Database Software

Folks,

I am seeing some strange behaviour when loading PDF documents into BLOB securefile columns.
Actually, apparently PDFs are **increased** in size when loading into a LOB column.
For other document types (see details below) I can see a compression rate of 2-3 (that what I'd have expected).
Does anyone have any idea what this might be?

Thanks for ideas or comments.

Peter

Here are some details.

I am toying around with Oracle 11.1.0.6.0, and my table looks like this:

CREATE TABLE LOOKUP_TABLE
(
KEY INT NOT NULL ,
DATA BLOB NULL ,
CONSTRAINT XPK_LOOKUP PRIMARY KEY (KEY)
)
LOB(DATA) STORE AS SECUREFILE LOOKUP_LOB (
COMPRESS HIGH
KEEP_DUPLICATES
NOCACHE
FILESYSTEM_LIKE_LOGGING
);

For demos and sample code found on the web I can reproduce the published results.
Also, for many text documents I can see a compression rate of 50%-70%. That seems ok.

Here is the odd thing:
when loading PDF documents the segment size for the LOB segment is actually ***larger*** than the total document size.
For some reason PDF documents seem to create a large overhead and seem to increase in size when loaded into a compressed LOB column.
Actually, for PDFs inside a BASICFILE LOB I am getting better results, i.e. a smaller segment.
Has anyone else seen this? Any idea what this might be?