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Displaying posts with tag: Technical Track (reset)
Log Buffer #511: A Carnival of the Vanities for DBAs

This Log Buffer Edition covers Oracle, SQL Server, MySQL.

Oracle:

A Sneak Peek at Oracle’s Chatbot Cloud Service and 5 Key Factors Necessary for Bot ROI

Oracle JET Hybrid – NavDrawer Template Menu/Header Structure

Oracle Enterprise Linux 6.6 AMI Available on AWS

Datascape Podcast Episode 9 – What’s Up with Oracle These Days?

Sequential Asynchronous calls in …

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Multi Tb migration Using mydumper

In this post I will explain how to transfer a multi terabyte size database between two MySQL instances using mydumper, which is a logical backup and restore tool that works in parallel. I will also cover the case where you need to transfer only a subset of data.

Big tables are often problematic because of the amount of time needed to do mysqldump/restore which is single threaded. It is not uncommon for this type of process to take several days.

From MySQL 5.6 and on, we also have transportable tablespaces, but there are some limitations with that approach.

Physical backups (e.g. xtrabackup) have the advantage to be faster, but there are some scenarios where you still need/want a logical backup (e.g migrating to RDS/Aurora/Google Cloud SQL).

Steps Install mydumper/myloader

The first thing …

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Understanding MySQL Isolation Levels: Repeatable-read

Isolation levels are a rare subject in MySQL literature. The documentation provides a terse description and focuses mainly on locking issues, but does not discuss the semantics of each isolation level. This is not only a problem that affects MySQL documentation but also the SQL standard itself.

Both the lack of documentation and the absence of a deeper description of the expected behavior in the SQL standard make isolation levels a topic that is more assumed than known by database administrators and developers. In this blog post, I aim to help you understand how the default isolation level in MySQL works and show you some surprising facts about it.

But first let’s see how isolation levels are described in the standard: “The transaction isolation level of a SQL-transaction defines the degree to which the operations on SQL-data, or schemas in that SQL-transaction are affected by the effects of and can affect operations on …

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Log Buffer #510: A Carnival of the Vanities for DBAs

This Log Buffer Edition covers Oracle, SQL Server and MySQL.

Oracle:

Passing Single Quotes in DBMS Assert Package

Oracle E-Business Suite and Java Web Start. Finally!

Bug 18411339 – Low performance V$ARCHIVE_GAP (11.2.0.4) fix 12.2.0.1

Interactive Report Download Button only for a certain Authorization Role

The Case for …

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Log Buffer #509: A Carnival of the Vanities for DBAs

This log buffer edition covers Oracle, MySQL, and SQL Server.

Oracle:

Proactively Manage Contracts, Policies, Web Assets, and Sales Content stored in Oracle WebCenter with Fishbowl’s Subscription Notifier

Querying Custom Object Records Using RESTful Web Service Calls In Groovy Scripts

Understand the importance of OFSAA Loan Loss Forecasting and Provisioning

Oracle Database on the Docker …

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Using Transportable Tablespaces with Partitioned Tables

Overview

In this post I will explain how to transfer a partitioned table using transportable tablespaces on MySQL 5.6. Note that the operation is not officially supported until MySQL 5.7, as the discard tablespace operation will fail if it is run against a partitioned table on MySQL 5.6.

The workaround is transferring each individual partition as if it was a standalone table. Continue reading to learn more about the detailed procedure.

Steps

1. Create the same table structure on the destination server:

[root@mysqlsandbox ~]# mysql
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.6.35-80.0 Percona Server (GPL), Release 80.0, Revision f113994f31

Copyright (c) 2009-2016 Percona LLC and/or its affiliates
Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. …
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Log Buffer #508: A Carnival of the Vanities for DBAs

This Log Buffer Edition covers Oracle, SQL Server and MySQL.

Oracle:

Compiling views: When the FORCE Fails You

Goldengate 12c Troubleshooting XAGENABLE

A performance Deep Dive into Tablespace Encryption

EBS Release 12 Certified with Safari 10 and MacOS Sierra 10.12

Oracle Database 12c (12.2.0.1.0) on VirtualBox

SQL Server:

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Experiments with MySQL 5.7’s Online Buffer Pool Resize

One of the interesting features introduced in MySQL 5.7 is that innodb_buffer_pool_size is a dynamic variable (since 5.7.5, to be more specific). Yet, past experience tells us that just because a variable is dynamic, it does not make it is safe to change it on the fly.

To find out how safe this new feature is, I measured throughput on a synthetic workload (sysbench 1.0 running the oltp script) as I made changes to this variable. In this post, I will show the results that came through.

 

The Environment

For my tests, I used a Google Cloud Compute instance of type n1-standard-4 (that is 4 vCPUs and 15 GB of memory) with 25 GB of persistent …

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Asynchronous Replication from MySQL Cluster

MySQL Cluster is a highly available, distributed, shared-nothing database with very interesting performance characteristics for some workloads. Among other features, it supports automatic sharding and allows us to bypass the SQL layer if we don’t need it, via the NDB API (which in my eyes, makes it one of the few transactional nosql databases out there).

In this post, I’ll describe how we can set up replication from MySQL Cluster into a standalone MySQL server using Innodb as the storage engine.

Introduction

There are a few reasons to set up replication between MySQL Cluster and a non-NDB based MySQL server. These reasons include (but are not limited to): the need …

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Log Buffer #507: A Carnival of the Vanities for DBAs

This Log Buffer edition covers Oracle, SQL Server and MySQL blog posts with a touch of Cloud.

Oracle:

Provisioning EBS on Oracle Cloud: Latest Enhancements

ORA-54002 when trying to create Virtual Column using REGEXP_REPLACE on Oracle 12cR2

Business rules, common sense and query performance

Problem with V$RECOVERY_AREA_USAGE view and FRA space not being reclaimed

Updated …

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