List:Falcon Storage Engine« Previous MessageNext Message »
From:Jim Starkey Date:January 28 2009 7:49pm
Subject:Re: Problems with record visibility and how it is computed
View as plain text  
Ann W. Harrison wrote:
>
>>
>>> Suppose we had a reusable transaction id as an index into a 
>>> transaction state vector.  That would tie down only a byte per 
>>> transaction rather than a large object.  We would still need a 
>>> mechanism to recycle the transaction ids, however.  Something might 
>>> take a day and think about this...
>>
>> Sounds as big a change as cycle locking.  Let's talk about wait 
>> states with a cycle lock first...
>
>
> I'm not sure that the state vector is that large a change - maybe
> because I've worked with vectors of transaction states before.
>
> It needs to be bigger than a byte - it needs to be the same size
> as the commit id because it has to hold the commit id.  And it
> ought to be a sparse vector - no point in wasting space on
> read-only transactions.  And changing the state of an entry
> has to be done carefully to make the effect atomic. And there
> has to be some way to release the top of the list when nobody
> cares about it any more...
Don't assign the id until the transaction actually does an update.
>
> But it has the advantage of working ... of course making it
> sparse does complicate everything and gets back into locking...
>
>
We could probably make a sparse array that was updated exclusively with 
interlocked CAS -- something to think about when the dog and a fox get 
into a middle of the night bark-fest.


-- 
Jim Starkey
President, NimbusDB, Inc.
978 526-1376

Thread
Problems with record visibility and how it is computedOlav Sandstaa21 Jan
  • search for null values in indexed columnsVladislav Vaintroub21 Jan
    • Re: search for null values in indexed columnsLars-Erik Bjørk21 Jan
    • Re: search for null values in indexed columnsKevin Lewis21 Jan
      • RE: search for null values in indexed columnsVladislav Vaintroub21 Jan
        • Re: search for null values in indexed columnsKevin Lewis21 Jan
      • Re: search for null values in indexed columnsJames Day23 Jan
  • Re: Problems with record visibility and how it is computedOlav Sandstaa23 Jan
    • Re: Problems with record visibility and how it is computedJim Starkey23 Jan
      • Re: Problems with record visibility and how it is computedKevin Lewis28 Jan
        • Re: Problems with record visibility and how it is computedJim Starkey28 Jan
          • Re: Problems with record visibility and how it is computedKevin Lewis28 Jan
            • Cycle Locking (was Problems with record visibility and how it iscomputed)Jim Starkey28 Jan
            • Re: Problems with record visibility and how it is computedAnn W. Harrison28 Jan
              • Re: Problems with record visibility and how it is computedJim Starkey28 Jan
                • Re: Problems with record visibility and how it is computedAnn W. Harrison28 Jan
                  • Re: Problems with record visibility and how it is computedOlav Sandstaa26 Feb
                    • New Transaction State object (Was: Problems with record visibility andhow it is computed)Olav Sandstaa16 Mar
                      • Re: New Transaction State object (Was: Problems with record visibilityand how it is computed)Kevin Lewis16 Mar
                      • Re: New Transaction State object (Was: Problems with record visibilityand how it is computed)Jim Starkey16 Mar
                        • Re: New Transaction State object (Was: Problems with record visibilityand how it is computed)Olav Sandstaa19 Mar
                          • Re: New Transaction State object (Was: Problems with record visibilityand how it is computed)Jim Starkey19 Mar
                            • RE: New Transaction State object (Was: Problems with record visibilityand how it is computed)Vladislav Vaintroub20 Mar
                            • Re: New Transaction State object (Was: Problems with record visibilityand how it is computed)Olav Sandstaa20 Mar
                              • Re: New Transaction State object (Was: Problems with record visibilityand how it is computed)Jim Starkey20 Mar
          • Re: Problems with record visibility and how it is computedOlav Sandstaa28 Jan
            • Re: Problems with record visibility and how it is computedJim Starkey28 Jan
              • Another Idea for Transaction Lifetime ControlJim Starkey28 Jan
                • Re: Another Idea for Transaction Lifetime ControlJim Starkey29 Jan
              • RE: Problems with record visibility and how it is computedXuekun Hu4 Feb
          • Re: Problems with record visibility and how it is computedAnn W. Harrison28 Jan
  • Quick question on row countsKeith Murphy24 Jan
    • Re: Quick question on row countsJim Starkey25 Jan
      • Re: Quick question on row countsKeith Murphy25 Jan