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Finally Getting Broadband – Via 4G! (cable-free, fast-ish internet)

I live in a field. Well, I live in a house, but it and a few other houses make up a tiny hamlet surrounded by fields. My back garden is itself a small field. It’s nice to live surrounded by countryside, but one of the drawbacks of this rural idyll is our internet connection. Our house is connected to the World Wide Web by a copper telephone line (via a British Telecom service), and it’s not a very good copper telephone line either. I joke that wet, hairy string would be just as useful. Our connection speed is, at best, about 5Mbps download and 0.4Mbps upload. That is not a typo – nought point four megabits a second. My dual ISDN line back in 2003 could just about manage that. At busy times it’s worse – a lot worse – as all the houses in our hamlet contend for whatever bandwidth we have back to civilisation. Evenings & weekends it has almost become a not-service. It is not broadband, it’s narrowband.

Video : Partial Indexes for Partitioned Tables

In today’s video we demonstrate partial indexes for partitioned tables, introduced in Oracle database 12.1.

The video is based on this article.

The star of today’s video is Carry Millsap, who is being lead astray by a very naughty James Morle.

Cheers

Tim…

Datatype conversions – strange internal function

Perhaps the most famous (or infamous) performance tuning problem you’ll find spanning decades of blog posts when it comes to Oracle and SQL is the “mystery” of why Oracle is not using an index when it is totally obvious to us as the developer that it should be.  The demo code is always along the following lines

How long will the script take to run?

In a world where databases are now the norm, whereas distributing data via a CSV file used to be commonplace, nowadays we often see the ubiquitous INSERT script being offered as a means to seed data. This is perfectly fine for those requirements where we are populating a finite list of reference data that is often required by an application to run for the first time. Things like list of valid genders, list of valid states or counties, list of valid post/zip codes, etc. They are all typically sourced from an owning authority, don’t change frequently over time, and even when they do, it is typically sufficient to manually make a correction to your database.

CockroachDB troubleshooting series… define the process

After working with customers for about 18 months now, I am starting a blog series to write up the common issues seen while running CockroachDB. Diagnosis and treatment of issues when running on distributed database architectures like CockroachDB, closely mirror the process used in the medical community.

There are observed symptoms which leads to a diagnosis and finally a treatment to resolve the condition. Good troubleshooting methodology can help frame the problem which leads to better overall outcomes. This process is outlined below:

Scaling CockroachDB key generation… uuid, serial, and sequences

Overview

Primary keys are critical in any RDBMS in order to ensure the validity of data. Unlike other distributed SQL databases, CockroachDB is not sharded by primary key to distribute the data. Data is divided to ranges and distributed automatically among nodes in the cluster. CockroachDB ranges are sorted by the primary key values. So, while the value doesn’t define the distribution, the sorting of the values can have implications if you use sequences that increment values in a counter-like fashion. This will put stress on a single RANGE of data which scaling of a distributed application.

Video : Adaptive Cursor Sharing

In today’s video we’ll discuss the Adaptive Cursor Sharing feature, introduced in Oracle 11g Release 1.

This video is based on the following article.

Here are some other things you might want to check out.

Video : CURSOR_SHARING : Automatically Convert Literals to Bind Variables in SQL Statements

In today’s video we’ll discuss the CURSOR_SHARING parameter, which determines how the database handles statements containing literal values.

The video is based on this article.

You may also find these useful.

rowsets

Here’s a little demonstration of the benefit of rowsets. It started with a very simple question that arrived in my in-box from Kaley Crum.

  • “Why does the query with the UNION ALL take so much longer than the query without the UNION ALL?”

Here are the two queries – surely they should take virtually the same amount of time.