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Oracle

Oracle SGA memory allocation on startup

Recently I have been presenting on what running on a large intel based NUMA system looks like (OTN EMEA tour in Düsseldorf and Milan, and I will be presenting about this at the Dutch AMIS 25th anniversary event in june). The investigation of this presentation is done on a SGI UV 300 machine with 24 terabyte of memory, 32 sockets (=NUMA nodes), 480 core’s and 960 threads.

Recently I have been given access to a new version of the UV 300, the UV 300 RL, for which the CPU has improved from Ivy Bridge to Haswell, and now has 18 core’s per socket instead of 15, which means the number of core’s on a fully equipped system is 576, which makes 1152 threads.

BI Publisher will not start (using emctl oms start and emctl oms start -bip_only)

*Customer names obfuscated to protect the innocent (and the guilty!)

This post covers a particular customer’s recovery scenario. They had reverted their config.xml to a previous version due to a failed attempt to integrate LDAP into WLS myrealm, and ever since, they have been unable to start BI Publisher via the emctl command. Although they can start it from the WLS Admin Console, the ’emctl status oms -details’ shows BI Publisher Server is Down, and they can’t even connect to it via the https://em12c.example.com:9702/xmlpserver/. They then attempted to run the emcli setup_bipublisher to re-register it with EM but get:

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.

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:

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:

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:

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:

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.

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)