On Wed, Mar 12, 2008 at 9:27 PM, Tom Lane <[EMAIL PROTECTED]> wrote:

>  I didn't like it; it seemed overly complicated (consider dealing with
>  XID wraparound),

We are talking about subtransactions here. I don't think we support
subtransaction wrap-around, do we ?

> and it would have problems with a slow transaction
>  generating a sparse set of subtransaction XIDs.

I agree thats the worst case. But is that common ? Thats what I
was thinking when I proposed the alternate solution. I thought that can
happen only if most of the subtransactions abort, which again I thought
is not a normal case. But frankly I am not sure if my assumption is correct.

> I think getting rid of
>  the linear search will be enough to fix the performance problem.

I wonder if a skewed binary search would help more ? For example,
if we know that the range of xids stored in the array is 1 to 1000 and
if we are searching for a number closer to 1000, we can break the
array into <large,small> parts instead of equal parts and then

Well, may be I making simple things complicated ;-)


Pavan Deolasee
EnterpriseDB http://www.enterprisedb.com

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