[
https://issues.apache.org/jira/browse/FLINK-4469?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15636651#comment-15636651
]
ASF GitHub Bot commented on FLINK-4469:
---------------------------------------
Github user sunjincheng121 commented on a diff in the pull request:
https://github.com/apache/flink/pull/2653#discussion_r86557322
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/api/table/TableEnvironment.scala
---
@@ -152,21 +153,40 @@ abstract class TableEnvironment(val config:
TableConfig) {
protected def getBuiltInRuleSet: RuleSet
/**
- * Registers a [[UserDefinedFunction]] under a unique name. Replaces
already existing
+ * Registers a [[ScalarFunction]] under a unique name. Replaces already
existing
* user-defined functions under this name.
*/
- def registerFunction(name: String, function: UserDefinedFunction): Unit
= {
- function match {
- case sf: ScalarFunction =>
- // register in Table API
- functionCatalog.registerFunction(name, function.getClass)
+ def registerFunction(name: String, function: ScalarFunction): Unit = {
+ // register in Table API
+ functionCatalog.registerFunction(name, function.getClass)
- // register in SQL API
- functionCatalog.registerSqlFunction(sf.getSqlFunction(name,
typeFactory))
+ // register in SQL API
+ functionCatalog.registerSqlFunction(function.getSqlFunction(name,
typeFactory))
+ }
+
+ /**
+ * Registers a [[TableFunction]] under a unique name. Replaces already
existing
+ * user-defined functions under this name.
+ */
+ private[flink] def registerTableFunctionInternal[T: TypeInformation](
+ name: String, tf: TableFunction[T]): Unit = {
- case _ =>
- throw new TableException("Unsupported user-defined function type.")
+ val typeInfo: TypeInformation[_] = if (tf.getResultType != null) {
+ tf.getResultType
+ } else {
+ implicitly[TypeInformation[T]]
}
+
+ val (fieldNames, fieldIndexes) =
UserDefinedFunctionUtils.getFieldInfo(typeInfo)
--- End diff --
For the sake of simplicity, is it possible to encapsulate a
”createSqlFunctions“ method in tablefunciton?
> Add support for user defined table function in Table API & SQL
> --------------------------------------------------------------
>
> Key: FLINK-4469
> URL: https://issues.apache.org/jira/browse/FLINK-4469
> Project: Flink
> Issue Type: New Feature
> Components: Table API & SQL
> Reporter: Jark Wu
> Assignee: Jark Wu
>
> Normal user-defined functions, such as concat(), take in a single input row
> and output a single output row. In contrast, table-generating functions
> transform a single input row to multiple output rows. It is very useful in
> some cases, such as look up in HBase by rowkey and return one or more rows.
> Adding a user defined table function should:
> 1. inherit from UDTF class with specific generic type T
> 2. define one or more evel function.
> NOTE:
> 1. the eval method must be public and non-static.
> 2. the generic type T is the row type returned by table function. Because of
> Java type erasure, we can’t extract T from the Iterable.
> 3. use {{collect(T)}} to emit table row
> 4. eval method can be overload. Blink will choose the best match eval method
> to call according to parameter types and number.
> {code}
> public class Word {
> public String word;
> public Integer length;
> }
> public class SplitStringUDTF extends UDTF<Word> {
> public Iterable<Word> eval(String str) {
> if (str != null) {
> for (String s : str.split(",")) {
> collect(new Word(s, s.length()));
> }
> }
> }
> }
> // in SQL
> tableEnv.registerFunction("split", new SplitStringUDTF())
> tableEnv.sql("SELECT a, b, t.* FROM MyTable, LATERAL TABLE(split(c)) AS
> t(w,l)")
> // in Java Table API
> tableEnv.registerFunction("split", new SplitStringUDTF())
> // rename split table columns to “w” and “l”
> table.crossApply("split(c) as (w, l)")
> .select("a, b, w, l")
> // without renaming, we will use the origin field names in the POJO/case/...
> table.crossApply("split(c)")
> .select("a, b, word, length")
> // in Scala Table API
> val split = new SplitStringUDTF()
> table.crossApply(split('c) as ('w, 'l))
> .select('a, 'b, 'w, 'l)
> // outerApply for outer join to a UDTF
> table.outerApply(split('c))
> .select('a, 'b, 'word, 'length)
> {code}
> See [1] for more information about UDTF design.
> [1]
> https://docs.google.com/document/d/15iVc1781dxYWm3loVQlESYvMAxEzbbuVFPZWBYuY1Ek/edit#
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