Dead Connection Detection (DCD) and the Oracle database

Dead Connection Detection is a useful feature of the Oracle database: it allows for the cleanup of “dead” sessions so they don’t linger around consuming memory and other system resources. The idea is simple: if the database detects that a client process is no longer connected to its server process, it cleans up. This can happen in many ways, in most cases this kind of problem is triggered by an end user.

A dead connection (more...)

Little things worth knowing: keeping enq: TM enqueue at bay during direct path inserts

Direct path inserts are commonly found in processing where data are shifted from one source to another. There are many permutations of the theme, this post details the way SQL Loader (sqlldr) behaves.

I have previously written about sqlldr and concurrent direct path inserts. The behaviour for releases <= 12.1 is described in the first post, the most welcome changes in 12.2 went into the second post. Since the fastest way of (more...)

ORA-14300 partitioning key maps to a partition outside maximum permitted number of partitions and NULLs

While researching interval partitioning in Oracle 19c I came across a phenomenon I had already solved a long time ago but then forgot about. This time I decided to write about it so I don’t have to spend 5 minutes rediscovering the wheel. As always, if you are following along, make sure you are appropriately licensed for this feature

The Situation

Consider the following example:

SQL*Plus: Release 19.0.0.0.0 - Production on  (more...)

sqlldr, direct path loads and concurrency in 12.2 and later

In my previous post I showed you that Oracle’s SQL loader (sqlldr) utility has a built-in timeout of 30 seconds waiting for locked resources before returning SQL*Loader-951/ORA-604/ORA-54 errors and failing to load data. This can cause quite some trouble! Before showing you the enhancement in 12.2 and later, here is the gist of the previous post.

Concurrency in Oracle sqlldr 12.1 and earlier

To show you how sqlldr times out I need to (more...)

sqlldr, direct path loads and concurrency in 12.1 and earlier

I have recently come across an interesting issue related to concurrent data loading into the Oracle database using sqlldr’s direct path mode. Although I investigated the situation on 12.1.0.2, I found that the same holds true in 19.4 as well when using the defaults. I reconstructed the case, although it is simplified a little to bring the point home.

The environment I used to put this post together is Oracle Restart (more...)

Ansible tips’n’tricks: checking if a systemd service is running

I have been working on an Ansible playbook to update Oracle’s Tracefile Analyser (TFA). If you have been following this blog over the past few months you might remember that I’m a great fan of the tool! Using Ansible makes my life a lot easier: when deploying a new system I can ensure that I’m also installing TFA. Under normal circumstances, TFA should be present when the (initial) deployment playbook finishes. At least in theory.

(more...)

RBAL (ospid: nnn): terminating the instance due to error 27625 after patching Oracle Restart

I have come across an odd behaviour trying to patch an Oracle Restart environment to 12.1.0.2 January 2019. Based on a twitter conversation this isn’t necessarily limited to my patch combination, there might be others as well. I have used opatchauto to apply patch 28813884 to both RDBMS and GRID homes plus its corresponding OJVM (Java) patch. Before diving into details, this is the environment I have been working with:

JSON_TABLE() and date/time columns in Oracle 19c

While researching the use of JSON in Oracle 19c I came some interesting behaviour that wasn’t immediately obvious (to me). With this post I am hoping to save you a couple of minutes scratching your head when working with JSON_TABLE(). This is Oracle 19.3.0 on Linux and I’m connecting to it using SQLcl 19.1.

Some background

As part of my JSON-support-in-Oracle research I had a good look at JSON_TABLE. Although complex at (more...)

Why does my REST Services menu not show up in SQL Developer?

Oracle SQL Developer has excellent support for Oracle Restful Data Services (ORDS). A lot of the functionality is just a mouse click away. With so many people speaking about RESTful APIs I wanted to see what they are like. However, when I first tried to use SQL Developer to administer ORDS in the database I was surprised at first to not find the menu item to do so. This post might be stating the (insert (more...)

Learning Kubernetes: persistent storage with Minikube

As part of my talk at (the absolutely amazing) Riga Dev Days 2019 I deployed Oracle Restful Data Services (ORDS) in Minikube as my application’s endpoint. I’ll blog about deploying ORDS 19 in docker and running it on Kubernetes later, but before I can do so I want to briefly touch about persistent storage in Minikube because I saw it as a pre-requisite.

In a previous post I wrote about using Minikube as a runtime (more...)