Re: Basic LOB Concept

Ken wrote:
> Hi all,
>
> Question regarding the LOB data type. Since, I am also a Java programmer
> and I 've got use to the concept of 2 object references can reference the
> same object instance. I am a bit confused and want to know if this concept
> applies here.
>
> If I INSERT a variable of BLOB type into a row, then it is a POINTER to some
> stored BLOB data area get inserted. If I insert the same variable a second
> time, does it means the same pointer value pointing to the same stored LOB
> data area get inserted - while there is only ONE copy of the LOB data. If
> this is true, that means 2 different rows of the table are refering to the
> same stored LOB data area and modification of one row would implicitly
> modify another row. I dont think that is desirable behaviour of data stored
> in a table.
>
> Could anyone clarify this.
>
> Thx a lot.
>
>

A LOB instance has a locator and a value. The LOB locator is a reference to where the LOB value is physically stored. The LOB value is the data stored in the LOB. Every LOB you insert will have a diffrent locator referencing it!

To add more, you can choose if the LOB is stored inline(in the same tablespace as other rows in the table, or simply put 'inside the same row') or as an 'outline' LOB, where a LOB locator would reference the LOB(and the LOB content is/may stored in a diffrent tablespace). Oracle would automatically store a LOB as an outline LOB, when the size is more than a specific value.

Amogh Received on Wed Jul 13 2005 - 09:53:10 CDT