The Theory

Generated Columns is a feature released on MySQL 5.7. They can be used during CREATE TABLE or ALTER TABLE statements. It is a way of storing data without actually sending it through the INSERT or UPDATE clauses in SQL. The database resolves what the data will be.

There are two types of Generated Columns: Virtual and Stored. They work with:

• mathematical expressions (product_price * quantity)
• built-in functions (RIGHT(), CONCAT(), FROM_UNIXTIME(), JSON_EXTRACT())
• literals (“2”, “new”, 0)

Besides that, they can be indexed but they don’t allow …

This blog updates Stephane Combaudon’s blog on MySQL performance tuning, and covers MySQL 5.7 performance tuning immediately after installation.

A few years ago, Stephane Combaudon wrote a blog post on Ten MySQL performance tuning settings after installation that covers the (now) older versions of MySQL: 5.1, 5.5 and 5.6. In this post, I will look into what to tune in MySQL 5.7 (with a focus on InnoDB).

The good news is that MySQL 5.7 has significantly better default values. Morgan Tocker created a page with a complete list of features in MySQL 5.7, and is a great reference point. For example, the …

General query logs and slow query logs remain one of the most popular sources of auditing and diagnostic information in MySQL databases. Customers often ask about the cost of general and slow query logging so I went googling for existing research I could point them to. The data I found was not quite what I hoped for, which is why I decided to do some more testing.

Introduction Logging overhead is an obvious thing and it has been the topic of many blog posts before this one. Sure enough, my Google search returned multiple articles, however I wasn't fully satisfied the findings.
Perhaps the topic is so obvious that DBAs don't revisit it very often. In any case, most of the articles I found were several years old and that presents a few issues:

1. Most of the tests were run on MySQL 5.0 or 5.1.
2. Database hardware isn't what it used to be, which changes the perspective on database performance bottlenecks. …

Optimiser is the brain of the RDBMS. Optimiser decides the right access method , algorithms , join order and right index to be used for better execution of the query. This blog is made to shed some lights on Cost based optimiser in MySQL 5.7. The cost or statistics are stored in the data dictionary .

What is cost-based optimization ?

• The cost model is based on estimates of cost various operations occur during query execution.

• The optimizer has a set of default “cost constants” it will make decision on execution plans.

• In MySQL 5.7, the optimizer has addition a database of cost estimates to use during the execution plan.

• These cost estimates are stored in server_cost & engine_cost tables in MySQL schema. For more details Cost Model

MySQL …

The MySQL keynote at Oracle Open World 2016 announced the immediate availability of the MySQL Cloud Service, part of the larger Oracle Cloud offering. You can evaluate this now with a trial copy at cloud.oracle.com/mysql. MySQL server product manager Morgan Tocker gave two presentations at the event including a deep dive session.

This is the first release of the MySQL cloud service. As with all first releases there are some highlights and some pipeline features. All major cloud providers have MySQL offerings. AWS RDS (traditional, MAZ and Aurora) GCP Cloud SQL and Azure …

This blog post explains benefits, features and limitations of the improved semi-sync replication in MySQL 5.7

The post Improved Semi-Sync Replication in MySQL 5.7 appeared first on Datavail.

Disclaimer: this post takes into consideration that strict mode is enabled on the server

VARCHAR  and  CHAR  are used to store strings. VARCHAR stores varying length and CHAR always use the same exact size no matter the size of the string. For example, CHAR(4) will always store 4 bytes, whereas VARCHAR(4) will store up to 5 bytes. See documentation.

When we create a table like this one:

We put inside the parentheses the length of the field in characters for the VARCHAR field. However, the maximum size in bytes of the field will depend on the CHARSET and COLLATION of the table. You can also specify a different collation for a column.

For instance:

• latin1: 1 to 2 bytes per …

This blog post focuses on MySQL 5.7's newly improved features of security validation and password expiration.

The post Security Validation and Password Expiration in MySQL 5.7 appeared first on Datavail.

Recently, I was discussing with one of my colleagues about how insert statement performs for MySQL partitioned tables. General prediction is that it should be slower than for non-partitioned tables, but how much that we didn’t know. So, I thought let’s test with different types of partitions (i.e range, list and hash) and also with different number of partitions and check how’s performance. As people says, MySQL 5.7 is must faster than old one, so I also tested partitions with it.

So, I took simple table with 3.2M records on Centos 6.7 VM (4 core with 2GB RAM) with default my.cnf settings and then created tables for range, list and hash partitioning with 5,25,50 and 100 partitions. i.e with 5 partition (range and list), the table structures were like

CREATE TABLE emp_range_5(
 id int,
 fname varchar (30),
 lname varchar (30),
 hired_date date not null,
 separated_date date not null,
 job_code int,
 store_id int
 ) …

In a previous post, I presented an Unexpected Memory Consumption for Bulk Index Creation in InnoDB.  This was triggered by an increased innodb_sort_buffer_size and as stated in another post: "the sorting algorithm does not scale well with large sort buffers".  In this post, I will present why it does not scale well and I will suggest solutions.

This post also answers feedback request for the