Apache Ignite Quick Start Guide

SQL functions

Apache Ignite supports custom SQL functions to perform utility tasks. The @QuerySqlFunction Java annotation makes a Java method a SQL function. You can call the function from your ANSI-99 SQL queries. In this section, we are going to write a custom SQL function to convert strings. The steps are as follows:

1. Add a Country class to store id, name, and population:

      class Country {       @QuerySqlField(index = true)       private long id;       @QuerySqlField(index = true)       private String name;       private long population;      public Country(long id, String name, long population) {       super();       this.id = id;       this.name = name;       this.population = population;       }      @Override       public String toString() {       return "Country [id=" + id + ", name=" + name + ",  population=" ...