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September 2020

Toward zero: Reducing and offsetting our data center power emissions

Following the massive Australian bushfires earlier this year, I was motivated to act within my role as a data scientist at Automattic to help fight anthropogenic climate change. Together with colleagues from across the company, we formed an employee resource group focused on sustainability. We are pleased to announce that as a result of our efforts, Automattic now offsets data center power emissions produced from non-renewable sources. This means that the servers running WordPress.com, WordPress VIP, Tumblr, and other Automattic services contribute net zero carbon emissions to our shared atmosphere.

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.

Amazon Aurora Serverless (PostgreSQL compatibility)

By Franck Pachot

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I’ve written a blog post about serverless databases and here is an example of Amazon RDS Aurora PostgreSQL in serverless mode:

Do you know where your installation media is?

This was inspired by a Twitter comment and subsequent DMs, but I’m not going to name names. You know who you are… </p />
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Amazon or AWS services?

By Franck Pachot

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When I’m writing about a product I like to be precise about the name, the upper and lower case, and even more: do you know that was taking special care of writing Oracle 12cR2 before then non-italic came with 18c? And that’s also the reason I’m not writing a lot about VMware as it takes me 5 minutes to put the uppercase right </p />
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What is Object Storage?

By Franck Pachot

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Oracle 19c Automatic Indexing: CBO Incorrectly Using Auto Indexes Part I (Neighborhood Threat)

Following on from my previous few posts on “data skew”, I’m now going to look at it from a slightly different perspective, where there is an inherent relationship between columns. The CBO has difficulties in recognising (by default) that some combinations of column values are far more common than other combinations, resulting in incorrect cardinality […]

Amazon DynamoDB: a r(el)ational Glossary

By Franck Pachot

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There are many NoSQL databases. And, because SQL is an ISO standard, “No SQL” also means “No Standard”. Many have a similar API and similar objects, but with completely different names. Today, NoSQL databases are used as an additional datastore for some well-defined use cases for which a hashed key-value store fits better than a relational table. And it quickly became “Not Only SQL” as it is complementary to RDBMS databases using SQL. But at the origin, the idea was to replace the RDBMS databases, refusing the SQL API, and then inventing a “No SQL” data store. When you want to replace something rather than proposing something new, you often adopt the same language to make it look similar. And this why, in my opinion we find some relational database terms like “Table” and “Index”. But they have a different meaning. Here is a dictionary where I try to explain the DynamoDB artifacts and differentiate from their Relational and SQL meaning.

Oracle 19c Automatic Indexing: Data Skew Part III (The Good Son)

  I’m going to expand just a tad on my previous posts on data skew and run a simple query that returns a few rows based on a column predicate AND another query on the same column that returns many rows. The following table has a CODE column as with previous posts with the data […]