Skip to main content

A few thoughts about OCM 12c upgrade

Yesterday I sat for the 12c OCM upgrade exam, which I mentioned in few blog posts before. The first step after checking your ID is of course signing the NDA, and thus you won't find much real information here.

This time I chose Utrecht as the place to take the exam. Not that I have any special preference, I took each of the exams in a different place so far. The only requirements were convenient time and location defined as 'somewhere in Europe'. But in the end, Utrecht turned out to be a good place. Oracle NL headquarters are easy accessible, it's a very new building, the lunch was good:-)
And the city is nice to see.

Regarding the exam, the usual important notes still hold true:

  1. Arrive on time. It's a long day and you will have a lot of things to do.
  2. You will work hard the whole day. Get a good sleep before, be well rested.
  3. Review the exam topics well. Note that they may have change over time. There is for example an update as of January 1, 2016: Flex ASM was added.
  4. Learn how to work with the docs - with no search available. You will need the docs, nobody can remember all the syntax and all the arcane settings.
  5. Love your command line. "GUI is not available for every segment of the exam." And anyway, it's much faster to do things in sqlplus. And you will struggle for time.
Now I just have to wait for the results... And for any of you who wants to take the exam: Good luck!

Comments

Vasily said…
Hi! Did you pass?
Vit Spinka said…
Yes, I was actually lucky enough to pass the exam.

Popular posts from this blog

Filter and access predicates

More than just column projections When we look around for further pointers in the tree nodes, we find more pieces resembling the column projections we have seen so far. With some experimenting, we will find out that these are access predicates and filters. First of all, the location of these pointers is not always the same, it seems that the value at 0x34 is some kind of flag, indicating whether filters and/or access predicates are present, and where. Or whether there is just one, or more of them.  It probably also indicates what other info is present, but I have no idea what info that would be or what each value means. Resembling, but different The data we see as predicates are not columns; after all, a predicate is a condition, not a single column. But the structure is similar to what we have seen with columns, and if we follow pointers further, we eventually build a tree, and some of the leaves are indeed just column projections. After some contemplation, we realize it's...

dbms_alert on RAC

Not long time ago, I came across a usage of dbms_alert to manage running jobs. As the solution implemented must work also for RAC, I wanted to know whether dbms_alert works on RAC across instances. The documentation nor Metalink does not say anything (contrary to dbms_pipe, which does NOT work on RAC). So, if they don't warn, it should work... However, Julian Dyke says, that dbms_alert does not work and is the same as dbms_pipe (sources: http://juliandyke.com/Presentations/Presentations.html#ARoughGuideToRAC , page 17, or Pro Oracle Database 10g RAC on Linux, page 426). You know, never trust anybody, so I conducted a test case (10.2.0.3 on Linux x86_64, VMware ESX server, 2-node RAC): You will need two simultaneous sessions, I mark them with DWH1> and DWH2> here. DWH1> select instance_name from v$instance; INSTANCE_NAME ---------------- DWH1 DWH2> select instance_name from v$instance; INSTANCE_NAME ---------------- DWH2 DWH2> exec dbms_alert.register('TST'); ...

Execution plan rows

The plan As mentioned in previous post, our example is based on the sample SH schema, with an added table FOOBAR (id number, key varchar2(30)): SELECT prod_id, key FROM products CROSS JOIN foobar WHERE prod_id in (143,144,id) and id in (1,2,3); In all reverse engineering, it's good to start with something simple and to know what we to look for. Thus we want to know what the execution plan should look like; and the more unique numbers/ids we can find, the better. It's much easier to look for a number like 0x12fa1893 than for 0x0 or 0x1. The execution plan, obtained using: SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY(null,null,'ALL'));  is I have added the CPU cost from the full detail of the execution plan in  v$sql_plan / x$kqlfxpl. Looking at the numbers, we also have rows (1 and 2 ... not very unique), bytes (34 / 30 / 8 - not bad) and what is not shown here, we also know object ids of the index and the table: 94765 and 92749 (nice). We did not use any...