Rittman Mead - Delivered Intelligence

Today was the official launch of Oracle Database 11g in New York City, whilst another event, the Oracle Fusion IT Conference, was being held at the Emirates Stadium in London. I couldn’t make it to either as I was onsite with a customer, but the New York event marked the public launch of Oracle’s new […]

Certain solitary acts give me great pleasure. Oddly, I consider the intellectual challenge of getting some of my customers’ queries to fly a solitary act, it’s me against the database. Or perhaps me against the customer.
I have been working on a set of poorly performing queries that have been causing a customer a lot of […]

One of the topics I have wanted to research, but have never managed to find time to, is a performance comparison of Oracle OLAP technology and the SQL grouping extensions such as GROUP BY ROLLUP, GROUP BY CUBE and GROUP BY GROUPING SETS. I suppose for that mater I should also include conventional aggregate materialized […]

Today was Day Two of the Miracle DBF up at Edinburgh Castle, and for those of us that got a reasonably early night it was a Nine O’Clock start with Mogens Norgaard on “You Probably Need RAC”. Following on from Mogens was Dan Fink with “No Mogens…” and James Morle with “Brewing Benchmarks”.

After lunch was […]

I’m currently sitting in a pub just down from Edinburgh Castle, in a break between the morning and afternoon sessions. Just across the table from me is Doug Burns, and behind is Thomas Presslie and Carel-Jan Engel, who are working on the Miracle musical for tonight’s gala dinner. We’ve slipped out for a cheeky one […]

A little while back I took part in a partitioning survey. You may have seen it mentioned on Ton Kyte’s blog. It is certainly good to be asked these things - but I expect that the organiser of the survey already had an inkling of my views anyway.
Still, I actually like a lot about Oracle’s […]

Back in January I wrote about a bug we found in the query optimiser that caused some of our complex temporary table star_transformation query candidates to crash the plan evaluation phase of optimisation with an ORA 604 error.
Well, the effort of filing the test case was worthwhile - the guys and gals at Oracle have […]

Yesterday I mentioned a query that would not eliminate unused partitions and resulted in a somewhat large nested loop join plan that would take hours to return. A kind of “find all the rows that match predicate B and then filter the result set on a range of 7 days (out of 800)” type of […]

Constraints do just that; when enforced they constrain data such that rules are obeyed. But even when not enforced the existence of an Oracle RELY constraint does something really useful, it tells the CBO, and especially the query rewrite engine, that certain facts about the data can be presumed to be true. Of course, if […]

Jonathan Lewis posts a nice example (with a subsequent comment from Jeremy expanding it to work well with RAC) of an use of the analytic LEAD function.
Which reminds me of a gotcha with LAG or LEAD with sparse data. Sparse data is commonly found in business intelligence databases at low levels of aggregation. Suppose we […]