Straight after the Oracle University Expert Summit in Berlin – which was a big success, by the way – the circus moved on to another amazing place: Istanbul!
The Turkish Oracle User Group (TROUG) did its annual conference in the rooms of the Istanbul Technical University with local and international speakers and a quite attracting agenda.
Do you recognize anyone here?🙂
I delivered my presentation “Best of RMAN” again like at the DOAG annual conference last year:
Many thanks to the organizers for making this event possible and for inviting us speakers to dinner
The conference was well received and in my view, it should be possible to attract even more attendees in the coming years by continuing to invite high-profile international speakers
My special thanks to Joze, Yves and Osama for giving me your good company during the conference – even if that company was sometimes very tight during the car rides😉
I really enjoy working for Oracle University as an instructor – especially when being able to contribute to events like this🙂
Today, I got this message in my alert.log file:
Full DB Caching disabled: DEFAULT_CACHE_SIZE should be at least 709 MBs bigger than current size.
When I look at the datafile sizes and compare them with the buffer cache size, it shows:
SYS@cloudcdb > select name,bytes/1024/1024 as mb from v$sgainfo; NAME MB -------------------------------------------------- ---------- Fixed SGA Size 2,80265045 Redo Buffers 13,1953125 Buffer Cache Size 3296 In-Memory Area Size 2048 Shared Pool Size 736 Large Pool Size 32 Java Pool Size 16 Streams Pool Size 0 Shared IO Pool Size 208 Data Transfer Cache Size 0 Granule Size 16 Maximum SGA Size 6144 Startup overhead in Shared Pool 181,258133 Free SGA Memory Available 0 14 rows selected. SYS@cloudcdb > select sum(bytes)/1024/1024 as mb from v$datafile; MB ---------- 3675
It is true, the database doesn’t fit completely into the buffer cache, missing roughly that amount of space mentioned. There is no such parameter as DEFAULT_CACHE_SIZE, though.
What we have instead is DB_CACHE_SIZE. In order to fix that issue, I was using this initialization parameter file to create a new spfile from:
[oracle@uhesse-service2 dbs]$ cat initCLOUDCDB.ora *.audit_file_dest='/u02/app/oracle/admin/CLOUDCDB/adump' *.audit_trail='db' *.compatible='126.96.36.199.0' *.control_files='/u02/app/oracle/oradata/CLOUDCDB/control01.ctl','/u03/app/oracle/fra/CLOUDCDB/control02.ctl' *.db_block_size=8192 *.db_domain='' *.db_name='CLOUDCDB' *.db_recovery_file_dest='/u03/app/oracle/fra' *.db_recovery_file_dest_size=10737418240 *.diagnostic_dest='/u02/app/oracle' *.dispatchers='(PROTOCOL=TCP) (SERVICE=CLOUDCDBXDB)' *.enable_pluggable_database=true *.open_cursors=300 *.processes=300 *.remote_login_passwordfile='EXCLUSIVE' *.undo_tablespace='UNDOTBS1' *.sga_target=6g *.pga_aggregate_target=2g *.inmemory_size=1g *.db_cache_size=4g
That reduced the size of the In-Memory Column Store to make room for the buffer cache. Now the database fits nicely into the buffer cache again:
SYS@cloudcdb > select name,bytes/1024/1024 as mb from v$sgainfo; NAME MB -------------------------------------------------- ---------- Fixed SGA Size 2,80265045 Redo Buffers 13,1953125 Buffer Cache Size 4256 In-Memory Area Size 1024 Shared Pool Size 800 Large Pool Size 32 Java Pool Size 16 Streams Pool Size 0 Shared IO Pool Size 0 Data Transfer Cache Size 0 Granule Size 16 Maximum SGA Size 6144 Startup overhead in Shared Pool 181,290176 Free SGA Memory Available 0 14 rows selected.
Accordingly the message in the alert.log now reads
Buffer Cache Full DB Caching mode changing from FULL CACHING DISABLED to FULL CACHING ENABLED
Don’t get me wrong: I’m not arguing here against the In-Memory Option or in favor of Full Database Caching. Or whether it makes sense to use any of them or both. This post is just about clarifying the strange message in the alert.log that may confuse people.
And by the way, my demo database is running in the Oracle Cloud🙂
Join us in Berlin, 18th – 20th April. The event will take place at the Adlon Hotel with Jonathan Lewis, Pete Finnigan, Christian Antognini, Javier de la Torre Medina and myself as speakers. We have over 70 enrollments already, so take action to secure your seat in time!
My topic will be Rolling Upgrade from 11g to 12c, with a special focus on doing it with Transient Logical Standby. In a live demonstration I will start with a Primary and a Physical Standby Database both running 188.8.131.52 in Maximum Availability protection mode using the Data Guard Broker. This is likely one of the most common setups today. We will then see how to upgrade this configuration to 184.108.40.206 with minimum downtime.
When I did this seminar before during another Expert Summit in Dubai, I was still using 220.127.116.11 as the initial release, then upgrading it to 18.104.22.168. It took me some time and effort to update my demo environment and the lessons to cover more recent and meanwhile more relevant versions. Hope to see you there🙂