If Google were to characterise me based on my YouTube views, they would probably list me as some major conspiracy theory junkie. I watch a lot of conspiracy theory rubbish on YouTube, but for me it is light entertainment. I find it amusing to see how they try to present a bunch of random nonsense as science. Watch any of this stuff and you will hear the same types of phrases again and again…
Orignal PDF for this content available here.
A new video webcast, features Gartner research VP, Jim Duggan, and Delphix CEO, Jed Yueh, discussing how IT management should best add business value when data volumes are growing exponentially. Their conversation is an enlightening exploration of a very topical challenge: delivering application projects on time, on budget, and on quality. This at-a-Glance Guide summarizes the 7 essential questions Jim and Jed discuss. For a deeper dive (more...)
Every Oracle database has a data dictionary, which is owned by the SYS user and stored in the SYSTEM tablespace. This consists of read-only tables, which record information about the database e.g. table definitions, details of integrity constraints, usernames and the roles and privileges granted to them etc. You can read about this in detail in Oracle's own documentation.
So, for example, if user SCOTT tries to read a table, Oracle checks the data (more...)
One of the people attending my seminar in Munich last week has emailed me some details about a nasty little surprise you may get if you’re thinking about TSPITR (tablespace point in time recovery), and happen to have a few materialized views in your database.
You might have wanted to use the “duplicate target database” from rman with the “skip tablespace” option to create a duplicate database, excluding tablespaces that you’re not interested in, if you (more...)
In the last article (I hope) of this series I want to look at what happens when I change the parallel distribution method on the query that I’ve been using in my previous demonstrations. This was a query first introduced in a note on Bloom Filters (opens in a separate window) where I show two versions of a four-table parallel hash join, one using using the broadcast distribution mechanism throughout, the other using the hash (more...)
I am slightly disappointed to report that the new extended data types cannot be used in the clustered tables. CLOB columns have never been allowed, and are still not allowed in 12c, but I expected the new data types to pass seamlessly. That is not the case:
SQL> create cluster testclu(intkey number(30,0));
SQL> create index testclu_ind on cluster testclu;
Now, let’s create a normal table (more...)
Just a quick reminder that the second Oracle Midlands event will be taking place on 25th March 2014.
At this event you will get a chance to see Graham Wood (my Dad) speaking about “Advanced ASH Architecture and Usage” and Nikolay Manchev speaking about “Using Clusterware 11g to protect single-instance databases”.
The event is sponsored by those kind folks at Red Gate Software, which means it is not going to cost you anything to (more...)
This is the "really really" final version because it was updated and some additional references added even after the presentation was delivered.
Hoping to do it at Open World 2014 so ... I guess this is the early version of that presentation eh?
You can find it here: Three approaches to shared pool monitoring Hotsos 2014
I polled my session attendee's at Hotsos 2014 ( Three approaches to shared pool monitoring ) and asked them who was using automatic stuff versus who was doing it all manually?
My guess is that there were about 100 people in the room and it looked like automatic "won" but not by much. Maybe 55 percent automatic and 45 manual ... so there are still a whole bunch of people nervous about using that functionality. (more...)
Yesterday I was informed about someone stealing my content again. I take a pretty hard line to this these days. I used to be a little unsure about how to approach it, but now I just hit them with a DMCA take-down notice straight away. I’ve not got time to explain to everyone and their dog about copyright law…
So the current thief has nicked 35+ of my articles. I went to the WordPress.com (more...)
Here is the sqlplus scripting I use to check whether row chaining is degrading a query’s performance:
VARIABLE monitored_sid number;
SELECT sid into :monitored_sid
select b.value "table fetch continued rows"
where b.SID = :monitored_sid
and b.STATISTIC# = (SELECT STATISTIC# FROM V$STATNAME
WHERE NAME='table fetch continued row');
I create a test script with the problem query and put this code after it to (more...)
Random thoughts on a Friday afternoon…
We’ve all got problems. More to the point, every IT department or team has problems of some kind. It’s why we hire consultants, buy products, start long and arduous journeys into the great unknown depths of root cause analysis, and so on.
What fascinates me is the level at which we come to identify with our problems. When I’ve gone into an environment to deliver recommendations, the conversation usually (more...)
Indexes can be very useful tools to improve query performance, but it can be difficult to test indexes in an environment that exactly mirrors production. Although not the preferred method, Oracle offers in 11.2 and later releases the option of invisible indexes. What are invisible indexes? An invisible index can’t be ‘seen’ by any session by default, so it can be created and remain unavailable until testing is scheduled. This can be confusing since (more...)
I received this error message in the following scenario:
– Connect to CDB
SQL> conn / as sysdba
– Start a transaction
SQL> create table test(c number);
insert into test values(1) ;
– Change the container to PDB without completing the transaction
SQL> alter session set container=pdb2;
– Try to shutdown the pluggable database
– It causes ORA-65023 because on switching the container (not making a connection to (more...)
Here’s an oddity that appeared on the OTN database forum last night:
We have this query in our application which works fine in 9i but fails in 11gR2 (on Exadata) giving an “ORA-00937: not a single-group group function” error….
… The subquery is selecting a column and it doesn’t have a group by clause at all. I am not sure how is this even working in 9i. I always thought that on a simple query (more...)
As of today, you can download this free tool out of our Enkitec‘s web page. Just select “eAdam” under the Products Tab.
The next version of eAdam will incorporate the GV$views, equivalent to the currently extracted DBA_HIST set. The reason of this enhancement is to handle read-only databases (DataGuard – DG). So views like GV$ACTIVE_SESSION_HISTORY will be available for data mining within the eAdam staging repository.
Any ways, I hope you enjoy this new (more...)
We had a 8 node RAC cluster that was showing evidence of connections timing out. The following AWR report segments indicates a high level of login activity and blocking on the AUD$ table and segments.
None of it conclusive but what was the kicker was the fact that the aud$ table was still in the system tablespace which is manually managed and therefore automatic segment space management is not coming into play.
Over a 24 (more...)
photo by Jesus Solana
DBAs were cutting edge once upon a time. DBAs protected the company jewels and made sure the company’s data was secure, fast and dependable. DBAs discovered new ways to tune databases, exposed how internals worked, architected and proved optimal database designs. Now that so much information and knowledge has been created , documented, and automated, it seems that DBA work is becoming more and more commoditized. The DBA use to be (more...)
One of the most useful enhancement Oracle has introduced within the release 12c in RMAN is the possibility to execute more SQL statements.
Of course RMAN is primarily used for backup and recovery operations, but sometimes I need to run SQL commands: so in 11g or lower I have to open another terminal/tab or quit the current RMAN session and start a new one with sqlplus.
In Oracle Database 12c instead most of the sql (more...)