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April 2020

What’s new with Oracle database 19.7 versus 19.6

This blogpost takes a look at the technical differences between Oracle database 19 PSU 6 (january 2020) and 7 (april 2020). This gives technical specialists an idea of the differences, and gives them the ability to assess if the PSU impacts anything.

Functions

Friday Philosophy: The Intersecting Worlds Around Oracle

Some of you may have noticed something about the Oracle Community: How certain other aspects of human nature, factors, and outside activities are unusually common.  An abiding love of the works of Douglas Adams (If you have never read “The Hitch Hikers Guide To The Galaxy” you should question if you are right for this community – and if you have read it/seen the series/watched the film and disliked it, I’m afraid you have to leave now); Lego was probably an important part of your childhood (and quite possibly your adulthood, though some “project” this fixation on to their kids). A lot of the most talented people, especially presenters, are called “Martin” or similar :-}.

AWS Certified Database Specialty (DBS-C01)

Here is my feedback after preparing and passing the AWS Database Specialty certification. There are tips about the exam but also some thoughts that came to my mind during the preparation when I had to mind-shift from a multi-purpose database system to purpose-built database services.

Conversion Errors

I’ve been meaning to write this note for at least three years and was prompted to write up my draft notes this morning as a follow-up to yesterday’s note on the perils of applying a to_date() function to a date column. But then I took a look at the most recent questions on the Oracle Developer Forum and discovered that Tim Hall (@oraclebase) had (inevitably) already done the necessary write-up, so I’ve just left a brief note here (more for my own benefit than anything else) of the highlights with a link to his page.

Key features available in 12.2 to avoid conversion errors are:

SQL Plus … the sweet spot

Need to get a bunch from rows out of the database? Most people are aware of the ARRAYSIZE parameter to improve the fetch performance back to the client, but many people are not aware of the newer ROWPREFETCH parameter.

Let’s take a look at each to see how quickly we can drag data back to our SQL Plus client. I’ll start with table called TX which is approximately 1500MB in size, and has just over 10millions.

First let’s look at the benefits you get from ramping up ARRAYSIZE. I’ll start with the default size of 15, and quickly you’ll see why that is not a good starting point if you are fetching lots of rows. (Important emphasis on the “if” there)

OSWatcher as included in AHF 20.1.2 fails to start for single instance Oracle

I am about to update my posts detailing the use of Tracefile Analyzer (TFA) now that Oracle has merged it into its Autonomous Health Framework (AHF) and came across an interesting observation worth blogging about upfront.

After completing a fresh installation of AHF 20.1.2, the current version at the time of writing, I noticed OSWatcher didn’t start on my VM. I am operating a single instance Oracle 19.7.0 database, running on Oracle Linux 7.8/UEK 5. The system does not contain any traces of Grid Infrastructure.

I fully expect this problem to be transient, but until Oracle provides a fix I wanted to share my workaround. I didn’t find this problem covered in the usual sources, including My Oracle Support.

For the record, this is the version I can confirm to be affected:

What’s new with Oracle database 18.9 versus 18.10

This blogpost takes a look at the technical differences between Oracle database 18 PSU 9 (january 2020) and 10 (april 2020). This gives technical specialists an idea of the differences, and gives them the ability to assess if the PSU impacts anything.

Functions

date_to_date

Every now and again someone posts a piece of SQL on the Oracle Developer Forum that includes a predicate with an expression like to_date(date_column). This is a problem for several reasons – not the least being the type of performance problem that showed up in a post from a couple of years back that has just been resurrected.

Before I examine the performance detail, here’s a simple demo of the “wrong data” problem that can go unnoticed, cut-n-paste from a 12.2.0.1 session of SQL*Plus:

What’s new with Oracle database 12.1.0.2.200114 versus 12.1.0.2.200414

This blogpost takes a look at the technical differences between Oracle database 12.1.0.2 PSU 200114 (january 2020) and 200414 (april 2020). This gives technical specialists an idea of the differences, and gives them the ability to assess if the PSU impacts anything.

Parameters
The list of parameters removed (first) and parameters added (second) is remarkable long.
It’s striking that a lot of solutions for bugs made configurable (_bug[0-9]*_.*) have been removed, and probably returned back as ‘spare parameters’.
Also some in memory (_inmemory.*) parameters have been removed.
Also some documented parameters; exafusion_enabled and optimizer_adaptive_plans and optimizer_adaptive_statistics, plus some standby parameters I wasn’t aware of existing.