Showing entries 71 to 80 of 36945
« 10 Newer Entries | 10 Older Entries »
Thoughts on Back Pressure

I watched the “Arista Networks 7500 Series Architecture” video again last night. I’ve embedded it below.

I think that was at least the third time I’ve seen that video. Even if you’re not a networking nerd, I suggest that you watch it at least once.

Packet Buffers

Most of the video is about packet buffers. Specifically, it’s about big buffers vs small buffers in switches. Switches have packet buffers to sustain bursts. If a switch’s buffers fill up, it’ll start dropping packets. There’s nothing else it can do.

Dropped packets are a scenario we can tolerate. Protocols like TCP have mechanisms to detect and work around dropped packets. An application running on top of TCP doesn’t really see this dropping and retransmission happen. All it sees is network I/O getting slower. Back pressure.

There’s an important slide that comes up at around 20:00. It’s about the distribution of …

[Read more]
Log Buffer #493: A Carnival of the Vanities for DBAs

This Log Buffer Edition covers various valuable blog posts from the fields of Oracle, SQL Server and MySQL.


Oracle Planning and Budgeting Cloud – Modern Learning at Its Best

ADF Regions and Shared Data Control Bindings Use Case

Oracle GROUP_ID Function with Examples

Integration Cloud Service (ICS) On-Premise Agent Installation by Greg Mally

A …

[Read more]
Changing the Tablespace Directory with pt-online-schema-change

In this blog, we’ll discuss changing the tablespace directory using pt-online-schema-change.

One of the most annoying situations in the life of a DBA is realizing that the disk where the datadir resides is running out of space. If you’re lucky enough to run over an LVM volume or a RAID (depending on the level, though), it is easy to add disk space. But what if you are not that lucky, and your datadir is running on a single disk? Not so funny!

That is the exact situation we recently faced with a customer, for both the master and slave server. When trying to figure out a solution we saw that:

  • There was enough space on a different partition within the same server.
  • The tables have their own tablespace (innodb_file_per_table = on)
  • The MySQL version was …
[Read more]
Open-sourcing Rocksplicator, a real-time RocksDB data replicator

Pinterest’s stateful online systems process tens of petabytes of data every day. As we build products and scale billions of Pins to 150 million people, we need new applications that work in a way where computation co-locates with data. That’s why we adopted RocksDB. It’s adaptable, supports basic and advanced database operations with high performance and meets the majority of requirements for building large-scale, production-strength distributed stateful services. Yet two critical pieces were missing for us: real-time data replication and cluster management for RocksDB-based stateful services. To fill this gap, we built a RocksDB replicator–Rocksplicator–a cluster management library, as well as tools for RocksDB-based stateful services. Today we’re open-sourcing the project on GitHub for all RocksDB users. 

Before we dive into Rocksplicator, …

[Read more]
Separation of Query Server and Data Server

In MySQL we have separated the Query Server and the Data Server
functionality. The Query Server is what takes care of handling the
SQL queries and maps those to lower layers call into the Data Server.
The API to the Data Server in MySQL is the storage engine API.

Almost all DBMS have a similar separation between Data Server and Query

When I performed my research work, that later led to development of
NDB Cluster, that is now MySQL Cluster, an important part of the
research was to handle the separation of the Data Server and
the Query Server.

As part of my research we looked deeply into the next generation mobile
networks and their use of network databases. From these studies it was
obvious that the traffic part of the applications almost always made very
simple queries, mostly key lookups and in some cases slightly more …

[Read more]
MySQL can be evil

Ok, maybe evil is too strong a word, but MySQL can certainly be deceiving.

MySQL can be evil

Ok, maybe evil is too strong a word, but MySQL can certainly be deceiving.

Orchestrator: Moving VIPs During Failover

In this post, I’ll discuss how to moving VIPs during a failover using Orchestrator.

In our previous post, we showed you how Orchestrator works. In this post, I am going to give you a proof-of-concept on how Orchestrator can move VIPs in case of failover. For this post, I’m assuming the Orchestrator is already installed and able to manage the topology.


Orchestrator is a topology manager. Nothing less nothing more. In the case of failover, it will reorganize the topology, promote a new master and connect the slaves to it. But it won’t do any DNS changes, and it won’t move VIPs (or anything else).

However, Orchestrator supports hooks. Hooks are external scripts …

[Read more]
FromDual.en: FromDual Performance Monitor for MySQL and MariaDB 1.0.0 has been released

FromDual has the pleasure to announce the release of the new version 1.0.0 of its popular Database Performance Monitor for MySQL, MariaDB, Galera Cluster and Percona Server fpmmm.

You can download fpmmm from here.

In the inconceivable case that you find a bug in fpmmm please report it to our Bug-tracker.

Any feedback, statements and testimonials are welcome as well! Please send them to

This release contains various bug fixes and improvements. Further significant functionality has changed and improved. So please read carefully...

Changes in fpmmm v1.0.0

fpmmm agent

[Read more]
MySQL Replication: All the Severalnines Resources

As many of you will know, MySQL Replication has become an instrumental part of scale-out architectures in LAMP environments. MySQL offers plenty of solutions when there is a need to scale out, the most common being to add read replicas. The major bottleneck for our data is generally not so much oriented around writing our data but more around reading it back. Therefore the easiest way to scale MySQL is to add replicas for reading.

We’ve produced a number of resources during the course of this year aimed at helping users to get started with MySQL Replication and/or get more out of their existing setups.

We’ve summarised these resources here in a handy overview, so that you can pick and chose the ones that might be the most relevant to you.

Do check them out and let us know your feedback!

The White Papers The MySQL© Replication Blueprint by Severalnines

This is a great resource for anyone wanting to …

[Read more]
Showing entries 71 to 80 of 36945
« 10 Newer Entries | 10 Older Entries »