Java Developer

MySQL issue with N and Ñ treated as equal value

I encountered and issue today where I have a table of person records. Some last name have values of IBAÑEZ and some have IBANEZ.

Fast Fuzzy String Matching with Grails/Hibernate and MySQL

The popular fuzzy string matching methods are Levenshtein distance, Soundex, Metaphone and Double Metaphone. I created a post on Levenshtein distance here. But the performance is very disappointing. Scanning 40,000 records took around 25 seconds.
An alternative is Soundex. It has some deficiencies in terms of accuracy, specially if the language is not English. However, since this is the most widely known phonetic algorithm, it has native support in MySQL. It is also extremely fast. When I switched algorithms, the query ran from 25 seconds from Levenshtein, down to a fraction of a second for Soundex.

Grails fuzzy string matching with MySQL and Levenshtein distance

This is a hackish approach for fuzzy string matching in Grails, as an alternative to searchable plugin, assuming MySQL database is used.
As an introduction, the levenshtein distance is used on how similar two strings are. It computes the minimum number of character substitution that has to be done, in order to convert one string from the other. For example, if the levenshtein distance is 0, it means the two strings are exactly the same. If levenshtein distance is 1, it means there is only 1 character differing the two strings. We can use this function for fuzzy matching using a very small treshold for the distance.

Adding SQL logging to your Grails application

While ORM is great in simplifying our work with the database, it is still very useful to know SQL statements our application is throwing at the database. Specially when we are still developing the application.

Understanding Grails dbCreate or hbm2ddl

One of the convenient features of Hibernate that is inherited by Grails, is that once you have defined your data model, it can create the tables for you automatically on start up of the application. The nice thing about this is since Hibernate/GORM is database agnostic, it means you don't need to know how to define the tables in different relational databases. Be it Oracle, DB2, or MySQL. If you change your connection property, and load the appropriate JDBC driver, it will know how to talk to the database and create the correct tables.

Specifying MyISAM or InnoDB MySQL storage engine in Grails

MySQL is a popular choice of database for many developers. It's open source, easy to install, stable, and very fast. However, MySQL comes with several storage engine and you need to decide which one to choose. The two most popular are:
  • MyISAM - this is the default storage engine for MySQL prior to version 5.5. I believe this is the fastest storage engine of all, but the drawside is it does not support transactions.
  • InnoDB - this is not as fast as MyISAM, but it support transactions. This is the most popular among Java/Grails developers.

Configuring MySQL JDBC connection for Grails

During development, I recommend using a standalone database server like MySQL, instead of using the default HSQLDB or H2 database. Because you can open a client and inspect the table structure created, and also perform queries outside the Grails application.
To configure MySQL in your datasource, first download the driver from:

Restore mysql backup with progress bar

I wanted to restore a large production database before in my home computer, to replicate a particular bug. Since the database dump is so large, it took a lot of time. Around 30 minutes. The issue with such operation is that you don't know if the MySQL process hanged-up, or if it is still normally progressing. A good solution is to have a progress bar.

Using Tomcat JNDI datasource when deploying Grails production war

When developing a grails application, it is acceptable to hard code the database connection in DataSource.groovy. But when you want to create a war and deploy it on an application server, it is better to use JNDI. This is more flexible because you can change the connection property in the application server, instead of creating a new war.

Configuring MySQL for faster development performance

The default configuration of MySQL is not very fast. They made it generic so that it can run on servers with small memory (For example, a VPS with 256Mb RAM). But desktop nowadays have so much memory and disk space that we can trade off for faster performance.
Performance is important because it affects your productivity. I have experimented with many configurations, but below is the simplest that I came up with that gave me good results.