Stats Collection Time Anomaly

Johnathan Lewis (@JLOracle) recently published a short post about Stats Collection Time, talking about the table dba_optstat_operation (and dba_optstat_operation_tasks ), which reminded me about (what I regard as) an anomaly in the output in the NOTES columns in Oracle 12C.

I won’t repeat why it’s useful to check these tables as Johnathans note and @MDWidlakes’s comment here should give you all you need to know.

The DBA_OPTSTAT_OPERATION.NOTES column contains the (more...)

Stats collection time

Yesterday I posted a note about querying dba_optstat_operations to get a quick report of how long calls to dbms_stats had been taking but said I had another script that helped to fill some of the gaps it left. One of my readers points out fairly promptely that 12c enhances the feature considerably, with a view dba_optstat_operation_tasks that (for example) lists all the tables processed during a single call to gather_schema_stats.

Well, I wrote my script (more...)

Do You Even TDM, (Test Data Management)?

Along with the deep learning I’ve been allowed to do about data virtualization, I’ve learned a great deal about Test Data Management.  Since doing so, I’ve started to do some informal surveys of the DBAs I run into and ask them, “How do you get data to your testers so that they can perform tests?”  “How do you deliver code to different environments?”

confused

As a basic skill (more...)

Spark 2.0 Performance Improvements Investigated With Flame Graphs

Topic: This post is about performance optimizations introduced in Apache Spark 2.0, in particular whole-stage code generation. A test case is introduced and investigated with diagnostic tools.


Introduction: performance troubleshooting of a slow query using parallel query execution in a Hadoop cluster

The idea for this post comes from a performance troubleshooting case that has come up recently on our database services. It started with a user reporting slow response time from a query (more...)

Upgrade yourself from DBA to DMA

In any profession, learning never ends. From my very personal perspective and own exprience, I strongly beleinv in one who upgrade his skills always stays a step ahead from the rest. To stay competitive, it is necessary to upgrade our skills according the market demand.

For DBA folks who aim and dream to learn and upgrade their knwoledge with Oracle Exadata technologies, I wrote a 5 series article to Toad, below are the links to (more...)

Stats time

I don’t really remember how long it’s been since Oracle created an automatic log of how long a call to the dbms_stats package took, though it was probably some time in the 10g time-line. It wasn’t until it had been around for several years, though before I wrote little script (possibly prompted by a comment from Martin Widlake) that I’ve used occasionally since to see what’s been going on in the past, how variable (more...)

Installing a 12.1.0.5 agent on a Linux 5.x platform from a 13.1 OMS

Is that enough version numbers for you? 🙂

The issue this post will address (very briefly because it’s the week before OOW2016 and life is crazy!) is this. If you are running a 13.1 version of the OMS, and you try to push a 12.1.0.5 agent to a Linux box that’s running some version of 5.x (such as RHEL5 or OL5), you will get an error message saying you are (more...)

E-book: Discover the breakthrough innovations in Oracle Database 12c

Download the eBook and read to learn about 12c (the next generation most popular database) :

  • Simplify database consolidation and manage them as cloud services
  • Accelerate analytical performance whilst achieving new levels of efficiency, security and availability
  • Lower cost and mitigate risk




Install OEM 13c Silent mode

How to install Oracle EM 13c? It's the first time that I have a chance to install Oracle EM 13c. I remember last time I installed Oracle EM 12c. I have to install weblogic first. On OEM 13c, I don't need to do something like that. It installs WLS -12.1.0.3 , JDK – 1.7.0_80. 
In this post, I installed Oracle EM 13c Silent mode with "SMALL" deployment. I assume, I installed (more...)

Spark 2.0 Performance Improvements Investigated With Flame Graphs

Topic: This post is about performance optimizations introduced in Apache Spark 2.0, in particular whole-stage code gen

Before Investing in Data Archiving, Ask These Questions

Data has a way of growing so quickly that it can appear unmanageable, but that is where data archiving shines through.  The tool of archiving helps users maintain a clear environment on their primary storage drives.  It is also an excellent way to keep backup and recovery spheres running smoothly.  Mistakes and disasters can and will happen, but with successful archiving, data can be easily recovered so as to successfully avert potential (more...)

Finding the Right Tools to Manage Data in Today’s Modern World

A common concern among companies is if their resources are being used wisely.   Never before has this been more pressing than when considering data storage options.  Teams question the inherent worth of their data, and often fall into the trap of viewing it as an expense that weighs too heavily on the budget.  This is where wisdom is needed with respect to efficient resource use and the task of successful data storage. (more...)

addNode.sh, failed root.sh and IB listener

So this customer has an Exadata quarter rack and they have an IB listener configured on both DB nodes (for DB connections from a multi-racked Exalogic system). We were adding a new DB node to this rack. So just followed the standard procedure of creating users, directories etc on the new node, setting up ssh equivalence and running addNode.sh. All went fine but root.sh failed. Little looking into the logs revealed that it (more...)

Securefile space

A script hacked together a couple of years ago from a clone of a script I’d been using for checking space usage in the older types of segments. Oracle Corp. eventually put together a routine to peer inside securefile LOBs:

rem
rem     Script:         dbms_space_use_sf.sql
rem     Author:         Jonathan Lewis
rem     Dated:          Dec 2013
rem     Purpose:
rem
rem     Last tested
rem             12.1.0.1
rem             11.2.0.4
rem     Not tested
rem             11.1. (more...)

Oracle Service Secrets: Migrate Transparently

Databases or schemas tend to get moved around between different servers or even datacenters for hardware upgrades, consolidations or other migrations. And while the work that needs to be done is pretty straight forward for DBAs, I find the most annoying aspect of that is updating all client connect strings and tns entries used with new IP addresses and – if not using services – also the SID as the instance name might have changed.

(more...)

Oracle Database – JSON en de In-Memory Database

Op maandag 24 oktober vindt er een bijeenkomst plaats over JSON en de In-Memory Database…

Posts by Alberto Dell’Era On ASH Wait Times And Materialized Views

This is just a short note that links to different articles on Alberto Dell'Era's blog. Alberto is a long time member of the OakTable and has published a number of posts I find very useful and therefore are linked here:

ASH wait times (including an ASH simulator!)

Posts on Materialized Views

Basicfile LOBs 6

One of the nice things about declaring your (basicfile) LOBs as “enable storage in row” is that the block addresses of the first 12 chunks will be listed in the row and won’t use the LOB index, so if your LOBs are larger than 3960 bytes but otherwise rather small the LOB index will hold only the timestamp entries for deleted LOBs. This makes it just a little easier to pick out the information you (more...)

Basicfile LOBS 5

At the end of the last installment we had seen a test case that caused Oracle to add a couple of redundant new extents to a LOB segment after one process deleted 3,000 LOBs and another four concurrent processes inserted 750 LOBs each a few minutes later (after the undo retention period had elapsed). To add confusion the LOBINDEX seemed to show that all the “reusable” chunks had been removed from the index which suggests (more...)

Space Usage

Here’s a simple script that I’ve used for many years to check space usage inside segments.  The comment about freelist groups may be out of date  – I’ve not had to worry about that for a very long time. There is a separate script for securefile lobs.


rem
rem     Script:         dbms_space_use.sql
rem     Author:         Jonathan Lewis
rem     Dated:          Nov 2002
rem     Purpose:
rem
rem     Last tested 
rem             12.1.0.1
rem             11.2. (more...)