Shrinking BLOB tablespace in Oracle 10g

Question

Hello,
I have table created with 32 GB in Oracle 10g with BLOB field containing images. after that I have deleted some of the images from the table but when I'm checking free space, it is show full 32 GB. But when I'm looking at Toad it shows me out of 32 GB 17 GB is free.
my question is how to shrink/resize blob tablespace/table having BLOB field in oracle 10g 2rel ?

Answer 1

Hello urgent,
Tablespace management is not really an Oracle Spatial topic, I suppose these are georaster images?. You probably want to search and post in the more general database forums.
The quick answer is that it is not easy. Oracle tablespaces may only be "shrunk" if the free space is at the end of the datafile at the "high water" mark. If by some wild coincidence the images you removed were indeed at the back of the datafile, then you could alter the datafile with a RESIZE command. But the odds of that being the case are incredibly low. If you really, really MUST recover that space then about the only thing to do is export the data, delete it from the tablespace, shrink the tablespace and then import the data back in. Another approach if you have the space is just move the data into another empty tablespace and then drop the original tablespace. I would guess that the salary expended for you to take everything offline and do this would be more than just buying another cheap disk. Considering that in doing your daily work you may well indeed be in this position again in a few weeks, then it makes even less sense.
Now having said all that I have been in the situation where I MUST recover that space without taking everything offline.
One thing you can try is to "pop" the last items off the datafile (moving them to another tablespace) identified using the query below. But this is an exercise in futility unless your resources happen to be nicely "chunked" together near the highwater mark. Oracle tends to stripe resources across the available space in the datafile. So you might find you need to move half the contents before recovering any significant amount of space.
Cheers,
Paul
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   a.block_id, '
   a.tablespace_name '
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   a.file_id = ( '
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      b.file_name = :p1 '
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