Blog Aggregator - Amardeep Sidhu

In the UK - in March.  See this link for details.  I know the instructor Carel-Jan Engel and he not only presents very well, he knows his stuff - especially regarding data guard.

So, if you want to be taught data guard by someone who uses it a lot and are near to the UK - this class is for you.

I love reading The New Yorker magazine. Partly the it is sheer expanse of the articles, which are measured in pages rather than paragraphs. But also it’s the breadth of the coverage. Okay, so I could do without the profiles of baseball coaches but pretty much every article is worth reading. Unfortunately I lack the time to read each issue, so these days I buy it when I want to pretend I am still a leisured (and cultured) person.

I have just got around to reading last week’s issue. It contained a fascinating piece by Atul Gawande on the use of checklists in intensive care units. ICU staff deal with an very complicated piece of machinery (i.e. us) when it’s in an extremely precarious state (hence the need for intensive care). There are thousands of different ICU procedures. Each procedure consists of multiple steps; if somebody misses or botches a step there are often terminal consequences for the patient. Furthermore each condition requires a unique combination of ICU procedures, staff and equipment. Patients in intensive care frequently die there.

In his piece Gawande talks about the efforts of a critical-care specialist named Peter Pronovost to improve survival rates by the simple expedient of checklists for a handful of common yet critical procedures. It is astonishing how such a simple thing can make such a profound difference:

“Pronovost and his colleagues monitored what happened for a year afterward. The results were so dramatic that they weren’t sure whether to believe them: the ten-day line-infection rate went from eleven per cent to zero. So they followed patients for fifteen more months. Only two line infections occurred during the entire period. They calculated that, in this one hospital, the checklist had prevented forty-three infections and eight deaths, and saved two million dollars in costs.”

Less surprising but more depressing is the difficulty Pronovost experienced in persuading highly-qualified doctors to bother themselves with yet more form-filling.

Most of us in IT have similarly mundane-yet-complicated procedures. Of course, hardly any of our procedures are literally life-or-death, but there are usually penalties for getting them wrong (even if it’s only digging out the manuals to refresh our memories on Flashback Database). Checklists are good because they prompt us to go through each step of a prccedure. And because the machinery we deal with is a lot more tractable than the human body we can often automate our checklists into stored procedures, shell scripts or workflow processes.

Gawande’s article reminded me of a couple of things I do on an infrequent but regular basis which would benefit from being documented in a checklist. But it’s also a fine and moving piece of writing and worth reading in its own right.

A colleague asked me whether NOT IN would return the same as MINUS. I said it would depend on whether the results contained nulls. I confess to not being clear as to how the results would be affected by the presence of nulls, but it’s easy enough to knock up a test case.

We start with both tables containing nulls:

SQL> select id from a10
2 /
ID
———-
1

1 row selected.

With a null in the top table but not in the bottom table:

SQL> delete from a20 where id is null
2 /

SQL>

With a null in the bottom table but not in the top table:

SQL>

With no nulls in either table:

SQL> delete from a20 where id is null
2 /

SQL>