[FLINK-3097] Add support for custom functions in Table API

• Type: New Feature
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.2.0
• Component/s: Table SQL / API
• Assignee: Timo Walther
• Reporter: Timo Walther
• Created: 01/Dec/15 22:31
• Updated: 15/Aug/16 14:22
• Resolved: 15/Aug/16 14:22

Description

Currently, the Table API has a very limited set of built-in functions. Support for custom functions can solve this problem. Adding of a custom row function could look like:

TableEnvironment tableEnv = new TableEnvironment();

RowFunction<String> rf = new RowFunction<String>() {
    @Override
    public String call(Object[] args) {
        return ((String) args[0]).trim();
    }
};

tableEnv.getConfig().registerRowFunction("TRIM", rf,
    BasicTypeInfo.STRING_TYPE_INFO);

DataSource<Tuple1<String>> input = env.fromElements(
    new Tuple1<>(" 1 "));

Table table = tableEnv.fromDataSet(input);

Table result = table.select("TRIM(f0)");

This feature is also necessary as part of FLINK-2099.

Issue Links

• links to: GitHub Pull Request #2265