 MB
          > > Min Extents 20
          > >
          > > Does this mean that every time a transaction uses this rollback segment[/color][/color]
          it[color=blue][color=green]
          > > allocates 100 MB ?
          > > Does this mean that if there are two transactions using this rollback
          > > segment, 200 MB is required ?
          > >
          > > Thanks,
          > > Alice[/color][/color]


            Comment

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