RE: Ever popular LOB question

Brian,

 

I store them out of line in a separate tablespace.  I have zero evidence
that this is better or worse for the application.  But for a data
management point of view, it made sense to me.  Call it a personal
preference.

 

Sorry if this did not explicitly help you, but it is *free* advice!  And
you know what they say about free advice.

 

Tom

 

________________________________

From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Brian Wisniewski
Sent: Thursday, August 18, 2005 1:28 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: Ever popular LOB question

 

RHAS 3.0/Oracle 9.2.0.6

Is there any benefit to explicitely stating 'out of line' on lobs
outside of rowsize/possible caching issues.  I'm going to be storing
~100K lobs - chunksize defaulted to the blocksize - 8k so obviously
these will be out of line because of their size in this particular
table.  Once the lobs are inserted into the database they will not be
updated.

 

I'm not sure of how Oracle will recognize the entire size of the lob
when it gets it from the application.  Will Oracle start storing it in
line w/ associated redo until it reaches ~4k and then move it out of
line for every one of these lobs?    That would seem like an expensive
operation but I'm not really sure of the behind the sceens actions of
what Oracle is doing.

 

I'm trying to set up some tests with our apps folks but was wondering if
anyone had any insight regarding explicit out-of-line vs in-line
migrated to out-of-line because of size.

 

When we were dealing with smaller lobs we experienced decrease
performance when we had explicitely used out-of-line.  But those lobs at
the time would have been a mix of in-line and out-of-line so I don't
consider that valid given the difference in lob sizes.

 

Test, test, test - I know - just having 'challenges' with developers.  I
also want to test different chunksizes but time is critical right now.

 

Any thoughts/experiences you'd like to share regarding lobs?  

 

Thanks - Brian

 

 

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