The MariaDB subquery cache feature added in MariaDB 5.3 is not widely known. Let’s see what it is and how it works.

What is a subquery cache?

The MariaDB subquery cache optimizes the execution of correlated subqueries. Correlated subqueries refer to a value from the parent query. For example:

SELECT id FROM product WHERE price NOT IN (SELECT MAX(price) FROM product GROUP BY category);

MariaDB only uses this optimization if the parent query is a SELECT, not an UPDATE or a DELETE. The subquery results get cached only for the duration of the parent query.

MariaDB added the subquery cache in v5.3. It is controlled by …

Thank you everyone who attended our Webinar on “Monyog v7.04 demonstration & Roadmap Update”.

During the webinar, Shree gave a complete walkthrough of the all new Monyog v7.04. He also shared the product roadmap along with the performance improvements for bigger deployments.

Here’s the complete video for all those who couldn’t attend the webinar.

We hope you found the webinar useful. We will be conducting more webinars in upcoming weeks. To keep yourself updated, subscribe to our blogs.

Download a free trial of Monyog here.

The post Highlights: Monyog v7.04 demonstration & Roadmap Update appeared first on Webyog Blog.

UPDATE: Some of the language in the original post was considered overly-critical of Oracle by some community members. This was not my intent, and I’ve modified the language to be less so. I’ve also changed term “synchronous” (which the use of is inaccurate and misleading) to “virtually synchronous.” This term is more accurate and already used by both technologies’ founders, and should be less misleading.

I also wanted to thank Jean-François Gagné for pointing out the incorrect sentence about multi-threaded slaves in Group Replication, which I also corrected accordingly.

In today’s blog post, I will briefly compare two major virtually synchronous replication technologies available today for MySQL.

More Than Asynchronous Replication

…

Sometimes MySQL surprises you in ways you would have never imagined.

Would you think that the order in which the indexes appear in a table matters?
It does. Mind you, not the order of the columns - the order of the indexes.
MySQL optimizer can, in specific circumstances, take different paths, sometimes with nefarious effects.


Please consider the following table:

CREATE TABLE `mypartitionedtable ` (
  `HASH_ID` char(64) NOT NULL,
  `RAW_DATA` mediumblob NOT NULL,
  `EXPIRE_DATE` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  KEY `EXPIRE_DATE_IX` (`EXPIRE_DATE`),
  KEY `HASH_ID_IX` (`HASH_ID`)
) ENGINE=TokuDB DEFAULT CHARSET=latin1 ROW_FORMAT=TOKUDB_UNCOMPRESSED
/*!50100 PARTITION BY RANGE (UNIX_TIMESTAMP(EXPIRE_DATE))
(PARTITION p2005 VALUES LESS THAN (1487847600) ENGINE = …

This post is a case study of a job I had to do in a legacy application, it doesn’t mean it will apply to you, but it might.

This is a table of contents:

• Performance
• Searching
• Converting to a JSON array
• 1st step: remove the leading commas
• 2nd step: add brackets to the string
• 3rd step: validate if the changes works
• Replacing 1st step and …

Percona announces the GA release of Percona XtraBackup 2.4.6 on February 22, 2017. You can download it from our download site and apt and yum repositories.

Percona XtraBackup enables MySQL backups without blocking user queries, making it ideal for companies with large data sets and mission-critical applications that cannot tolerate long periods of downtime. Offered free as an open source solution, Percona …

Percona announces the release of Percona XtraBackup 2.3.7 on February 22, 2017. Downloads are available from our download site or Percona Software Repositories.

Percona XtraBackup enables MySQL backups without blocking user queries, making it ideal for companies with large data sets and mission-critical applications that cannot tolerate long periods of downtime. Offered free as an open source solution, Percona XtraBackup drives down backup costs while providing unique features for MySQL backups.

This release is the …

Today i am going to share with you how to create CRUD Application with pagination using JQuery Ajax in Codeigniter 3CRUD is a basic step of any Core Language or framework CRUD stand for Create Read Update and Delete So in this post we will learn insert update delete in codeigniter using jquery

Today i am going to share with you how to create CRUD Application with pagination using JQuery Ajax in Codeigniter 3CRUD is a basic step of any Core Language or framework CRUD stand for Create Read Update and Delete So in this post we will learn insert update delete in codeigniter using jquery

Whenever we want a query’s results sorted, you may think of using the clause “order by.” You are correct: most of the time, MySQL will return the results in expected order with “order by.”

Be careful, though. Sometimes MySQL may return results in the non-deterministic order even with “order by.”

Indeed, if a query is ordered by a non-unique column, it may return results in an unexpected order. I tested the below example on MySQL 5.1.73, 5.5.54 and 5.6.19 and got the same result. However, when I applied the same example on MySQL 5.7.17, it returned the results in an unexpected order differently.

Follow me step-by-step and see how MySQL returns results in a non-deterministic order. Step 1-4 is for MySQL 5.1.73, 5.5.54 and 5.6.19, Step 5 is for MySQL 5.7.17. After the example, I will explain the reason behind this output.

Step 1. Create the table as …