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How to reclaim unused space from LOB/CLOB columns?

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  • How to reclaim unused space from LOB/CLOB columns?


    I've been testing how the CLOB columns work (relative to disk space ).

    I've tried erasing data from a couple of columns with CLOB data type (it seems VARCHAR and the other LOBs work in the same way).
    I see there is no change about the size on disk occupied by the table.

    Even if I reorganize the file, the size of file remains.

    If I delete records, and then REORGANIZE, yes, it affects the size on the disk.

    My question is: is there anyway to reclaim space unused on disk by LOB columns in a table? (other option different to deleting records and reorganize teh file).

    Thanks a lot

  • #2
    Can't speak for LOB/CLOB but, if I recall correctly, with VARCHAR it depends on how much space is allocated to the field. So if it is 100 long with an allocated length of 50 then "erasing" the data from the field (i.e. setting the length to zero) will only affect the storage used by those fields that were between 51 and 100 characters in length. The storage occupied by the allocated length will remain even if not actively being used.