Log Buffer #475: A Carnival of the Vanities for DBAs

This Log Buffer Edition goes through various blogs, and selects some of the top posts from Oracle, SQL Server and MySQL.

Oracle:

MOS Note:136697.1 – New HCHECK.SQL for Oracle Database 12c

ORAchk / EXAchk questions.

Cloud control won’t start!

ASMLib is an optional utility that can be used on Linux systems to manage Oracle ASM devices.

ORA-56841: Master Diskmon cannot connect to a CELL.

Oracle BITAND Function with Examples.

 

SQL Server:

Natively (more...)

SharePlex Replication Between Two Instances On The Same Host

Several days ago I was asked a question about SharePlex and should verify behaviour before providing the answer. I had one linux VM with two databases and needed to setup replication between them. One of them (orcl) was a target 12c EE database while the second one was a source 10g SE. Accordingly, I should use two different versions of SharePlex to mimic the questionable behaviour, so I should have two different SharePlex instances talking (more...)

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”. (more...)

Transportable Tablespaces – Characters Sets – Same same but different?

All credits go to Don Wolf, an Oracle Advanced Customer Support engineer from Ohio as he dug out this information Thanks Don! Do database character sets have to match EXACTLY for Transportable Tablespaces? That sounds like a simple question. When you look into our big slide deck the answer will be a straight... [Read More]

Did You Know #14 – Bug Fixes Lists

Oracle database is a very complex software, and as we all know, has bugs. Oracle tries to address these bugs, and fixes a lot of them all the time. Except specific fixes, they publish patchsets (which might introduce more than only bug fixes) and PSUs. If you are not aware of these patch types and […]

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 (more...)

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:


CREATE TABLE M_DTX
(
        R_ID    NUMBER(3),
        R_AMT   NUMBER(5),
        DATE1   DATE,
        DATE2   DATE,
        VC GENERATED ALWAYS AS (EXTRACT(MONTH FROM DATE2))
)
PARTITION  (more...)

Accessing STATUS columns efficiently

A frequently reoccuring design problem with relational databases is the issue locating unprocessed rows in a large table, so we know which rows of data are still yet to be processed.

The problem with a STATUS column is that it generally has low cardinality; there are probably only a handful of distinct values [(C)omplete, (E)rror, (U)nprocessed or something like that]. Most records will be (C)omplete. This makes STATUS a poor candidate for standard B-Tree indexation. (more...)

OUGF Harmony 2016 Spring Conference Twitter Statistics

If you didn’t come this page from my review about the OUGF Harmony16 Spring Conference, please don’t forget to read it. This post is generated almost automatically by scripts to share the twitter statistics of the conference. The statistics cover the period between May 17 and May 20. I included three hashtags (#OUGF, #OUGF16, #Harmony16), because at the beginning of the conference, people (including me) did not used the official hashtag (#Harmony16).

openning


#Harmony16 Tweets

(more...)

OUGF Harmony 16 Spring Conference

Last week I took part in the OUGF (Oracle User Group Finland) Harmony 16 Spring Conference. It was a two day event, and held in Helsinki, between May 18th and 19th. In the conference, I gave two speeches: “Essential Linux commands for DBAs” and “Enterprise Manager 13c for DBAs”. Most people expect to me to speak about Enterprise Manager but in my first session, I spoke about the tools which can be used for monitoring (more...)

Video : Indexing JSON Data in Oracle Database 12c

Following on from last week’s post, today’s video is about indexing JSON data in Oracle Database 12c.

If videos aren’t your thing, you might want to read these articles, which the videos are based on.

The cameo in this video (more...)

Oracle DBA en SQL Celebration Day June 7th, 2016

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

RMAN-06172 when restoring a controlfile and dNFS is not turned on

Oracle EE 11.2.0.4 on Linux x86-64.

I got a really surprising error message today when setting up a new data guard standby database.
I created a standby controlfile as usual and placed it on a common NFS share accessible also to the new data guard host:

SQL> alter database create standby controlfile as '/nfs/install/oemdb/cf2.f';

Database altered.

Now, on a new node I tried to restore that controlfile, but got a really (more...)

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. (more...)

Oracle ASMLib

This blog post is more of a note for myself on configuring ASMLib.

ASMLib is an optional utility that can be used on Linux systems to manage Oracle ASM devices.

ASMLib consists of the following components:

An open source (GPL) kernel module package: kmod-oracleasm
An open source (GPL) utilities package: oracleasm-support
A closed source (proprietary) library package: oracleasmlib

On my Oracle VMBox, I performed the below steps –

1. Check the installed packages related to (more...)

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, (more...)

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.

change

Configuration Management, EM12c to EM13c

As requests came in for me to write on the topic of Configuration Management, I found the EM13c documentation very lacking, having to push (more...)

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)

Node-oracledb 1.9.1 with Promises and Node 6 Support is on NPM

| May 18, 2016
Top features: Promise support. Node 6 support. The new node-oracledb 1.9.1 release adds Promise support, it now supports the new Node 6 (as well as previous releases), and it has some welcome stability fixes. Other nice goodies are mentioned below. Thanks to everyone who gave feedback on our 1.9.0 development... [Read More]

Oracle Midlands : Event #15 – Summary

Last night was Oracle Midlands Event #15 with Joel Goodman and Martin Widlake.

First up was Joel with a session called, “Oracle Storage Fragmentation”, where he discussed the potential fragmentation issues possible in tablespaces, tables and indexes. If you’ve been a DBA for a long time it’s easy to think everyone knows this stuff, but I get asked questions about this stuff a lot! The session had a good mix of content, with something to (more...)