The latest from the MySQL community

The previous post in the EXPLAIN FORMAT=JSON is Cool! series showed an example of the query

select dept_name from departments where dept_no in (select dept_no from dept_manager where to_date is not null)

, where the subquery was materialized into a temporary table and then joined with the outer query. This is known as a semi-join optimization. But what happens if we turn off this optimization?

EXPLAIN FORMAT=JSON

 can help us with this investigation too. …

Naturally, I ran into this problem in the middle of the night when the client was asleep and I had no access to the Magento administrative interface. The short story is that after running a re-index of the site, the home page began returning a 404 erro...

We could use inotify-tools to monitor file or directory IO state

yum install inotify-tools

#inotifywait -m /storage/sas/mysql3306/data/diablo_im/#sql-ib4747-2643139248.ibd

Setting up watches.                                                                
Watches established.                                                               
/storage/sas/mysql3306/data/diablo_im/#sql-ib4747-2643139248.ibd MODIFY            
/storage/sas/mysql3306/data/diablo_im/#sql-ib4747-2643139248.ibd MODIFY            
/storage/sas/mysql3306/data/diablo_im/#sql-ib4747-2643139248.ibd MODIFY            
/storage/sas/mysql3306/data/diablo_im/#sql-ib4747-2643139248.ibd MODIFY            
/storage/sas/mysql3306/data/diablo_im/#sql-ib4747-2643139248.ibd MODIFY            
/storage/sas/mysql3306/data/diablo_im/#sql-ib4747-2643139248.ibd MODIFY …

The source of this post is in this gist on nbviewer.

After reading about the difference between MySQL Connector/Python and MySQLdb on this blog post I wondered how the C Extension option in Connector/Python would perform.

If you want to run the code yourself you'll need: Jupyter/IPython, Python 3, Requests, MySQLdb, Connector/Python, Matplotlib, Pandas and MySQL.

In [1]:

%matplotlib notebook

In [2]:

import random
import gzip
import time

import pandas as pd
import matplotlib.pyplot as plt
import requests
import mysql.connector
import MySQLdb
for imp in [mysql.connector, MySQLdb]:
    print('Using {imp} {version}'.format(imp=imp.__name__, version=imp.__version__))
print('C Extension for …

When trying out new software there are many other questions you may ask and one of those is going to be the one above. The answer requires you to have built your software to capture and record low level database metrics and often the focus of application developers is slightly different: they focus on how … Continue reading Is MySQL X faster than MySQL Y? – Ask queryprofiler

The post Is MySQL X faster than MySQL Y? – Ask queryprofiler first appeared on Simon J Mudd's Blog.

Usually when one says “SSL” or “TLS” it means not a specific protocol but a family of protocols. Wikipedia article has the details, but in short — SSL 2.0 and SSL 3.0 are deprecated and should not be used anymore (the well-known POODLE vulnerability exploits the flaw in SSL 3.0). TLS 1.0 is sixteen years […]

The post The State of SSL in MariaDB appeared first on MariaDB.org.

The MariaDB project is pleased to announce the immediate availability of MariaDB 10.1.10, MariaDB Galera Cluster 5.5.47, and MariaDB Galera Cluster 10.0.23. See the release notes and changelogs for details on each release. Download MariaDB 10.1.10 Release Notes Changelog What is MariaDB 10.1? MariaDB APT and YUM Repository Configuration Generator Download MariaDB Galera Cluster 5.5.47 […]

The post MariaDB 10.1.10 and MariaDB Galera Cluster 5.5.47 and 10.0.23 now available appeared first on MariaDB.org.

We recently released the GA version of Percona Server for MongoDB, which comes with a variety of storage engines: RocksDB, PerconaFT and WiredTiger.

Both RocksDB and PerconaFT are write-optimized engines, so I wanted to compare all engines in a workload oriented to data ingestions.

For a benchmark I used iiBench-mongo (https://github.com/mdcallag/iibench-mongodb), and I inserted one billion (bln) rows into a collection with three indexes. Inserts were done in ten parallel threads.

For memory limits, I used a 10GB as the cache size, with a total limit of 20GB available for the mongod process, …

Many thanks to everyone who took the time yesterday to participate in our last webinar of 2015! Here are the recording of the session as well as the slides that were used by our colleague Art van Scheppingen, Senior Support Engineer, on the topic of Polyglot Persistence for the MongoDB, MySQL & PostgreSQL DBA.

Webinar Replay:

Webinar Slides:

Agenda

During this webinar, Art discussed the four major operational challenges for MySQL, MongoDB & PostgreSQL:

• Deployment
• Management
• Monitoring
• Scaling
• And how to deal with them

And demonstrated, using ClusterControl, how Polyglot Persistence for datastores can be managed from one central control centre. To find out more, feel free to contact us.

…

EXPLAIN FORMAT=JSON

The regular

EXPLAIN

 command already provides some information about subquery optimization. For example, you can find out if the subquery is dependent or not, and (since version 5.6) if it was materialized:

mysql> explain select dept_name from departments where dept_no in (select dept_no from dept_manager where to_date is not null)G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: departments
   partitions: NULL
         type: index
possible_keys: PRIMARY
          key: dept_name
      key_len: 42
          ref: NULL
         rows: 9
     filtered: 100.00
        Extra: Using where; Using index
*************************** 2. row ***************************
           id: 1
  select_type: SIMPLE
        table: …