Epoch

Note to self because it’s just one of those date/timezone-related topics which just doesn’t seem to stick…

Epoch/Unix time – See https://en.wikipedia.org/wiki/Unix_time

Unix time (also known as POSIX time or erroneously as Epoch time) is a system for describing instants in time, defined as the number of seconds that have elapsed since 00:00:00 Coordinated Universal Time (UTC), Thursday, 1 January 1970,

Firstly when converting from Oracle date or timestamp – we need to (more...)

Index Tree Dumps in Oracle 12c Database (New Age)

I’ve previously discussed Index Tree Dumps but I’ve recently found a nice little improvement that’s been introduced in Oracle Database 12c. Let’s begin by creating a little table and index: To generate an Index Tree Dump, we first need to OBJECT_ID of the index: And then use it to generate the Index Tree Dump: Previously, an […]

Event Histogram Metric and Oracle 12c

Topic: event histogram metric, a script and some related comments on collecting and displaying wait event latency histograms for Oracle performance troubleshooting.

Why: Latency histograms (and by extension wait event histograms) provide very useful information when troubleshooting performance for systems exhibiting response time with multi-mode distribution. In such cases average wait values are often not sufficient to understand the behavior of the system under study and histograms provide a finer level of details. A (more...)

Oracle Database 12c: Interactive Quick Reference

12c DB Architecture


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Warning: standby redo logs not configured for thread – BUG

Surprise to find the following error for single instance Data Guard environment:

    Warning: standby redo logs not configured for thread 3 on boston

 

This will be fixed with an upcoming patch for the existing issue in Oracle Database 12.1.0.1.0 – good reason to stay up to date on patching?

Also, the number of Standby Redo Log Groups do not match since thread = 1 is being used.

Not *ALL* SRL have thread (more...)

SQL Plan Baseline Manual Evolution

I’ve never really spent time on evolution because most of the time I use baselines for emergency sql plan management and not with the added value of controlled evolution with which the feature was conceived.

But some observations on sql plan baseline evolution originating from the questions:

  • What does evolution actually do?
  • What information does it use?
  • What happens with DML?

Starting point – one baselined plan

1. FTS plan in memory from SQL which (more...)

With PL/SQL and LONGs (and PRODUCT_USER_PROFILE)

One use for the 12.1.0.2 addition of PL/SQL functions in the WITH clause is to get the HIGH_VALUE of a partition in a usable column format.

with
 FUNCTION char2000(i_tab in varchar2, i_part in varchar2) 
 RETURN VARCHAR2 IS
   v_char varchar2(2000);
 BEGIN
   select high_value into v_char
   from user_tab_partitions a
   where a.table_name = i_tab
   and a.partition_name = i_part;
   --
   if v_char like 
     'TO_DATE(''%'', (more...)

Loading JSON data into Oracle using ROracle and jsonlite

In this post I want to show you one way of taking a JSON file of data and loading it into your Oracle schema using ROracle. The JSON data will then be used to create a table in your schema. Yes you could use other methods to connect to the database and to create the table. But ROracle is by far the fastest method of connecting, selecting and processing data.

1. Necessary R Packages

You (more...)

Finding the Oracle Database Appliance Plug-in within #em12c

The Oracle Database Appliance (ODA) has been around for a few years now. It is a great, compact, and powerful machine for running at two-node Oracle Real Application Cluster (RAC). The adoption of the ODA has been mostly seen in medium sized organizations that need a work horse but cannot afford the sticker price of an Oracle Exadata.

Just like all the appliances that Oracle puts out, there is a need to monitor these appliances (more...)

Oracle Data Miner (ODM 4.1) New Features

With the release of SQL Developer 4.1 we also get a number of new features with Oracle Data Miner (ODMr). These include:

  • Data Source node can now include data sources that contain JSON data, generating JSON schema and has a JSON viewer
  • Create Table can now create data in JSON
  • JSON Query Node allows you to view, query and process JSON data, combine it with relational data, generate sub-group by, and nested columns to (more...)

Strategies for Minimising SQL Execution Plan Instability

Execution Plan Instability – What is the problem?

The Oracle Optimizer is a complex piece of software and with every release it becomes more complex.

