Oracle

Jonathan Lewis's picture

Truncate – 2

Following on from my earlier comments about how a truncate works in Oracle, the second oldest question about truncate (and other DDL) appeared on the OTN database forum“Why isn’t a commit required for DDL?”

Sometimes the answer to “Why” is simply “that’s just the way it is” – and that’s what it is in this case, I think.  There may have been some historic reason why Oracle Corp. implemented DDL the way they did (commit any existing transaction the session is running, then auto-commit when complete), but once the code has been around for a few years – and accumulated lots of variations – it can be very difficult to change a historic decision, no matter how silly it may now seem.

oraclebase's picture

Fedora 22/23 and Oracle 11gR2/12cR1

linux-tuxAs always, installations of Oracle server products on Fedora are not a great idea, as explained here.

I was reading some stuff about the Fedora 23 Alpha and realised Fedora 22 had passed me by. Not sure how I missed that. :)

Anyway, I did a run through of the usual play stuff.

oraclebase's picture

Oracle Midlands : Event #11

Just a quick note to say Oracle Midlands Event #11 is nearly here.

om11

Cheers

Tim…


Oracle Midlands : Event #11 was first posted on August 25, 2015 at 2:36 pm.
©2012 "The ORACLE-BASE Blog". Use of this feed is for personal non-commercial use only. If you are not reading this article in your feed reader, then the site is guilty of copyright infringement.
Jonathan Lewis's picture

Truncate

The old question about truncate and undo (“does a truncate generate undo or not”) appeared on the OTN database forum over the week-end, and then devolved into “what really happens on a truncate”, and then carried on.

The quick answer to the traditional question is essentially this: the actual truncate activity typically generates very little undo (and redo) compared to a full delete of all the data because all it does is tidy up any space management blocks and update the data dictionary; the undo and redo generated is only about the metadata, not about the data itself.

Jonathan Lewis's picture

Oops

I made a mistake a few days ago following up a question on the OTN database forum. The question was about a problem creating a hash/list composite partitioned table, and one of the respondants suggested that perhaps the problem appeared because hash/list wasn’t a legal combination.

Spot on: so I confirmed that observation and supplied a link to the official Oracle white paper that listed the combinations that were legal in 11.2 for composite partitioning.  In fact, although I was fairly sure that hash/list wasn’t legal, I had even run up a quick test to check that the attempt would fail before I’d searched online for the document.

dbakevlar's picture

The Evolution of a Programmer and the Pythonic Way of Thinking

There’s an old joke about the evolution of a programmer. It starts with the programmer in their infancy and typing:

Print “Hello World” and so the output returns:

dbakevlar's picture

Emulating a Raspberry Pi on Virtualbox

So I’m working on a lot of posts for Enterprise Manager, but I can’t post them just yet, so here’s some more Raspberry Pi love to keep you busy until then… :)

Jonathan Lewis's picture

Index Usage

The question of how to identify indexes that could be dropped re-appeared (yet again) on the OTN database forum last week. It’s not really surprising that it recurs so regularly – the problem isn’t an easy one to solve but new (and even less new) users keep hoping that there’s a quick and easy solution.

There are, however, strategies and pointers that can help you to optimise the trade-off between effort, risk, and reward. Broadly the idea is to spend a small amount of effort finding a relatively small number of “expensive” indexes that might be safe to drop, so that when you do the detailed analysis you have a good chance that the time spent will be rewarded by a positive result.

Before we get to some results posted on OTN, it’s worth thinking about the global impact and what we’re trying to achieve, and the threats that go with our attempt to achieve it.

oraclebase's picture

VirtualBox 5.0.2

VirtualBox 5.0.2 has been released. It’s the first maintenance release for the 5.0 version.

Downloads and changelog in the usual places.

Cheers

Tim…


VirtualBox 5.0.2 was first posted on August 14, 2015 at 6:29 pm.
©2012 "The ORACLE-BASE Blog". Use of this feed is for personal non-commercial use only. If you are not reading this article in your feed reader, then the site is guilty of copyright infringement.
oraclebase's picture

OTN Tour of Latin America 2015 : PEOUG, Peru – Day 1

A quick taxi ride got us to the conference hotel really quickly, so we were nice and early for the PEOUG event.

After the introductions by Miguel Palacios, it was time for the first sessions of the event. Of the English speakers, first up were Debra Lilley and Dana Singleterry. Debra had some problems with her laptop, so she did her presentation using mine and all went well. Dana did his session over the net, so I sent a few Tweets to let him know how things looked and sounded from our end. I figured a bit of feedback would help reassure him there weren’t any technical issues.

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