Search

Top 60 Oracle Blogs

Recent comments

Oracle

Oracle ADB from a Jupyter Notebook

By Franck Pachot

.
My first attempt to connect to an Oracle database from a Jupyter Notebook on Google Colab was about one year ago:
https://medium.com/@FranckPachot/a-jupyter-notebook-on-google-collab-to-connect-to-the-oracle-cloud-atp-5e88b12282b0

Serial Bloom

Following the recent note I wrote about an enhancement to the optimizer’s use of Bloom filters, I received a question by email asking about the use of Bloom filters in serial execution plans:

I’m having difficulty understanding the point of a Bloom filter when used in conjunction with a hash join where everything happens within the same process.

I believe you mentioned in your book (Cost Based Oracle) that hash joins have a mechanism similar to a Bloom filter where a row from the probe table is checked against a bitmap, where each hash table bucket is indicated by a single bit. (You have a picture on page 327 of the hash join and bitmap, etc).

Oracle REST Data Services (ORDS) : Database APIs – First Steps

https://oracle-base.com/blog/wp-content/uploads/2019/12/ords-2-258x300.png 258w" sizes="(max-width: 223px) 85vw, 223px" />

In my never ending quest for automation, I finally got round to looking at the Oracle REST Data Services (ORDS) Database APIs.

Video : Multitenant : Memory Resource Management for Pluggable Databases (PDBs)

In today’s video we’ll discuss how Resource Manager allows us to manage the memory usage in PDBs. This can be useful to stop a small number of PDBs using all memory assigned to the instance.

This video was based on this article.

You might also find these useful.

Oracle 19c Automatic Indexing: Data Skew Fixed By Baselines Part II (Sound And Vision)

  In my previous post, I discussed how the Automatic Indexing task by using Dynamic Sampling Level=11 can correctly determine the correct query cardinality estimates and assume the CBO will likewise determine the correct cardinality estimate and NOT use an index if it would cause performance to regress. However, if other database sessions DON’T use […]

Oracle MAA reference architecture and HA, DR, RTO, RPO

By Franck Pachot

.
I may have mentioned in some previous blog post that, in my opinion, the names of Oracle Database features make sense on the vendor product management context more than in a user context. I’m not saying that it is good or bad. There are so many features, that can be combined, and that evolved for many years. The possible use cases is unlimited. What I see customers doing in Europe is very different from what I have seen in US companies or in Africa for example. What I’m saying is that most of the time you need a vendor-to-user dictionary when reading Oracle documentation and presentations. I’ll focus here on the MAA reference architecture. Yes, acronyms add to the complexity. MAA means Maximum Availability Architecture. Because when you have High Availability features for decades, you need another name when you bring an “higher” High Availability.

Oracle 19c Automatic Indexing: Data Skew Fixed By Baselines Part I (The Prettiest Star))

In my previous few blog posts, I’ve been discussing some issues in relation to how Automatic Indexes handle SQL statements that accesses skewed data. In this post, I’m going to setup the scenario in which Automatic Indexing can potentially use Baselines to help address some of these issues. BUT, as we’ll see, I’m having to […]

Oracle 19c Automatic Indexing: CBO Incorrectly Using Auto Indexes Part II ( Sleepwalk)

As I discussed in Part I of this series, problems and inconsistencies can appear between what the Automatic Indexing processing thinks will happen with newly created Automatic Indexing and what actually happens in other database sessions. This is because the Automatic Indexing process session uses a much higher degree of Dynamic Sampling (Level=11) than other […]

Video : Multitenant : Dynamic CPU Scaling – Resource Manager Control of CPU using CPU_COUNT and CPU_MIN_COUNT

In today’s video we’ll discuss how Resource Manager can control CPU usage in PDBs using the CPU_COUNT and CPU_MIN_COUNT parameters. Oracle call this Dynamic CPU Scaling. This can be useful to stop a small number of PDBs using all CPU resources assigned to the instance.

This video is based on the following article.

What is Object Storage?

By Franck Pachot

.
https://blog.dbi-services.com/wp-insides/uploads/sites/2/2020/09/IMG_201... 600w" sizes="(max-width: 300px) 100vw, 300px" />