Non-technical

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UKOUG Tech 18

One month to go before the big event in Liverpool. so I’ve been browsing the agenda to get some idea of the talks I’ll probably go to. At present this is what my list looksl like:

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Soup

When my mother-in-law comes round to Sunday lunch we often have roast chicken – and a serious error in estimating the requirement for the vegetable bed I was roasting on led to the discovery of home-made soup. (I did warn you that my post-operative posts would be light-weight)

Ingredients

  • Remnants of cooked chicken
    • (or 250ml, 1/3rd pint, one cup of  boiled water with a vegetable or chicken stock cube)
  • One large carrot
  • One small parsnip
  • One medium onion
    • The three vegetables should be similar in weight: roughly 200g, a bit less than 1/2 lb.
    • (Or just about any leftover vegetables from a roast dinner – I’ve even used leeks in cheese sauce)
  • Greek yoghurt (One tablespoon)
  • Choice of herbs and seasoning.

 

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Eye, Eye, Cap’n

By the time you read this I will have had the lenses in both my eyes replaced, so I won’t be staring at a computer screen for a while – and that means, in particular, I won’t be doing any further investigation into join cardinality for a while.

For those who might otherwise feel deprived of my exquisite prose I have, however, prepared a couple of lightweight articles for automatic launching over the next few days. But please don’t expect any prompt follow-ups if you add comments or send email over the next couple of weeks.

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RTFM ?

My entrance at the Polish Oracle User Group conference 2017 has just resurfaced on Twitter. There is a back-story to this which contains an allegorical lesson in using Oracle. As I said in the opening remarks in the subsequent presentation: “The lesson began before I got to the stage”.

Like all the other speakers at POUG2017 I had received an email asking me to name a tune for a playlist. Having decided that Beethoven, Brahms and Tchaikowski were not the sort of composers the organisers had in mind I nominated (with a touch of irony) “Who wants to live forever?” by Queen (despite Richard Foote’s strenuous efforts to turn the Oracle world to David Bowie).

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Been There

It’s the end of the year and time for a retrospective of some sort so I was thinking of listing the top 10 most popular pages on my blog, but Connor McDonald beat me to it, so I decided to see if I could remember all the countries I’d visited since starting to work with the Oracle software, and here’s the list in alphabetical order:

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#ThanksOTN

To mark the OTN Appreciation Day I’d like to offer this thought:

“Our favourite feature is execution plans … execution plans and rowsource execution statistics … rowsource execution statistics and execution plans …  our two favourite features and rowsource execution stats and execution plans … and ruthless use of SQL monitoring …. Our three favourite features are rowsource execution stats, execution plans, ruthless use of SQL monitoring and an almost fanatical devotion to the Cost Based Optimizer …. Our four … no … amongst our favourite features  are such elements as rowsource execution statistics, execution plans …. I’ll come in again.”

With apologies to Monty Python.

 

 

 

Jonathan Lewis's picture

Month End

A question about parallel query and cardinality estimates appeared on OTN a little while ago that prompted me to write this note about helping the optimizer do the best job with the least effort.  (A critical point in the correct answer to the original question is that parallel query may lead to “unexpected” dynamic sampling, which can make a huge difference to the choice of execution plans, but that’s another matter.)

The initial cardinality error in the plan came from the following predicate on a “Date dimension” table:

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Centenary

I rarely blog about anything non-technical but after the events last Friday (1st July) I wanted to say something about the pride that I shared with several hundred parents around the country as they saw the effect their offspring created through a living memorial of the terrible waste of life that happened  a hundred years ago on 1st July 1916 when some 70,000 soldiers (a very large fraction of them British) were killed or injured on the first day of the battle of the Somme.

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Speaker Scores

I published a note this morning that I drafted in January 2015, and I didn’t notice that it had gone back in time to publish itself on the date that I first drafted it – and it’s already been tweeted twice so I can’t move it. So this is a temporary link to pop it to the head of the queue while leaving it where it first appeared.

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Learning

I received an email a few weeks ago asking me if I would look at a series of three posts on adaptive dynamic sampling in 12c – (part 1, part 2, part 3). I took a note of the topic and URLs, and read through them fairly rapidly, and they seemed to be perfectly reasonable articles describing the authors thoughts, tests, and observations.

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