Uncategorized

Jonathan Lewis's picture

Data Hashing

Here’s a little-known feature that has been around since at least Oracle 10, though I don’t think I had ever seen it in the wild until today when someone reported on the ODC (OTN) database forum that they had a problem getting repeatable results.  It’s always possible, of course, that failure to get repeatable results is the natural consequence of running queries against a multi-user system, but if we assume that this was not the cause in this case we have to ask why a special hashing function that Oracle supplies to allow you to check that a set of data hasn’t changed gives you different results when “the data hasn’t changed”.

connor_mc_d's picture

TO_DOG_YEAR

Some members of the Oracle community got well and truly into the April Fools Day spirit this year.

There were plenty of very earnest looking blog posts about a new 18c function – “TO_DOG_YEAR”.  You can read their posts here

connor_mc_d's picture

New day….new month….New AskTOM

It’s a big day here at AskTOM HQ !

connor_mc_d's picture

Hybrid histograms

Just a quick post here so I could consolidate some information about histograms in 12c.

connor_mc_d's picture

Trip down memory lane

I did a little video for St Patricks day, but it also brought back memories of my first computer experiences.  A Sinclair ZX80, a Commodore 64, and many other machines that I thought were so cool for their time.

Feel free to share your experiences in comments.

connor_mc_d's picture

Text indexes for numbers

We had an AskTOM question recently about being able to search for numbers within a concatenated list. The particular issue was a list of mobile phone numbers, but this is really just about tackling the larger issue of finding numbers within list.

Let’s create a simple example to see where things can break down (and how we can fix them).

Jonathan Lewis's picture

Deferred Invalidation

I was going to write an article on the way 12.2 has introduced the option for “deferred invalidation” for a number of DDL operations, but I did a quick google search before I started writing and found that both Franck Pachot and Richard Foote (yes, rebuild index is one of the operations) had got there long ago, so here are a couple of links – as much for my own benefit as anything else:

Richard Foote:

Franck Pachot:

connor_mc_d's picture

Cool stuff with partition elimination

Sometimes in the IT world, the term “surprise” is not a good one.

“I woke up this morning and got a surprise…my database was down.”

“I ran a SELECT COUNT(*) on my most important table, and got a surprise result of zero rows.”

and so forth. Generally as IT professionals, encountering the unexpected is not a good start to the day Smile.

connor_mc_d's picture

ROWNUM and ORDER BY

Just a quick revisit on an old topic so I could link to this post in a Stack Overflow discussion.

connor_mc_d's picture

Choose your names wisely

It all seems simple enough.  You pick a name for an object…and that is the only object that have than name right ?  For example:

To prevent automated spam submissions leave this field empty.
Syndicate content