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OTN Nordic Tour 2013 – Oslo

We got on the plane from Copenhagen to Oslo and met up with the OUGN folks for some food in the hotel. We spent a long time talking about non-Oracle stuff, like science and religion. It was fun.

The morning started with a long breakfast, which included me nearly throwing orange juice over Mike Dietrich and him succeeding in throwing tea over me. We both blamed the table, but in reality it was our secret desire for a food fight that caused it. :)

Exadata: measuring IO latencies experienced by the cell server

Exadata is about doing IO. I think if there’s one thing people know about Exadata, that’s it. Exadata brings (part of the) processing potentially closer to the storage media, which will be rotating disks for most (Exadata) users, and optionally can be flash.

OTN Nordic Tour 2013 – Copenhagen

I spent the first two sessions of the DOUG event watching Mike Dietrich presenting on 12c upgrades, pluggable databases and new features. I’ve seen some of his stuff already during the LAOTN Tour (Southern Leg), but his presentations have changed a little since I last saw them. To quote Noons,

“Mike’s talk is superb. No bull, just down to facts…”

I think that sums it up nicely. :)

Exadata: what kind of IO requests has a cell been receiving?

When you are administering an Exadata or more Exadata’s, you probably have multiple databases running on different database or “computing” nodes. In order to understand what kind of IO you are doing, you can look inside the statistics of your database, and look in the data dictionary what that instance or instances (in case of RAC) have been doing. When using Exadata there is a near 100% chance you are using either normal redundancy or high redundancy, of which most people know the impact of the “write amplification” of both normal and high redundancy of ASM (the write statistics in the Oracle data dictionary do not reflect the additional writes needed to satisfy normal (#IO times 2) or high (#IO times 3) redundancy). This means there might be difference in IOs between what you measure or think for your database is doing, and actually is done at the storage level.

OTN Nordic Tour 2013 – Stockholm

I didn’t sleep too well the night before the Stockholm event, so I woke up feeling extremely groggy. I think it was just the combination of excitement and adrenalin you get before starting a tour. I met Lonneke and Sten for breakfast, then headed on to the conference venue.

I watched Lonneke presenting on SOA for the first two sessions of the day. This is completely not my area of expertise, but I learnt a lot in these sessions. I now understand a lot of the buzzwords and a lot of the common pitfalls for the first time ever. I’ll never be a SOA guy, but it’s nice to know a little more, so that I can understand when people are leading me astray. You don’t have to know how to swim to recognise when someone is drowning. :)

Exadata and the passthrough or pushback mode

Exadata gets its performance by letting the storage (the exadata storage server) participate in query processing, which means part of the processing is done as close as possible to where the data is stored. The participation of the storage server in query processing means that a storage grid can massively parallel (depending on the amount of storage servers participating) process a smart scan request.

OTN Nordic Tour 2013

I got up this morning in plenty of time to get to the airport to fly to Sweden to begin the OTN Nordic Tour 2013 tomorrow. I then proceeded to wait and wait and wait for the taxi. Eventually it did arrive, but now the rush hour traffic had started to build up, so time was ticking by and we were standing still for a very long time. I tweeted that I would probably miss my flight and I really believed I would.

After a considerable amount of time, with me trying to ignore the nervous glances of my driver, the traffic opened up, I got to the airport and check-in was empty, as was security. I got through in time to grab a drink on the way to boarding. Phew…

Deferrable RI

Here’s a lovely little example that just came up on the OTN database forum of how things break when features collide. It’s a bug (I haven’t looked for the number) that seems to be fixed in 12.1.0.1. All it takes is a deferrable foreign key and an outer join. I’ve changed the table and column names from the original, and limited the deferability to just the foreign key:

EMCLI Rel 3, Post 1

So as the book gets under way on the Enterprise Manager Command Line Interface, (EMCLI) I’m starting to move away from the introduction statements that I commonly was required to repeat to folks, (“it’s the return to the golden age of the DBA 1.0- command line, baby!” :)) and now are onto what has changed in release 3.

Quiz Night

The following output is the result of two immediately consecutive SQL statements (with “set echo on”), and nothing else happening to the database.