GitHub user wuchong opened a pull request:
https://github.com/apache/flink/pull/2653
[FLINK-4469] [table] Add support for user defined table function in Table
API & SQL
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This PR introduces user-defined table functions for the Table and SQL API.
I will add documentation after this proposal is accepted. This is the
general syntax so far:
In Java:
```java
public class Split extends TableFunction<String> {
public int eval(String str) {
for (String s : str.split(" ")) {
collect(s);
}
}
}
tableEnv.registerFunction("split", new Split());
// cross apply
Table result = table.crossApply("split(c)", "s").select("c, s")
Table result = tableEnv.sql("SELECT MyTable.c, t.s FROM MyTable CROSS APPLY
split(c) as t(s)")
// outer apply
Table result = table.outerApply("split(c)", "s").select("c, s")
Table result = tableEnv.sql("SELECT MyTable.c, t.s FROM MyTable OUTER APPLY
split(c) as t(s)")
```
In Scala
```scala
object Split extends TableFunction<String> {
def eval(str: String): Unit = {
str.split(" ").foreach(collect)
}
}
// cross apply
val result = table.crossApply(Split('c) as ('s)).select('c, 's)
tableEnv.registerFunction("split", Split);
val result = tableEnv.sql("SELECT MyTable.c, t.s FROM MyTable CROSS APPLY
split(c) as t(s)")
// outer apply
val result = table.outerApply(Split('c) as ('s)).select('c, 's)
tableEnv.registerFunction("split", Split);
val result = tableEnv.sql("SELECT MyTable.c, t.s FROM MyTable OUTER APPLY
split(c) as t(s)")
```
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/wuchong/flink udtf-FLINK-4469
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/flink/pull/2653.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #2653
----
commit 60812e51156ec9fa6088154d2f6dea8c1ff9ac17
Author: Jark Wu <[email protected]>
Date: 2016-10-18T03:15:07Z
[FLINK-4469] [table] Add support for user defined table function in Table
API & SQL
----
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