The latest from the MySQL community

MariaDB 10.0.16 was recently released (~1.5 months ago on 1/27/2015 – sorry for the delay on my end – I was just extra busy in my spare time recently), and is available for download here:

https://downloads.mariadb.org/mariadb/10.0.16/

This is the seventh GA release of MariaDB 10.0, and 17th overall release of MariaDB 10.0.

For the most part, there are not a whole lot of changes to report for this release, but there are 2 enhancements of note – one being the JSON table type (still *experimental*) and the other a new variable to aid with index statistics calculations on large tables, as well as some security fixes.

Here are the main items of note:

1. Updates to the CONNECT handler (supporting the …

One of the great features of Shard-Query is the ability to use MySQL proxy to access resultsets transparently. While this is a great tool, many people have expressed reservations about using MySQL Proxy, an alpha component in their production environment.

I recognize that this is a valid concern, and have implemented an alternate method of retrieving resultsets directly in the MySQL client, without using a proxy. This means that any node can easily act as the “head” node without any extra daemon, instead of having to run many proxies.

The sq_helper() routine has been checked into the git repository and is available now.

The function takes a few parameters:

• sql to run
• shard-query schema name (empty string or null for default schema)
• schema to store temp table in
• temp table name (where results are sent to)
• return result (boolean, 1 returns …

MySQL meets NoSQL with JSON UDF

I recently got back from FOSDEM, in Brussels, Belgium. While I was there I got to see a great talk by Sveta Smirnova, about her MySQL 5.7 Labs release JSON UDF functions. It is important to note that while the UDF come in a 5.7 release it is absolutely possible to compile and use the UDF with earlier versions of MySQL because the UDF interface has not changed for a long time. However, the UDF should still be considered alpha/preview level of quality and should not be used in production yet! For this example I am using Percona Server 5.6 with the UDF.

That being said, the proof-of-concept that I’m about to present here uses only one JSON function (JSON_EXTRACT) and it has worked well enough in my testing to present my idea here. The JSON functions will probably be GA sometime soon anyway, and this is a useful test of the JSON_EXTRACT function. …

New version of JSON UDF functions has been just released. This is maintenance release which only contains fix for 4 bugs:

74090/19821398 `INSTALL_JSONUDFS` ISSUES A WARNING DUE TO TRUNCATION OF `VERSION_COMPILE_OS`
74091/19692634 `JSON_DEEP_MERGE`: DEEP CRASH IN `MERGE_TREE`
74092/19692628 CRASH WITH SECOND-HAND NULL IN PARAMETERS
74097/19693198 `CREATE_NEW_VALUE`: STACK BUFFER OVERFLOW, %LLD CAN'T FIT IN CHAR[20]

Also 0.3 branch becomes stable branch and no new features will be pushed to this branch in future. Previous stable branch (0.2) removed from MySQL Labs website.

…

Today new version of JSON UDF functions: 0.3.2 was released. This is development release which contains new functionality. You can download functions from the MySQL Labs website.

What is new?

New function `JSON_COUNT` added. This function returns number of children of the key path specified. If no key path specified, number of children of the root element is returned. Bug #70580/17584692 ADD FUNCTION `JSON_COUNT` TO COUNT SIZE OF JSON DOCUMENT

mysql> select json_count('{"MySQL Central": ["conference", 2014]}') as 'root count',
    ­> json_count('{"MySQL Central": ["conference", 2014]}', 'MySQL Central') as 'first element count'\G     
                                                   
************************ 1. row ************************
         root count: 1
first element count: 2
1 row in set …

August 15, 2014 By Severalnines

We're looking for an energetic and talented web developer to join our small but agile web team. This position is full-time and pay is negotiable. The hours are flexible and work can be done remotely.

Severalnines is a self-funded startup with a dozen employees; headquartered in Stockholm, Sweden and with a globally distributed, home-office based team. We provide automation and management software for database clusters. Our ClusterControl product is the leading management application for database clusters and is used by thousands of companies.

We were founded in 2010 and launched our product that same year, so you’ll be …

I got an interesting question about EXPLAIN and the range access method recently. The person had a query that could be written either with a BETWEEN predicate or an IN predicate, something similar to this:

mysql> EXPLAIN SELECT * 
    -> FROM orders WHERE customer_id BETWEEN 7 AND 10 AND value > 500;
+----+-------------+--------+-------+----------+----------+------+------
| id | select_type | table  | type  | key      | key_len  | rows | Extra
+----+-------------+--------+-------+----------+----------+------+------
|  1 | SIMPLE      | orders | range | cust_val | 10       |   91 |  ...
+----+-------------+--------+-------+----------+----------+------+------

mysql> EXPLAIN SELECT * 
    -> FROM orders WHERE customer_id IN (7,8,9,10) AND value > 500;
+----+-------------+--------+-------+----------+----------+------+------
| id | select_type | table  | type  | key      | key_len  | rows …

Today new version of JSON UDF functions: 0.3.1 was released. This is development release which contains new functionality. You can download functions from the MySQL Labs website.

What is new?

Default value for compile option `WITH_PCRE` now is `bundled` independently from the
platform (Bug #71265/18081332 Library name mismatch for PCRE on Ubuntu)

New values, passed to functions `JSON_APPEND`, `JSON_REPLACE`, `JSON_SET` as numbers, empty strings or `NULL`s are converted to JSON objects. Objects, passed as strings are not converted: you are still responsible to put quotes around string values. Also these functions check if element which needs to be inserted is valid JSON value. (Bug #70394/17491708 MySQL JSON UDFs: …

When I presented JSON UDF functions at MySQL Connect last year attendees asked me to implement few features. I quickly wrote their wishes in my notepad. I also created feature requests at bugs.mysql.com  when I was home.

During following months I fixed bugs in the functions and implemented feature requests, including those which I got from MySQL Connect. I started from most important and affecting users, such as wrong results bugs of features for which I got more than one request.

But today all such requests finished and I am working on bug #70580  This feature request says: "Add function JSON_COUNT which will go through the JSON document and count number of childs of the root element." Well, I wrote it myself, but I don't exactly remember if the user wanted to know depth of the JSON …

New version of JSON UDF functions 0.2.2 have been just released. It is last maintenance release of 0.2 series. However it contains two new features:

JSON_VALID now accepts array as a root element of the JSON document (Bug#70567/17583282)

JSON functions can now be installed and uninstalled using a script (Bug#71263/18022788 Easy installation sql script).

This feature is Community contribution. Thank you, Daniel van Eeden!

This release also contains following bug fixes:

71050/17882710 json_extract returning same column twice if key names are not fully distinct. (Fixed for JSON_EXTRACT, JSON_CONTAINS_KEY, JSON_APPEND, JSON_REMOVE, JSON_REPLACE, JSON_SET) …