The latest from the MySQL community

The MySQL Utilities Team is pleased to announce the latest GA release of
MySQL Utilities. This release marks a milestone of concentrated effort to
expand the use of utilities in more diverse installations through improved
robustness, error handling, and quality.

Many Improvements
There are number such enhancements in this release. In this post we will
highlight a few of the more significant improvements.

• (new utility) MySQL .frm Reader (mysqlfrm) - read .frm files and generate CREATE statements with or without a server connection.
• (revised) improved documentation including a section on example administrative tasks - see http://dev.mysql.com/doc/workbench/en/mysql-utilities.html
• MySQL Utilities is packaged for .msi, .rpl, .deb platforms and source .tar/.zip
…

In my recent SQL work for a large Swiss bank, I have maintained nested database view monsters whose unnested SQL code amounted up to 5k lines of code, joining the same table over and over again in separate subselects combined via UNION operations. This monster performed in way under 50ms, no matter how we queried … Continue reading The Myth About Slow SQL JOIN Operations →

I’ll be joining Percona for a free day of MySQL education and insight at their upcoming Percona University Washington DC event on September 12th. My topic is accessing MySQL from Google’s Go programming language. I’ve learned a lot about this over the past year or so, and hopefully I can help you get a quick-start.

If you’re not familiar with Go, it’s the darling of the Hacker News crowd these days. Anything with “Go” in its title gets to the front page for at least a little while! Go is a great systems programming language. It’s safe to say I’ve fallen in love with it, and it’s now my favorite programming language of all those I’ve used over my entire career. I chose it because it’s ideally suited for VividCortex’s agent programs (zero dependencies, compiled, lightweight, high performance, robust, makes concurrency …

Over time, some options have crept into the MySQL server which are comma separated lists of options. These include SQL_MODE, optimizer_switch, optimizer_trace and a few other variables.

Optimizer_switch is particularly problematic to work with as it contains many options and is hard to interpret. This is what you usually see when you examine optimizer_switch:

index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,engine_condition_pushdown=on,index_condition_pushdown=on,mrr=on,mrr_cost_based=on,block_nested_loop=on,batched_key_access=off,materialization=on,semijoin=on,loosescan=on,firstmatch=on,subquery_materialization_cost_based=on,use_index_extensions=on

As you can see, seeing which option is on or off is rather difficult. You can use the REPLACE function to make this easier:

mysql> select replace(@@optimizer_switch, ',','\n')\G …

Over time, some options have crept into the MySQL server which are comma separated lists of options. These include SQL_MODE, optimizer_switch, optimizer_trace and a few other variables.

Optimizer_switch is particularly problematic to work with as it contains many options and is hard to interpret. This is what you usually see when you examine optimizer_switch:

index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,engine_condition_pushdown=on,index_condition_pushdown=on,mrr=on,mrr_cost_based=on,block_nested_loop=on,batched_key_access=off,materialization=on,semijoin=on,loosescan=on,firstmatch=on,subquery_materialization_cost_based=on,use_index_extensions=on

As you can see, seeing which option is on or off is rather difficult. You can use the REPLACE function to make this easier:

mysql> select replace(@@optimizer_switch, ',','\n')\G …

This is MySQL's Bad Idea #573 (after #384, which I've blogged about before) I've just had a terrible experience with a bug report from the jOOQ User Group, related to escaping of backslashes in string literals in MySQL. First, I thought to myself, whatever. SQL doesn't escape backslashes. The only escape character within a string … Continue reading MySQL Bad Idea #573 →

This article is part of a series. You might also like: 10 More Common Mistakes Java Developers Make when Writing SQLYet Another 10 Common Mistakes Java Developers Make When Writing SQL Java developers mix object-oriented thinking with imperative thinking, depending on their levels of: Skill (anyone can code imperatively)Dogma (some use the "Pattern-Pattern", i.e. the … Continue reading 10 Common Mistakes Java Developers Make when Writing SQL →

So far, I have been blogging about curious RDBMS caveats mostly related to Oracle and MySQL databases. Some examples: You never stop learning about Oracle features NOT IN vs. NOT EXISTS vs. LEFT JOIN / IS NULL: MySQL SQL incompatibilities: NOT IN and NULL values MySQL Bad Idea #384 But there are also other databases, … Continue reading 10 Things in SQL Server Which Don’t Work as Expected →

SQL tidbits are always valuable and highly searched for by newbies (as opposed to reading the SQL documentation). Sometimes we seasoned SQL developers take for granted little things like when a single- or multiple-character wildcard comparison works. It seems we know what newbies don’t. That you need a wildcard comparison operator not simply and equality comparison operator.

The question posed to me was, “Why doesn’t my wildcard comparison work?” Here’s a simplified example of their question.

SELECT 'Valid' AS "Test"
FROM    dual
WHERE  'Treat' = 'Tre_t'
OR     'Treet' = 'Tre_t';

Naturally, the answer is that the equality operator compares the strings based on their exact match (character sensitively in Oracle and character insensitively in MySQL). It needs to be rewritten by replacing the equals (=) comparison operator with the LIKE …

Join 8000 others and follow Sean Hull on twitter @hullsean. SQL is derided by many and for good reason. It’s key to scalability yet terribly difficult to write good code. Here’s a few quick tips to write tighter queries in MySQL 1. Get rid of those Subqueries! Subqueries are a standard part of SQL, unfortunately […]

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