Whenever you need to use GROUPCONCAT with differente separatorI mean default separator is But you want to change etc as you want then you have to use use SEPARATOR keyword in GROUPCONCAT If you are working on laravel then you have to also use DBraw for write GROUPCONCA

Data corruption! It can happen. Maybe because of a bug or storage problem that you didn’t expect, or MySQL crashes when a page checksum’s result is different from what it expected. Either way, corrupted data can and does occur. What do you do then?

Let’s look at the following example and see what can be done when you face this situation.

We have some valuable data:

> select * from t limit 4;
+---+--------+
| i | c      |
+---+--------+
| 1 | Miguel |
| 2 | Angel  |
| 3 | Miguel |
| 4 | Angel  |
+---+--------+
> select count(*) from t;
+----------+
| count(*) |
+----------+
|  2097152 |
+----------+

One day the query you usually run fails and your application stops working. Even worse, it causes the crash already mentioned:

> select * from t where i=2097151;
ERROR 2006 (HY000): MySQL server has gone away

Usually this is the point when panic starts. The error log shows: …

The “CAP theorem” is often presented as something deep and hard to understand, and then discussed in confusing terms, to make sure it is hard to understand.  Really, it’s almost common sense – eg, if you have a partition, you have to give up availability or consistency.  Anyone familiar with, eg, drbd/split-brain/STONITH knows all about this.

I was reading a bit about it (again), and I use the sneer quotes on “theorem” because I think that the “proof” is really just adding some mathematical terms to the mix and restating it – QED.  (If this is considered the proof – “Brewer’s Conjecture and the Feasibility of Consistent, Available, Partition-Tolerant Web Services” .)  “Conjecture” doesn’t seem right either.  Maybe CAP observation?

It’s refreshing to …

The details and examples of Schemaless triggers, a key feature of the datastore that’s kept Uber Engineering scaling since October 2014. This is the third installment of a three-part series on Schemaless; the first part is a design overview…

The post Using Triggers On Schemaless, Uber Engineering’s Datastore Using MySQL appeared first on Uber Engineering Blog.

The newest release of the MySQL Connector/Arduino library release-1.1 alpha is available for download. This new version represents a major step forward for the library in ease of use. Here are just a few of the important changes in this release.

• Added to Library Manager : yes, you can download and install the library from the Arduino IDE now. Just open the Library Manager and search for "MySQL".
• More Example Sketches : there are many more example sketches of how to use the new library from basic connections to complex queries and more! 
• Redesigned Classes : the library has been redesigned with new classes making it much easier to use a wider variety of shields and modules. Now, you pass in the Client class for your shield and so long as it adheres to the Ethernet.Client primitive, you can use any library to initiate …

With MySQL 5.7, our goal is to be secure by default. This means that without having to change configuration settings or perform any additional steps, your fresh installation should be safe for production use.

As part of this security initiative, MySQL 5.7 shipped with a new feature where user accounts will be disabled if the password has not been changed in a number of days.…

We have discussed about the conceptual data model, logical data model, normalization and denormalization techniques and we discussed about installing and running up with MySQL community server.  What will be next? Once we build the data model and decided the database server, the next process will be start developing the physical database. What is needed to develop physical database? We need a common language to communicate with both the developer and database server. Here, comes the structure query language. So in this post we are going to see about the …

This is a followup to my previous post Apache Spark with Air ontime performance data.

To recap an interesting point in that post: when using 48 cores with the server, the result was worse than with 12 cores. I wanted to understand the reason is was true, so I started digging. My primary suspicion was that Java (I never trust Java) was not good dealing with 100GB of memory.

There are few links pointing to the potential issues with a huge HEAP:

http://stackoverflow.com/questions/214362/java-very-large-heap-sizes
…

This Log Buffer Edition begins with some great blog posts from Oracle, goes through SQL Server and then ends with MySQL.

Oracle:

• Ruby-oci8 is a ruby interface for an Oracle Database.
• Another python graph – one wait event.
• This article compares FBL and HDL – two of the commonly used data loading tools in Fusion HCM to highlight key differences and similarities.
• Better Data Modeling: Customizing Oracle …

How Uber’s infrastructure works with Schemaless, the datastore using MySQL that’s kept Uber Engineering scaling since October 2014. This is part two of a three-part series on Schemaless; part one is on designing Schemaless.

In Project Mezzanine: …

The post The Architecture of Schemaless, Uber Engineering’s Trip Datastore Using MySQL appeared first on Uber Engineering Blog.