Re: READ wait events when inserting data into a CLOB
From: Tanel Poder <tanel_at_tanelpoder.com>
Date: Sat, 8 Dec 2012 22:46:10 +0200
Message-ID: <CAMHX9JJGeLVmH42XO=G6t=LsxtNrXymtOn+2yj5zhVY1=919fQ_at_mail.gmail.com>
And that should apply to the write-write contention the same way... (and again it's the LOB-segment specific space management logic which dictates the (different) locations where the two writes physically end up writing). Of course if you try to update let's say only a 1kB portion of a 16kB LOB chunk, then the chunk has to be read from disk first.
Date: Sat, 8 Dec 2012 22:46:10 +0200
Message-ID: <CAMHX9JJGeLVmH42XO=G6t=LsxtNrXymtOn+2yj5zhVY1=919fQ_at_mail.gmail.com>
And that should apply to the write-write contention the same way... (and again it's the LOB-segment specific space management logic which dictates the (different) locations where the two writes physically end up writing). Of course if you try to update let's say only a 1kB portion of a 16kB LOB chunk, then the chunk has to be read from disk first.
On Fri, Dec 7, 2012 at 1:19 PM, Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>wrote:
>
> ----- Original Message -----
> From: "Saibabu Devabhaktuni" <saibabu_d_at_yahoo.com>
>
> | Jonathan,
> | I couldn't reproduce the scenario of reading the same block with "db file
> sequential read" waitevent and immediately followed by "direct path read"
> waitevent.
>
> I thought I did it last night with:
>
> flashback logging on
> lob segment in ASSM tablespace
> switch log file
> flush buffer cache
> insert lob
>
>
-- http://www.freelists.org/webpage/oracle-lReceived on Sat Dec 08 2012 - 21:46:10 CET