db-derby-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Oystein Grovlen - Sun Norway <Oystein.Grov...@Sun.COM>
Subject Re: Modified UTF-8 or UTF-16 for temporary Clobs?
Date Wed, 23 May 2007 09:32:02 GMT
Mike Matrigali wrote:
  > What is the expected usage pattern for an update on a clob that uses
> these "temporary" clobs?  What is the usual input format, what is the
> usual output format?  Do you expect more than one update usually?  Does
> an update have to rewrite the end of the file on and shrink or expand of
> a middle of the clob?

In client/server, a single update may cause a sequence of updates 
against the embedded driver.  This is because the locator implementation 
  uses a stored procedure to perform the update, and Derby does not 
support Clob as procedure parameters.  To overcome that, the Blob is 
split into segments of max size for VARCHAR.  Hence, it is important at 
the overhead of positioning is not big in these cases.  One way to 
optimize for this would be to remember the end position from last write.

-- 
Øystein

Mime
View raw message