In my previous blog post, I showed an example of how the MySQL Optimizer found a better join order by taking into account the filtering effects of conditions. I also explained that for non-indexed columns the filtering estimate is just a guess, and that there is a risk for non-optimal query plans if the guess is off.

We have received a few bug reports on performance regressions when upgrading from 5.6 to 5.7 that are caused by the optimizer overestimating the filtering effect. In most cases, the cause of the regression is inaccurate filtering estimates for equality conditions on non-indexed columns with low cardinality. In this blog post, I will discuss three ways to handle such regressions:

1. Create an index
2. Use an optimizer hint to change the join order
3. Disable condition filtering
…

  When you see the above error , first thing come into mind is  Is our tnsnames.ora file is exist , if its there used connection string is there If you have it correctly and still issue is persist .. Then whats happens everything is good  1.First thing you have to check if tnsnames is fine sqlldr scott/HD@y45Hhds@orcl control=E:\test\table.ctl log=E:\test\table.log Check if you have password having '@' symbol 2.Then change it as below , you will be able to load the millions of files into oracle table  sqlldr scott/\"HD@y45Hhds\"@orcl control=E:\test\table.ctl log=E:\test\table.log Make it useful ..

Welcome to another post in the series of Percona Live featured session blogs! In these blogs, we’ll highlight some of the session speakers that will be at this year’s Percona Live conference. We’ll also discuss how these sessions can help you improve your database environment. Make sure to read to the end to get a special Percona Live 2017 registration bonus!

In this Percona Live featured session, we’ll meet Luís Soares, Principal Software Engineer at Oracle. His session is The New MySQL Replication Features in MySQL 8 (with fellow presenter Lars Thalmann, Development Director at Oracle). The most popular high availability …

ProxySQL is the leader in proxy and load balancing solution for MySQL. It has great features like query caching, multiplexing, mirroring, read/write splitting, routing, etc… The latest enhancement in ProxySQL is the native support of MySQL Group Replication. No more need to use an external script within the scheduler like I explained in this previous post.

This implementation supports Groups in Single-Primary and in Multi-Primary mode. It is even possible to setup a Multi-Primary Group but dedicate writes on only one member.

René, the main developer of ProxySQL, went even further. For example in a 7 nodes clusters (Group …

In this blog post, we’ll look at how to run Percona XtraDB Cluster on Windows using Docker.

This is a follow-up to my previous post on Percona XtraBackup on Windows. The fact is that with Docker you can now run a variety of software applications on Windows that previously were available only for Linux platforms.

We can run (to evaluate and for testing purposes) several nodes of Percona XtraDB Cluster on a single Windows box.

The steps for this are:

1. Setup Docker on the Windows box.
   …

For years, MySQL replication used to be based on binary log events - all a slave knew was the exact event and the exact position it just read from the master. Any single transaction from a master may have ended in different binary logs, and in different positions in these logs. It was a simple solution that came with limitations - more complex topology changes could require an admin to stop replication on the hosts involved. Or these changes could cause some other issues, e.g., a slave couldn’t be moved down the replication chain without time-consuming rebuild process (we couldn’t easily change replication from A -> B -> C to A -> C -> B without stopping replication on both B and C). We’ve all had to work around these limitations while dreaming about a global transaction identifier.

GTID was introduced along with MySQL 5.6, and brought along some major changes in the way MySQL operates. First of all, every transaction has …

The video below details the features and functions that are available in ClusterControl for MySQL Replication.  Included in the video are…

• How to Deploy Master-Slave Replication
• How to Deploy Multi-Master Replication
• MySQL Replication overview including metrics
• Individual Node overview & management
• Backup management from Slaves or Masters
• Adding Nodes
• Adding Load Balancers

ClusterControl Single Console for Your Entire Database Infrastructure Find out what else is new in ClusterControl Install ClusterControl for FREE ClusterControl for MySQL Replication

…

As you know, MySQL Group Replication runs by default in single primary mode.

mysql2 mysql> show global variables like 'group_replication_single_primary_mode';
+---------------------------------------+-------+
| Variable_name                         | Value |
+---------------------------------------+-------+
| group_replication_single_primary_mode | ON    |
+---------------------------------------+-------+

But how can we easily find which member of the group is the Primary-Master ?

Of course you could check which one is not in read_only:

mysql2 mysql> select @@read_only;
+-------------+
| @@read_only |
+-------------+
|           1 |
+-------------+

But then you need to perform this on all the nodes one by one until you find the right one.

The primary …

In this blog post, I’ll take a look at the performance of the Samsung 960 Pro SSD NVME.

First, I know the Samsung 960 Pro is a consumer SSD NVME drive, not intended for sustained data center workloads. But the AnandTech review looked good enough that I decided to take it for a test spin to see if it would work well with MySQL benchmarks.

Before that, I decided to do a simple sysbench file IO test to see how the drives handled sustained workloads, and if it would start acting up.

My expectation for a consumer SSD drive is that its write consistency will suffer. Many of those drives can sustain high bursts for short periods of time but have to slow down to keep up with write leveling (and other …

MySQL Connector/Python 2.2.3 M4 is the fourth development release of the MySQL Connector Python 2.2 series. This series adds support for the new X DevAPI. The X DevAPI enables application developers to write code that combines the strengths of the relational and document models using a modern, NoSQL-like syntax that does not assume previous experience writing traditional SQL.

To learn more about how to write applications using the X DevAPI, see http://dev.mysql.com/doc/x-devapi-userguide/en/. For more information about how the X DevAPI is implemented in MySQL Connector/Python, and its usage, see http://dev.mysql.com/doc/dev/connector-python.

Please note that the X DevAPI requires MySQL Server version 5.7.12 or higher with the X Plugin enabled. For general …