December 2017

Graph Database in SQL Server 2017, Part I

I felt like playing with something new for the holidays  and chose to investigate the Graph Database feature in SQL Server 2017.

Graph Database is no simple feature, so this is going to take more than one post, but we’ll start here and see how long it takes for me to be distracted by another new feature…:)  As you can only have one user graph per database, that should limit my investigation to controlled chaos.

Oracle docker image from docker store

Did you notice that each time you want to download the Oracle binaries from the OTN website (for non-production usage) you have to click on the “Accept License Agreement”? This is because you have to agree with the OTN license agreement, and that makes it not easy to distribute an automated way to build an environment.
The only exception I have seen was the sealed envelopes provided for the RACattack:

Little things worth knowing: redo transport in Data Guard 12.2 part 1

I have researched Data Guard redo transport quite a bit, but so far haven’t really blogged about some of the details that I have worked out. This is what I am trying to do in this post.

In order to have a somewhat meaningful setup, I created a Data Guard configuration with 1 primary and 2 standby databases. They all reside on my lab (virtual) machines:

Pass Marathon on Linux for SQL Server, Wednesday, Dec. 13th

Tomorrow #0000ff;">#0000ff;" href="http://wwww.pass.org/default.aspx">Pass is sponsoring a Linux Marathon for all the SQL DBAs getting ready to go big with Linux.

iASH–my “infinite ASH” routine

I love Active Session History (ASH) data because a lot of the work I’ve done in my consulting life was “after the fact” diagnosis.  By this I mean that many of us have been in a similar circumstance where the customer will contact you not when a problem is occurring, but only when you contact them for some other potentially unrelated reason.  At which point you hear will that dreaded sentence:

“Yeah, the Order Entry screen was really slow a couple of hours ago

And this is where ASH is an awesome resource.  With the ASH data available, there is a good chance you will be able to diagnose the issue without having to make an embarrassing request for the customer to repeat the task so that you can trace the underlying database activity.  Because no-one likes to be the person that says:

“Yeah that performance must have really sucked for you … Hey, let’s do it again!”

The hang manager

Recently I was looking in the trace directory in the diag dest of my (12.2.0.1) instance, and found some trace files which were different from the others:

$ ls | grep dia0
test_dia0_9711_base_1.trc
test_dia0_9711_base_1.trm
test_dia0_9711_lws_1.trc
test_dia0_9711_lws_1.trm
test_dia0_9711.trc
test_dia0_9711.trm

The dia0 ‘test_dia0_9711.trc’ file is fully expected. But what are these ‘..lws_1.trc’ and ‘..base_1.trc’ files? And ‘base’ is something that I understand, but what would ‘lws’ mean? Lunatics Without Skateboards?

First, let’s look into the normally named trace file of the dia0 process:

SQL_ADAPTIVE_PLAN_RESOLVED Is Broken

You can use the V$SQL.IS_RESOLVED_ADAPTIVE_PLAN column to know whether the execution plan associated to a child cursor is adaptive or not. Specifically, to know whether the query optimizer selected either an adaptive join method or an adaptive star transformation (notice that it is not set when the hybrid hash distribution is involved).

The column takes one of the following values:

Welcome to pgdfv: PostgreSQL data file visualizer

Introduction

As you may know the PostgreSQL database page contains a lot of informations that is documented here. A great study has been done by Frits Hoogland in this series of blogposts. I strongly recommend to read Frits series before to read this blog post (unless you are familiar with PostgreSQL block internals).

By reading the contents of a page we can extract:

#UKOUG_TECH17

Award

ukoug_tech17_award_paul_fitton.jpgI’ve received an award for an article I’ve written last year, the Most Read Oracle Scene Article in 2016 – Technology. I like to write for Oracle Scene magazine. It is rare today to have a magazine both available in a paper version, and also publicly available on the web. And I must say that as an author, all the people behind are doing a great work. Thanks to them and thanks for the award. Seeing that what I write helps is the motivation to do so.

Shooting the DBA isn’t a Silver Bullet to the Cloud

We’ve all been watching numerous companies view value in bypassing the Database Administrator and other critical IT roles in an effort to get IT faster to the cloud.  It may look incredibly attractive to sales, but the truth of it is, it can be like setting up land mines in your own yard.