Re: clustering without locking

On Fri, May 2, 2008 at 9:12 AM, fschmidt <fschmidt@[EMAIL PROTECTED]
> wrote:
>
>  An implementation of clustering without locking would start by
comparing the
>  index to the table from the beginning to find the first mismatch.  Rows
>  before the mismatch are fine, and can be left alone.  From here on, go
>  through the index and rewrite each row in order.  This will put the
rows at
>  the end of the table in cluster order.  When done, vacuum the table. 
This
>  will result in a clustered table without any locking needed.  Those few
>  records that were updated while clustering was happening will be out of
>  order, but that should only be a few.

In your proposal, a large amount of dead tuple can be generated in both
table and index. This is a serious problem that spoils the effect of
clustering.

-- 
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE COR****ATION
NTT Open Source Software Center

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