Scenarios:-

I met with requirements where database has to generate business error if users are try to fetch  more than 1000 records from table.

Solutions:-
In MySQL to handle business error , we have to implement SIGNAL/RESIGNAL in code business logic.
This enable us to any time we can break our execution of code flow & generate Business Error as per our Requirements. 
There is no privileges are required to execute SIGNAL/RESIGNAL statement.
To handle normal error block, we have DECLARE CONTINUE/EXIT HANDLER ... Block , what it does is when ever encountered error during code execution HANDLER Block triggered and manage code execution inside of it. it is more flexiable because developers gets flexibility to write multi-statements inside HANDLER blocks.
More Info: https://dev.mysql.com/doc/refman/8.0/en/resignal.html
      …

The old adage that time is money does not give any hints about buying more time. A MySQL Enterprise subscription does allow you to purchase time. Your technical staff has to do more with less time than ever before and operational delays add up extremely quickly.  Having the right tools when things go critical means staff can do what they need to do, when they need to do it.

So how does MySQL Enterprise Edition buy you more time?

When things inevitably go wrong, searching for free answers to problems on web sites with many dubious or flat out wrong solutions is a waste of precious time.  Informational websites like are fine sources of general information for researching technical issues but not when mission critical services are degraded or down.  An online recommendation to do what very large Enterprise Company does may not make sense for your company if you are not …

JSON has proven to be a very import data format with immense popularity. A good part of my time for the last two or so years has been dedicated to this area and I even wrote a book on the subject.  This is a comparison of the implementations of handling JSON data in MySQL and MariaDB. I had requests from the community and customers for this evaluation.


JSON Data Types Are Not All Equal
MySQL added a JSON data type in version 5.7 and it has proven to be very popular.  MariaDB has  JSON support  version 10.0.16 but is actually an alias to a longtext data type so that statement based replication from MySQL to MariaDB is possible.

MySQL stores  JSON documents are …

MySQL Replication Data Recovery using 'mysqlbinlog' - Part II

The previous post (PART-I)
http://mysqlhk.blogspot.com/2018/10/mysql-replication-recovery-from-binlog.html

It describes the Replication Recovery from binlog by using those binlog files to be treated as Relay Log.  The Relay Log mechanism when the server is startup, the recovery is the SQL_THREAD applier to apply data to the database.    Check on the PART-I post for details.

Part II is about using the MySQL utility "mysqlbinlog" to dump the content from binlog files and apply the SQL to the Database.

Documentation
https://dev.mysql.com/doc/refman/8.0/en/mysqlbinlog.html
https://dev.mysql.com/doc/refman/8.0/en/point-in-time-recovery.html

The following sections describe the tutorial for Replication Data Recovery using 'mysqlbinlog'. 

The tutorial …

MySQL 8.0 Code Contributions (Shutterstock)

An Oracle engineer thanked two Percona engineers by name, along with engineers from Facebook and elsewhere, for their recent MySQL 8.0 source code contributions. Oracle incorporated their work into its latest MySQL production release (8.0.13).

Percona’s Zsolt Parragi authored a patch for a rare replication bug that left locked mutexes in production builds following debug crashes (bug # …

Somebody on Freenode wanted this:

   Source            Result
+----+------+    +----+------+
| id | x    |    | id | c    |
+----+------+    +----+------+
|  1 |    1 |    |  1 |    2 |
|  2 |    1 |    |  2 |    2 |
|  3 | NULL |    |  3 | NULL |
|  4 | NULL | -> |  4 | NULL |
|  5 |    1 |    |  5 |    1 |
|  6 | NULL |    |  6 | NULL |
|  7 |    1 |    |  7 |    3 |
|  9 |    1 |    |  9 |    3 |
| 10 |    1 |    | 10 |    3 |
+----+------+    +----+------+

The result uses the NULL values in x as boundaries of windows, and counts the number of rows within each window. I don’t know why anyone wants such a thing; it is not ours to reason why…

Anyway, the point is that you can use arbitrary expressions, even subqueries, to define your window partitions.

SELECT 
    id, 
    -- Count of rows in windows bound by NULL values in x
    IF(
      x IS NULL, 
      NULL, 
      COUNT(*) OVER (PARTITION BY (
        -- …

If you’re here, that probably means you’re about to acquire some sensitive data to take care of. Or that you’ve already acquired it and are protecting it, and you want to see how MySQL Enterprise Data Masking and De-Identification features can help you do it in an easier, better and more efficient manner.…

As promised, here are slides about MySQL 8.0 Performance from my talks at Oracle Open World 2018 and Percona LIVE Europe 2018 -- all is combined into a single PDF file to give you an overall summary about what we already completed, where we're going in the next updates within our "continuous release", and what kind of performance issues we're digging right now.. ;-))
Also, I'd like to say that both Conferences were simply awesome, and it's great to see a constantly growing level of skills of all MySQL Users attending these Conferences ! -- hope you'll have even more fun with MySQL 8.0 now ;-))

Welcome to Wednesday at Percona Live Europe 2018! Today is the final day! Check out all of the excellent sessions to attend.

Please see the important updates below.

Download the conference App

If you haven’t already downloaded the app, go to the app store and download the official Percona Live App! You can view the schedule, be alerted for any important updates, create your own personalized schedule, rate the talks and interact with fellow attendees.

For Apple: Download here
For Android:  …

Common Table Expressions (CTEs) are a very useful tool and frankly a big improvement on sub-queries.  But there are differences in how they are implemented in MySQL and MariaDB.  That  is not too surprising since the code fork many years ago. Different engineers implementing the same idea will have different approaches (and sometimes results). But differences in implementation are often important and, in this case, shockingly different.

Jesper Wisborg Krogh at Oracle OpenWorld and CodeOne gave a series of presentations and hands on labs that were excellent. He is an amazing Support Engineer and a great presenter of material at conferences.  In the lab for Common Table Expressions he did point out to me an interesting problem in MariaDB's implementation of CTEs. 

The Problem In a Nutshell
On the PostgreSQL Wiki, there is a
an SQL query (requires PostgreSQL 8.4 or MySQL 8.0) that …