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From Kristian Waagan <Kristian.Waa...@Sun.COM>
Subject Re: BLOB question
Date Fri, 03 Oct 2008 09:33:42 GMT
On 09/30/08 16:23, epdv wrote:
> Hello!
> Does BLOB size affect record/database size? I.e., is it a good idea to 
> create a large BLOB for some big and many small images, or should they 
> better be stored in separate tables?


As far as I know, the only thing that will happen is that the page size 
will be set to 32K on table creation when there's a LOB column in the table.

Defining a 2 GB BLOB column, which is the default maximum size, will not 
cause Derby to reserve a huge amount of space. Mixing small and large 
BLOBs in the same table should be fine (although I don't know the 
details regarding space allocation/utilization per page).
You may run into file size limitations imposed by the file system, so 
you should think about how much data you need to store in your table.

If you first insert and then delete lots of BLOBs, compressing the table 
might be a good idea to release free space to the OS.

If you're having performance problems with the BLOBs, please let us know 
and include information about the JDBC methods you use to access the 
BLOBs and which Derby driver you are using.


> Kind regards
> Peter Nabbefeld 

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