RBO

In the beginning, the Optimizer was rule-based.

The Optimizer had a ranked list of heuristics used to optimize a query, picking the lowest ranked rule available.

This rule-based mode, whilst still in use with some internal Oracle dictionary queries, has been unsupported since version 10.1.

This means that (more...)

Viewing Models Details for Decision Trees using SQL

When you are working with and developing Decision Trees by far the easiest way to visualise these is by using the Oracle Data Miner (ODMr) tool that is part of SQL Developer.
Developing your Decision Tree models using the ODMr allows you to explore the decision tree produced, to drill in on each of the nodes of the tree and to see all the statistics etc that relate to each node and branch of the (more...)

Oracle Database 12c Interactive Quick Reference

You may remember days when you had huge Oracle posters on your cubicle wall that listed the various data dictionary views, or the underlying Oracle architecture.  Maybe you still have them.  For the 12c version of the database Oracle provides the Oracle Database 12c: Interactive Quick Reference.
The Quick Reference provides information on:

  • DBA Views
  • Performance Views
  • Architecture Views
  • Database Architecture
  • Multitenant Architecture
  • Background Processes

As part of the Quick Reference there are Architecture .pdfs (more...)

Changing REVERSE Transformations in Oracle Data Miner

In my previous blog post I showed you how you can have a look at the transformations that the Automatic Data Preparation (ADP) feature of Oracle Data Mining produces. I also gave some example of the different types of ADF that are performed for different algorithms.

One of the features of the transformations produced is that it will generate a REVERSE_EXPRESSION. This will take the scored results and apply the inverse of the transformation that (more...)

ODM : View Transformations generated by Automatic Data Prepreparation

A very powerful feature of Oracle Data Mining and one that I think does not get enough notice is called Automatic Data Preparation.

Data Preparation is one of the most time consuming, repetitive and boring parts of the work that a Data Miner or Data Scientist performs as part of their daily tasks. Apart from gathering the data, integrating the data, getting the data into the required formation the most interesting part of the work (more...)

OTech article on Predictive Queries

Last week the Spring 2015 edition of OTech Magazine was published.

Check out the link to the it here.

Otech 1

I was lucky to have an article accepted and published in this edition and the topic of the article was on Predictive Queries.

I've given a presentation on Predictive Queries at a few Oracle User Group conferences over the past 6 months or so, and this article covers what I talk about in that presentation.

The (more...)

Oracle Database In-Memory Test Drive Workshop: Canberra 28 April 2015

I’ll be running a free Oracle Database In-Memory Test Drive Workshop locally here in Canberra on Tuesday, 28th April 2015. Just bring a laptop with at least 8G of RAM and I’ll supply a VirtualBox image with the Oracle Database 12c In-Memory environment. Together we’ll go through a number of hands-on labs that cover: Configuring the Product Easily […]

Configuring Oracle #GoldenGate Monitor Agent

In a few weeks I’ll be talking about monitoring Oracle GoldenGolden using Oracle Enterprise Manager 12c at IOUG Collaborate in Las Vegas.  This is one of the few presentations I will be giving that week (going to be a busy week).  Although this posting, kinda mirrors a previous post on how to configure the Oracle GoldenGate JAgent, it is relevant because:

1. Oracle changed the name of the JAgent to Oracle Monitor Agent
2. Steps (more...)

Access Denied when logging in to OSB 12c console

The Oracle SOA Suite 12c quick start is an excellent way to get started with all the new features of 12c. I imagine it must be frustrating when you log in to http://localhost:7101/servicebus and are confronted with an 401 – Access Denied error message. Rest assured, there is nothing wrong with your credential configuration. The cause is likely much more simple; you use the wrong Java version.

Although the certification matrix for FMW 12.1. (more...)

Showing Interval Partitons Code in DBMS_METADATA.GET_DDL


-- If you want to display the system generated partitions as part of the CREATE TABLE DDL, then set the EXPORT parameter of the dbms_metadata to true.

-- The default behavior of "DBMS_METADATA.GET_DDL" is that it does not show Interval Partitions created by the system for interval partitioned tables and indexes.

-- In the case of Interval Partitioning, New Partitions are created automatically when corresponding row is inserted.  This newly created partition information (more...)