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Oracle

Manuals

Just glancing through the 12c manuals (Server Reference 12.1 June 2013 – E17615-16) to check a particular database limit, I came across the following: “Services – maximum per instance – 115″. That’s a bit of a problem, given that you can have 254 pluggable (tenant) databases in a single container database, and each plugged database gets its own service – but I’m guessing that that bit of the manual is wrong, after all it didn’t say anything about pluggable databases at all. It’s hard to keep documentation up to date as things change.

LAOTN Tour (Southern Leg) : ArOUG Day 2…

I was determined to get on a bus tour of Buenos Aires this morning. The plan was to do this yesterday, then spend this morning revisiting a few parts of the city in a bit more detail. Unfortunately, my inability to follow basic directions scuppered that plan… :)

So this morning I got myself to the tour bus and rode the loop of the city, taking photos as I went. You will see lots of blurred images and lots of pictures containing parts of the bus, but I don’t care because they are still good memories. :)

LAOTN Tour (Southern Leg) : ArOUG Day 1…

I arrived in Buenos Aires, Argentina late last night. The ferry ride from Montevideo took about 3 hours.

This morning I got a taxi to the ArOUG conference venue and did my first presentation of the conference. I was originally scheduled to do both my presentations today, then have tomorrow off, but Alex Gorbachev needs to leave earlier tomorrow, so I’ve swapped slots with him and my second presentation is now tomorrow afternoon.

Feeling adventurous, I decided to walk back from the conference venue. The directions seemed pretty straight forward, but I managed to get myself lost. I walked around for quite a while, thinking I must be close to the hotel, but not managing to find it. I eventually decided the only way to get back was to get a taxi. As I walked to find one, I noticed I was standing next to my hotel. Bonus!

LAOTN Tour (Southern Leg) : UYOUG…

The trip from Lima to Montevideo took quite a long time. First I flew back to Santiago, then from there to Montevideo, Uruguay. The drive from the airport to the hotel was pretty cool. It was dark, but we were driving along the coast and the city was all lit up. We arrived quite late, so we dropped off our stuff at the hotel and went out to eat.

12c subquery factoring

I’ve written a few notes about anomalies in subquery factoring (with subquery) in the past, principally making a fuss about the fact that moving an inline view into a “with subquery” can cause a plan to change even when the internal code moves the subquery back in line. With the arrival of 12c one of my first sets of tests was to rerun all the examples to see how many of them had been addressed. I hadn’t written about as many examples as I had thought, and some of them had been fixed before 12c, but here are few references to a couple of outstanding items that I thought worth a mention:

LAOTN Tour (Southern Leg) : Day off in Lima, Peru

I actually got a day off from travelling and presenting yesterday. I would have loved to see Macchu Picchu, but that would take more time than I had available, so instead I went to see Pachacamac, which is about 30 minutes from the city. It is a really big site, about 10 hectares. It must have looked amazing in its heyday. One part of the site is a cemetery, where they estimate there are 40,000 mummies. What with that and the whole human sacrifice thing, it was kind-of freaky. I shall have to get some more information about it and scare my nephews with the story. :)

I took quite a lot of photos, but they don’t really do the site justice.

Bloom Filter

I’ve posted this note as a quick way of passing on an example prompted by a twitter conversation with Timur and Maria about Bloom filters:

The Bloom filter (capital B because it’s named after a person) is not supposed to appear in Oracle plans unless the query is executing in parallel but here’s an example which seems to use a serial Bloom filter.  Running in 11.2.0.3 and 12.1.0.1 (the results shown are the latter – the numbers are slightly different between versions):

Interview with Jonathan Lewis

If you follow my Twitter you probably have heard that Jonathan Lewis visited Moscow in May this year. Thanks to Innova, Jonathan gave a 1-day seminar, and I was one of the lucky people from Russian Oracle community who have been invited to the event.
Even more, I was offered to take an interview with Jonathan which was recorded! It was my first time interview and I was very excited (long before the recording) and scared to death (right in front of the camera) so please forgive me for speaking like a dull. I know that, and it almost doesn’t matter. What matters is Jonathan was brilliant and so excited at times, that 90+ minutes of sitting in a cold room right under air conditioner for me flew like a 1 minute.
Well, enough the words, just enjoy it (this is uncut version recorded in 1 go by the way)!

12c Histogram fixes

I posted a couple of examples some time ago of oddities and boundary cases for frequency histograms on character columns. Part of the process of playing around with the 12c Beta was to re-run such cases to see if newer code made any difference. Looking at these examples, one was fixed (or improved, at least) the other wasn’t, so I’ve added a footnote to each and produced this little note to highlight the changes:

LAOTN Tour (Southern Leg) : PEOUG…

Jonathan Lewis‘ sessions (over WebEx) about “Designing Optimal SQL” and “How to Hint” were extremely popular. The room was full and the audio and slides were very clear. I would say approximately 3/4 of the audience were wearing the simultaneous-translation earphones. Everyone looked very focussed! It was a pity Jonathan couldn’t make it in person, but this was a much better alternative than cancelling his sessions!