OraNA :: Oracle News Aggregator

Having discovered that it’s now easy to create polls, I find that it’s a little addictive.

There have been requests for help going all the way back to 7.3 fairly recently on OTN, so I thought I’d set up a poll to see which versions people had in production. If I’ve got it right you’ll be able to mark multiple choices from the list. 

View This Poll
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Update from Mumbai 2nd Sept 2010: It’s fascinating that two percent of the current vote (9 / 527) goes to 8.0 or earlier.

Some time ago I added the “subscribe” option to the right-hand panel to allow people to register for automatic email whenever I posted a new article. (I’ve also checked how easy it is to unsubscribe if you change your mind  - and it’s very easy) Since then I haven’t been paying attention to how many [...]

From time to time someone will post a question about query performance on the OTN database forum asking why one form of a query returns data almost immediately while another form of the query takes minutes to return the data. Obviously there are all sorts of reasons – the optimizer is not perfect, and different [...]

I was on a customer site recently where I needed to add a NOT NULL constraint to a table of 200 million rows – without taking any downtime. It’s not difficult (provided you are happy with a check constraint rather than a column definition.) alter table t1 add constraint t1_ck_colX_nn check (colX is not null) [...]

Some readers have noticed that a few links to my blog seem to be broken. Don’t panic, it’s not permanent it’s just the result of Don Burleson losing his temper. Let me start by telling you about DMCA, the “Digital Millenium Copyright Act”. DMCA is a mechanism designed to protect Internet service providers (ISPs) from [...]

A couple of years ago I wrote about a poster on the OTN db forum who was puzzled by the fact that when he started rebuilding tables they got bigger.  (Bad luck, sometimes that’s what happens !) A few days ago a related question appeared: I rebuilt some indexes and my query got slower. (Bad [...]

I think anyone who has read Wolfgang Breitling’s material about the optimizer will be familiar with the concept of Cardinality Feedback and one particular detail that when Oracle gets a cardinality estimate of one for a “driving” table then there’s a good chance that the execution plan will go wrong. (That’s not rule, by the [...]

I’ve just been reminded of a thread on OTN which turned into a Q&A about index space usage and various related topics. On re-reading it, I decided it was too good to waste in the backwaters of OTN, so here’s a link to it. Index Space Utilization. Filed under: Indexing, Infrastructure