On Exadata (or when setting cell_offload_plan_display = always on non-Exadata) you may see the storage() predicate in addition to the usual access() and filter() predicates in an execution plan:
SQL> SELECT * FROM dual WHERE dummy = 'X';
Check the plan:
Display execution plan for last statement for this session from library cache...
SQL_ID dtjs9v7q7zj1g, child number 0
SELECT * FROM dual WHERE dummy = 'X'
Another day, another airport lounge – another quick note: one of the changes that appeared in 12c was a tweak to the “broadcast” distribution option of parallel queries. I mentioned this in a footnote to a longer article a couple of months ago; this note simply expands on that brief comment with an example. We’ll start with a simple two-table hash join – which I’ll first construct and demonstrate in 220.127.116.11:
Recently I’ve been combating a high water mark enqueue wait (enq: HW – contention) on a single node within an Exadata I’m supporting. I first noticed the wait when I was looking at the performance page for the node in Oracle Enterprise Manager 12c. What I noticed was the a lot of brown looking spikes (Image 1). These spikes correspond to a Configuration wait.
When I clicked on Configuration in (more...)
Ever have one of those days when someone calls and says “We/I accidently deleted the whole directory; can you get it back for me”? Well, over the weekend I had that happen with an OEM 12c agent on an Exadata, where the core directory for the agent was deleted by mistake. Before I could evaluate the situation, I had to reassure the end user that the removal of the core directory under the (more...)
Besides been what I consider a horrendous color, “edb360” also stands for Enkitec’s “database 360-degree” view. Simply put: edb360 is a new free tool that provides a 360-degree view of an Oracle database.
What is “edb360“?
This “edb360” tool is the product of a collaborative effort of some very smart guys, and me. Special thanks to Frits Hoogland, Karl Arao, Randy Johnson, Martin Bach, Kyle Hailey, Tanel Poder, (more...)
When adding an Exadata to Oracle Enterprise Manager 12c (OEM), it is pretty easy yet at times you may run into a problem or two. Many of these problems can be minimized by using the Oracle Enterprise Manager 12c: Exadata Discovery Cookbook (cookbook). The cookbook can be found here, so you don’t have to search to far for it.
As with adding any target in OEM, you add the Exadata the same (more...)
Warning: This one may be longer than normal
How many times have you ran an exachk, produced the text file, and then had to either read the file on the compute node or copy it to your local machine? Well there is another way to view the report of the EXACHK; it can even be ran on a timely basis so you have current EXACHK information on a regular basis. What I’m talking (more...)
I’ve previously written about a problem I encountered when kdump is configured to write to an NFS location with UEK (in Exadata software version 18.104.22.168.1). I’m please to report that the root cause of the problem has been identified and there is a very simple workaround.
There were some frustrating times working this particular SR, the most notable being a response that was effectively, “It works for me (and so I’ll (more...)
Deux sessions techniques autour d' Oracle Enterprise Manager sont planifiées prochainement :
- 15 mars : Middleware Management
- 2 avril : Database as a Service
This article looks at the new Oracle Exadata X4-2 Database Machine from Big Red. In part one I looked at the changes made from the X3 model (more stuff) as well as the implications (more license bills). I also covered some of the confusing and bewildering descriptions Oracle has used to describe the flash capacity of the X4. To recap, here are some of the quotes made in various Oracle literature:
Recently I have been asked to investigate the following error on an Exadata system.
ORA-64307: hybrid columnar compression is not supported for tablespaces on this storage type
Well, that’s simple I thought! Must be (d)NFS mounted storage, right? Everyone knows that you can have HCC on Exadata (and a few other storage products). So I looked at the problem and soon found out that the data files in question all resided on the cells. Here (more...)
I seem to be getting a lot of surprising performance results lately on our X-2 quarter rack Exadata system, which is good – the result you don’t expect is the one that teaches you something new.
This time, I was looking at using a temporary tablespace based on flash disks (more...)
I will be delivering a couple of courses soon. One in January and the second in February. I will keep posting upcoming Training and Conferences on a new link at the right margin of this blog.
Exadata Optimizations Jan 13-14
This 2-days “Exadata Optimizations” course is for Developers (more...)
Oracle has released the much-anticipated version of cellsrv compatible with Oracle Database 22.214.171.124 (patch #16980054). Before thinking about upgrading, read MOS note #1571789.1 carefully. Unless you are planning to run database 12c on your Exadata, it would be advisable to continue down the 11.2 branch (more...)
One of the results of my employment history is that I tend to take particular interest in the goings on at a certain enterprise software (and hardware!) company based in Redwood Shores. I love watching Oracle’s announcements, press releases, product releases and financial statements to see what they are (more...)
As I see, the data sheet of Exadata x4-2 says Oracle used 10.000 RPM disks for high performance. You probably know that Exadata provides 2 alternative configurations for hard disks. You may pick high performance (but low capacity) disks, or you may pick high capacity (but low performance) disks. (more...)
Exadata is a different system for a DBA to administer. Some tasks in this environment, such as running the exachk script, require root O/S privileges. This script can be run by the system administrator, and this will be the case if you are managing Exadata as a DBA. However, a (more...)
Today, Oracle announced the Exadata X4-2 model. The X4 has some considerable improvements, namely:
- 12-core Intel Xeon e5-2697 CPUs, up from the 8-core models found in the X3-2 (hello, database licenses!)
- 256GB RAM per database server, upgradeable to 512GB
- 96GB RAM per storage server
- 800GB Sun Flash F80 cards (more...)
A friend of mine asked me last night basically this: “How is that SQLTXPLAIN counts rows?”. In particular, he was referring to the use of the SAMPLE clause of the SELECT statement. Look at this SQLT’s log piece:
SELECT /*+ FULL(t) PARALLEL */ COUNT(*) * 1e4