I applied some of the 184.108.40.206 plugin patches to our Cloud Control installation today. We already have Cloud Control 220.127.116.11 installed, so this was just a case of updating the plugins.
Here’s a quick overview of what I did.
- Backup up everything! Database and file system.
- Setup > Extensibility > Self Update
- Download the latest versions of the plugins. The minimum you can really get away with is “Oracle Database (more...)
Because you can never have enough of a good thing.
Here’s a thought – The optimizer doesn’t treat all constants equally. No explanations, just read the code – execution plans at the end:
SQL> drop table t1 purge;
SQL> create table t1 nologging as select * from all_objects;
SQL> create bitmap index t1_b1 on t1(owner);
SQL> alter session set statistics_level = all;
SQL> set serveroutput off
SQL> select count(*) from t1;
SQL> select * from table(dbms_xplan. (more...)
Yesterday, I have seen huge waits “enq SQ – contention’” – in every snapshot there were thousands of waits. But the fix was so simple! Here is the root cause of the issue –
When you select from a sequence, the NEXTVAL generated from a the seq$ table if it is not cached. If it is cached, it will be available in a memory structure and no need to generate the value (more...)
The replicat process is the apply process within the Oracle GoldenGate environment. The replicat is responsible for reading the remote trail files and applying the data found in cronilogical order. This ensures that the data is applied in the same order it was captured.
Until recently there was only one version of a replicat, that version was the classic version. As of 18.104.22.168, there are now three distinct versions of a (more...)
The extract process of Oracle GoldenGate is used to perform change data capture from the source database. The extract can be used to read the online transaction log (in Oracle the online redo logs) or the associated archive logs. The data that is extracted from the source database is then placed into an trail file (another topic for a post) for shipping to the apply sided.
To configure an extract process there needs to (more...)
This is a short post to recommend some recent blog posts by Nikolay Manchev and Bertrand Drouvot on the topic of Oracle Database 12c NUMA awareness.
Nikolay provides a very helpful overview on Linux Control Groups and how they are leveraged by Oracle Database 12c. Bertand Drouvot carried the topic a bit further by leveraging SLOB to assess the impact of NUMA remote memory on a cached Oracle Database workload. Yes, SLOB is very useful (more...)
Having played around with Flashback Data Archive in 11g, I figured I would get through the 12c enhancements pretty quickly. I didn’t account for the fact I’m a donkey and can’t see the wood for the trees. Luckily, I know some people who aren’t stupid and they gave me a nudge in the right direction, allowing me to spot my silly mistake. Thanks Bjoern and Connor!
So after lots of wasted time, here is the (more...)
There’s a thread on the OTN database forum at present asking for advice on optimising a query that’s trying to find “the most recent price” for a transaction given that each transaction is for a stock item on a given date, and each item has a history of prices where each historic price has an effective start date. This means the price for a transaction is the price as at the most recent date prior to (more...)
When I have to run SQL scripts, I prefer to do it via executable ksh scripts (I use ksh because it's usually an Oracle pre-requisite so I can rely on it being installed). One thing that I've just recently started adding into my scripts is exiting sqlplus on error and returning the ORA error code. This is done via the WHENEVER SQLERROR
feature of sqlplus:sqlplus / as sysdba <<EOF whenever sqlerror exit sql. (more...)
I’ve been making some tests recently with the new Oracle 22.214.171.124 In-Memory option and have been faced with an unexpected performance problem. Here is a test case:
create table tst_1 as
with q as (select 1 from dual connect by level <= 100000)
select rownum id, 12345 val, mod(rownum,1000) ref_id from q,q
where rownum <= 200000000;
create table tst_2 as select rownum ref_id, lpad(rownum,10, 'a') name, rownum || 'a' (more...)
Stopping one ASM listener in Flex ASM environment takes down ASM instance
This is a heads-up about behaviour we are seeing during OAT testing on a 12c environment. We are running OAT tests on a new 126.96.36.199 Grid Infrastructure environment using Flex ASM (OEL 5.8) and when taking down one of the two ASMNETLSNR listeners on one of the nodes, the ASM instance running on that node is taken down. We (more...)
There are many different ways of monitoirng Oracle GoldenGate; I have posted about many of these in earlier blog posts. Additionally, I have talked about the different ways of monitoring Oracle GoldenGate at a few conferences as well. (The slides can be found on my slideshare site if wanted). In both my blog and presentations I highlight many different approaches; yet I forgot one that I think is really cool! This one was shown to (more...)
Do you check the alert log of your databases every day? In the morning when you get in? But what about the alerts which happen during the day? How do you spot them – especially if you don’t have Grid Control or Cloud Control configured. Even if you do have a full monitoring solution, this can be useful for a belt-and-braces approach.
Here’s a short bash shell script to use adrci to read through each ORACLE_HOME (more...)
Happy New Year!
Oracle supplied various tools to trace the SQL and identify execution plans for the SQLs. 10046 Event, AUTOTRACE, DBMS.XPLAN etc are some of the most used tracing methods in DBAs daily life. Sometimes, we need to be very careful while using these tools specially using bind variables. Following are some test cases where wrong plans reported by the above tracing tools.
Most easiest method to get (more...)
plus ça change, plus c’est la même chose.
-- Jean-Baptiste Alphonse Karr, Les Guêpes, January 1849 volume
Translation: the more things change, the more they stay the same.
It's been an interesting first year with Io Consulting...uh, I mean Sierra Cedar, Inc. I've had the opportunity to dig deep into the unique Higher Education marketplace, and to help spread the message about Oracle's Cloud Application Services (more...)
To be honest it was asked 2 years ago in a blog about ASM and rebalancing and someone asked the following question
Can I upgrade ASM from 10205 to 11203 while ASM rebalancing is in progress?
and the answer, unsurprisingly, was
Why would anyone even think of asking that question never mind contemplating the idea of running an upgrade under such circumstances.
Needless to say my next blog post is about ASM related activities (more...)
set employer = 'Oracle',
job_title = 'Database Evangelist'
where name = 'Chris Saxon';
That’s right, as of last week I’m now an Oracle employee! I’m joining Steven Feuerstein’s database evangelist team, a hugely exciting opportunity I’m honoured to be a part of. I’ll be joining Natalka, Dan and Todd in helping people customers get the most out of their Oracle databases.
My focus will be SQL and Oracle’s differentiating features (more...)
Now that 188.8.131.52 is certified on RedHat Linux 7 and spin-off environments it’s time to test the installation of RAC on such a system.
The installation of the OS is different from Oracle Linux 5 and 6-with these distributions was very straight forward how to install the operating system the method has changed significantly in release 7. I won’t cover the complete installation here, as always Tim Hall was quicker than me, (more...)
Over the holiday period I finally decided to tackle the Adaptive Query Optimization stuff in Oracle 12c, which resulted in these articles.
Back in Oracle8i the Transportable Tablespace feature was introduced to make it convenient to transport a large amount of data between databases. In Oracle10g this useful feature was enhanced with cross-platform support which allowed a tablespace, or set of tablespaces, to be transported between databases deployed on different hardware platforms (even between platforms with a […]