Re: LOB Storage

Hi!

On which version you are?

I would create fairly large extents, 64MB for example. LOBs are stored in chunks anyway, extent size doesn't matter that much. One issue is, if you create very large extent size, you might waste some space in LOB index which is a separate, smaller segment (but is always stored with LOB data segment in 9i). But your LOBs will work with 64k extent sizes as well, but that way you might lose some benefit on multiblock direct reads.

Btw, if you use "enable storage in row" then LOB index entries are always stored in row, which means for smaller LOBs which don't fit inline, no LOB index lookup is needed (for large ones I believe there still is, because large LOBs can't be addressed with small inline inode structure).

If your average lob size is in megabytes, I'd put them into 16k or 32k tablespaces, away from regular block size and create a different buffer pool for them - if you are using "CACHE" type lobs. That way they won't affect LRU mechanisms for "normal" data buffers.

Tanel.

• Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Tuesday, September 30, 2003 11:24 PM

> All,
>
> I'm being given a requirement to store a BLOB column in the database. I'm
> being told that the average size of the file (it's a PDF) is 12,000 K.
I'm
> assuming that I should store this column in a separate tablespace from the
> table data. If I use an LMT tablespace, what should I use for the uniform
> allocation size? Should I use 12,000 K or something larger to store one
PDF
> per segment? Am I all wrong here?
>
> thanks in advance
>
> Tom Mercadante
> Oracle Certified Professional
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> Author: Mercadante, Thomas F
> INET: NDATFM_at_labor.state.ny.us
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-- 
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Author: Tanel Poder
  INET: tanel.poder.003_at_mail.ee

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