Yes, I came across this earlier :
Bug 9373758 - Optimization to handle insert of >255 columns (Doc ID 9373758.8)
Salem Ghassan also said that 20901134 was closed as Not a Bug and referred me
back to 9373758.
Hemant K Chitale
From: Kenny Payton [mailto:k3nnyp@xxxxxxxxx]
Sent: Wednesday, May 20, 2015 8:13 PM
To: Chitale, Hemant K
Cc: ORACLE-L
Subject: Re: No Row Chaining "Bug" ?
Not for sure where the 999 comes from but take a look at bug #9373758 and the
following parameter added in 11.2.0.4.4 and 12???? This appears to work for
inserts, although subsequent updates seem to still become multiple row pieces.
"_rowlen_for_chaining_threshold"
I posted the below to this list in Jan.
"
I can’t believe I’ve put this off since April, although not a coincidence that
my company was acquired in May.
I was finally able to test the hidden parameter and it works ( mostly ). I
used imp, trying to keep it simple, to load 100k rows that were plagued with
populated column ID’s > 255. With the parameter set to 0, simulating
pre-parameter, the data loaded with 3,420 chained rows. After setting the
parameter to 8000, with a 8k block size database, I reloaded the data and
although I expected the chained rows to be 0 it left 29. I have yet to explain
the 29 since they are not too large to fit in a block, average row size of 852,
and were less than the 8000 I set the parameter to. After a CTAS of the
previously loaded table the new resulting table with the same 100k rows
returned 0 chained rows. I ran the load process a number of times consistently
with the same results.
Nonetheless, although not perfect it seems to make a significant dent in the
number of inter block chained rows and after some additional testing we will be
excited to get this into production. If I can find some time to dig deeper in
this I’ll try to dump the block and see what is going on.
In case you were wondering, here is the parameter.
_rowlen_for_chaining_threshold
Thanks again Gaja for pointing out the bug ( way back in April )
"
On May 20, 2015, at 4:57 AM, Chitale, Hemant K
<Hemant-K.Chitale@xxxxxx<mailto:Hemant-K.Chitale@xxxxxx>> wrote:
Anyone know what this Bug is :
Bug 20901134 : A ROW WITH 999 COLUMNS WILL NOT CAUSE 'ROW CHAINED' IN 12C
There’s no text in the bug.
Hemant K Chitale
Senior Product Specialist
Finance&Risk Product Engineering
Standard Chartered Bank
7 Changi Business Park Crescent
Singapore 486028
Phone : +65-6596 3127
Email : Hemant-K.Chitale@xxxxxx<mailto:Hemant-K.Chitale@xxxxxx>
Fonenet : 652-63127
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