Re: blobs <-> diskspace
In article <3308551C.66F5EA39@imagine.lec.dk>, =?iso-8859-1?q?S=F8ren_=C
6rendahl_Mikkelsen?= <sam@imagine.lec.dk> writes
>I have a question regarding blob's.
>
>If I have a table like below
>
>CREATE TABLE test
>(
> num_1 INTEGER NOT NULL,
> doc_1 TEXT,
> doc_2 TEXT IN blob_dbs,
> ) IN data_dbs;>
>and inserts a number into num_1 and let doc_1 and doc_2 be empty.
>
>Do doc_1 and doc_2 occupy any space when left empty (e.g. a page or a
>zero length indication) ?
>Please notice the difference between doc_1 and doc_2 before answering.
>
>Thanks,
Yes they are both a 56-byte descriptor to where the blob is really
stored, either in blob pages within a dbspace (doc_1) or within a
blobspace (doc_2):- OnLine Admin Guide 7.1 Volume 2 Page 43-59 :-
"Data rows that include blob data do not include the blob data in the
row itself. Instead, the data row contains a 56-byte blob descriptor
that includes a forward pointer (rowid) to the location where the
first segment of blob data is stored. The descriptor can point to a
blob page (if the blob is stored in a dbspace), a blobpage (if the
blob is stored in a blobspace), or to an optical platter (if you
are using OnLine/Optical)."
The above quote is Copyrighted by Informix, so go away Oracle!
--
David Williams