LOB's and CHUNK and PCTVERSION

[MikeJones]

Hi all,

I'm a bit lost with the chunck and pctversion parameters of a LOB's storage clause, has anyone out had much experience with them?

Chunk

From what I can gather this is the amount of space oracle will dole out for manipulation of a LOB upto 32K, which as that's the maximum you can manipulate at anyone time would seem fair. So should I set this to 32K as that's only a small bit of memory, if 32 LOB's were being manipulated concurrently (unlikely) it would only consume 1MB of SGA. Or should I set it to a smaller chunk, maybe 8K, which is the size of our DB Blocks, or 16K (2 Blocks), or what??

pctversion

What??? I'm really confussed, my book says that old version of the LOB will not be over written until this percentage of the LOB storage is free, so does that mean that when I commit a LOB it doesn't overwrite the old one always? As i'm really not interested in old versions of the LOB, just the currentlt commited one should I set this to 100?? This seems a little silly to me.


Thanks in advance,

Confused of England

 

[MikeJones]

It's always the last place you look isn't it.

For anyone else that is interested the answer is in your Oracle manual.
Under ADG Large objects (Funnily enough)

chucnk set to DB block size, or bigger if Really big LOBs

pctversion

20% if you have lots or reads and some updates

5% if read but very rarely updated