Oracle

Jonathan Lewis's picture

Reverse Key

A question came up on the OTN database forum recently asking if you could have a partitioned index on a non-partitioned table.

(Aside: I’m not sure whether it would be quicker to read the manuals or try the experiment – either would probably be quicker than posing the question to the forum. As so often happens in these RTFM questions the OP didn’t bother to acknowledge any of the responses)

marco's picture

A Database Wordfile…

It is not often that something like the following happens on Google while searching for…

oraclebase's picture

Feedback from the Oracle documentation team

feedbackI got some feedback from the Oracle documentation team, based on my recent post.

GUIDs

One of the concerns I raised was about how the GUIDs would be used in different releases of the documentation. Although I don’t like the look of the GUIDs, I can understand why they might be more convenient that trying to think of a neat, descriptive, human readable slug. My concern was the GUID might be unique for every incarnation of the same page. That is, a new GUID for the same page for each patchset, DB version and/or minor text correction. That would make it really hard to flick between versions, as you couldn’t predict what the page was called in each variant.

oraclebase's picture

Oracle Enterprise Manager Cloud Control 12c Release 5 (12.1.0.5) – Just Born

em-12cOracle Enterprise Manager Cloud Control 12c Release 5 (12.1.0.5) was announced a few days ago. I woke up today and checked the interwebs and it’s actually available for download.

I must admit I’m a little nervous about the upgrade. I had a few bad times with upgrades in the early days of Grid Control and Cloud Control and that has left me with a little bit of voodoo lurking in the back of my mind. The last couple of upgrades have been really easy, so I’m sure it will be fine, but that voodoo…

I’ll download it now and do a clean install. Then do a couple of practice upgrades. If all that goes well, I’ll schedule a date to sacrifice a chicken, raise a zombie from the dead to do my bidding, then do the real upgrade.

Jonathan Lewis's picture

Dynamic Sampling

Following on from an OTN posting about dynamic sampling difficulties I had planned to write a blog post about the difference between “not sampling when hinted” and “ignoring the sample” – but Mohamed Houri got there before me.

It’s just worth highlighing a little detail that is often overlooked, though: there are two versions of the dynamic_sampling() hint, the cursor level and the table level, and the number of blocks sampled at a particular level is dependent on which version you are using.  Level 4 at the cursor level, for example, will sample 64 blocks if and only if a certain condition is met,  but at the table level it will sample 256 blocks unconditionally.

Jonathan Lewis's picture

CBO Series

About a year ago I came across a couple of useful articles from Stefan Koehler, which is when I added his name to my blog roll. As an introduction for other readers I’ve compiled an index for a series of articles he wrote about the CBO viewed, largely, from the perspective of using Oracle to run SAP. Today I realised I hadn’t got around to publishing it, and there’s been a couple of additions since I first started to compile the list.

pete.sharman's picture

EM 12.1.0.5 has been announced!

The latest version of Enterprise Manager, EM 12.1.0.5, has been announced! The announcement can be seen here. Obviously, there will be a number of posts that come out about it over the next few weeks, so I’ll add this post here as a quick notification and will update it with links to more information as it becomes available.

Technical Articles

Managing the Hybrid Cloud with Oracle Enterprise Manager – Demo
A First Technical Look At Hybrid Cloning in EM12c Release 5

oraclebase's picture

Oracle Documentation URLs : What I would like to see!

Broken-LinkAfter my recent rant about broken URLs, I thought it would be sensible to say something a little more constructive, so this is what I would do if I were asked to structure the documentation. Other opinions are valid. :)

Base URL: I’m assuming the base URL for the database documentation will never change again from it’s current value.

Jonathan Lewis's picture

Predicate Order

A recent OTN post demonstrated a very important point about looking at execution plans – especially when you don’t use the right data types. The question was:

We’ve this query which throws invalid number

SELECT * FROM table A
WHERE A.corporate_id IN (59375,54387) AND TRUNC(created_dt) BETWEEN '19-DEC-14' AND '25-DEC-14';

However it works fine if we use not in instead of in

SELECT * FROM table A  
WHERE A.corporate_id  NOT IN (59375,54387) AND TRUNC(created_dt) BETWEEN '19-DEC-14' AND '25-DEC-14';

Please assist.

oraclebase's picture

Databases Running in the Cloud

cloudI’ve been playing around with running databases in the cloud recently. It’s quite simplistic stuff, just to get a feel for it and investigate the possibilities of using it for some projects at work. Here’s what I’ve got so far.

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