Oracle

Jonathan Lewis's picture

CBO++

While browsing the web recently for articles on the HyperLogLog algorithm that Oracle uses for some of its approximate functions, I came upon a blog post written in Jan 2014 with the title Use Subqueries to Count Distinct 50X Faster. There are various ways that subqueries can be used to rewrite queries for improved performance, but when the title caught my eye I couldn’t think of a way in which they could improve “count distinct”.  It turned out that the word “subquery” was being used (quite correctly) in the sense of “inline view” while my mind had immediately turned to subqueries in the select list or where clause.

pete.sharman's picture

Enterprise Manager 13c and AWS

This posting is to try to clarify what is supported when using Enterprise Manager Cloud Control 13c (EM13c) and Amazon Web Services (AWS). The question came from some of our sales consultants who were finding confusing information about what is actually supported when using EM13c and AWS, so I have asked our Support folks to write a support note to provide the definitive answer on this. While that is being written, I thought I would post a quick blog that could be used to help clarify matters.

So let’s look at what the different scenarios are:

Jonathan Lewis's picture

Virtual Partitions

Here’s a story of (my) failure prompted by a recent OTN posting.

The OP wants to use composite partitioning based on two different date columns – the table should be partitioned by range on the first date and subpartitioned by month on the second date. Here’s the (slightly modified) table creation script he supplied:

marco's picture

Oracle DBA and SQL Celebration Day June 7th, 2016

On Tuesday, June 7th, 2016 the Dutch Oracle Usergroup (OGh) will organize the Oracle DBA…

pete.sharman's picture

ORAchk / EXAchk questions

Yesterday I wrote a post on the ORAchk / EXAchk plug-in in Enterprise Manager Cloud Control 13c, and I promised I would write another post that would cover some of the more frequently asked questions we’ve been receiving on the plug-in. That’s what this post in, so the rest of the post will be in a Q&A sort of format.

Question: What are the benefits of EXAchk integration with the Enterprise Manager compliance framework i.e. what can we do with this that we could not in EM12c?

Answer: In EM 12c, we ask customers to setup EXAchk in the target themselves, we just bring the results to EM and show the results on the EXAchk target Home page. In 13c these are our main features:

pete.sharman's picture

Engineered Systems Healthchecks Plug-in (ORAchk)

In Enterprise Manager Cloud Control 12c release 12.1.0.3, we released the Oracle Engineered System Healthchecks plug-in which processed the XML output from the EXAchk tool, included as part of Oracle Enterprise Manager system monitoring. The EXAchk tool provides functionality for system administrators to automate the assessment of Engineered Systems for known configuration problems and best practices.

Over the years since that first release, we increased the scope and functionality of the tool, to the stage where it now has its own documention guide, Enterprise Manager ORAchk Healthchecks Plug-in User’s Guide. Notice there’s no mention of the word “EXAchk” in that title. That’s because the plug-in has been expanded so far it now includes two health check tools:

dbakevlar's picture

Changes to Configuration Management in EM13c

Change is difficult for technical folks.  Our world is always moving at blinding speed, so if you start changing things that we don’t think need to be changed, even if you improve upon them, we’re not always appreciative.

iggy_fernandez's picture

The best idea since 1992: Putting the C into ACID (We need your vote)

Oracle Rdb (only available for the VMS platform) supports SQL-92 assertions (http://community.hpe.com/hpeb/attachments/hpeb/itrc-149/22979/1/15667.doc) so why not Oracle Database? Let’s put the “C” into “ACID.”(read more)

martin.bach's picture

Experimenting with the ZFSSA’s snapshot capability using the simulator

Recently I have been asked how the Copy-on-Write cloning works on the ZFS Storage Appliance. More specifically, the question was about the “master” copy: did it have to be static or could it be rolled forward? What better than a test to work out how it works. Unfortunately I don’t have an actual system available to me at home so I had to revert to the simulator, hoping that it represents the real appliance accurately.

Setup

First I downloaded the ZFS Storage Appliance Simulator from the Oracle website and created a nice, new, shiny storage system (albeit virtual). Furthermore I have an Oracle Linux 7 system with UEK3 that will attach to the ZFSSA using dNFS. The appliance has an IP address of 192.168.56.101 while the Linux system is accessible via 192.168.56.20. This is of course a virtual toy environment, a real life setup would be quite different using IPMP and multiple paths preferably over Infiniband.

Configuration

Hotsos 2016 Recap

I wanted to go to Hotsos Symposium for quite some time, having heard so many great topics from there for years. And every time I was a bit lazy to think about what I can talk about. Apparently I thought that everything I know is well covered elsewhere, so why would I be accepted. Plus all these complexities of budget, getting a visa, travel arrangements, jet lag, and personal matters in between. Last year, when call for papers was still open, I realized that there’s a good chance I can make it to Hotsos in 2016: I had a budget, visa is a doable thing, and most importantly I knew I had a topic to talk about which most likely will not be in competition with other speakers.

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