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https://issues.apache.org/jira/browse/FLINK-7062?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16651748#comment-16651748
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ASF GitHub Bot commented on FLINK-7062:
---------------------------------------
dawidwys commented on a change in pull request #6815: [FLINK-7062][cep][table]
Added basic support for MATCH_RECOGNIZE
URL: https://github.com/apache/flink/pull/6815#discussion_r225551310
##########
File path:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/codegen/MatchCodeGenerator.scala
##########
@@ -0,0 +1,320 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.table.codegen
+
+import java.util
+
+import org.apache.calcite.rex._
+import org.apache.calcite.sql.fun.SqlStdOperatorTable._
+import org.apache.flink.api.common.functions._
+import org.apache.flink.api.common.typeinfo.TypeInformation
+import org.apache.flink.api.java.typeutils.ListTypeInfo
+import org.apache.flink.cep.pattern.conditions.IterativeCondition
+import org.apache.flink.cep.{PatternFlatSelectFunction, PatternSelectFunction}
+import org.apache.flink.table.api.{TableConfig, TableException}
+import org.apache.flink.table.codegen.CodeGenUtils.{boxedTypeTermForTypeInfo,
newName, primitiveDefaultValue}
+import org.apache.flink.table.codegen.Indenter.toISC
+import org.apache.flink.table.plan.schema.RowSchema
+import org.apache.flink.util.Collector
+import org.apache.flink.util.MathUtils.checkedDownCast
+import java.lang.{Long => JLong}
+
+import scala.collection.JavaConverters._
+
+/**
+ * A code generator for generating CEP related functions.
+ *
+ * @param config configuration that determines runtime behavior
+ * @param nullableInput input(s) can be null.
+ * @param input type information about the first input of the Function
+ * @param currentPattern if generating condition the name of pattern, which
the condition will
+ * be applied to
+ */
+class MatchCodeGenerator(
+ config: TableConfig,
+ nullableInput: Boolean,
+ input: TypeInformation[_ <: Any],
+ currentPattern: Option[String] = None)
+ extends CodeGenerator(config, nullableInput, input){
+
+ def generateMatchFunction[F <: Function, T <: Any](
+ name: String,
+ clazz: Class[F],
+ bodyCode: String,
+ returnType: TypeInformation[T])
+ : GeneratedFunction[F, T] = {
+ // This is a separate method from FunctionCodeGenerator#generateFunction
because as of now
+ // functions in CEP library do not support rich interfaces
+ val funcName = newName(name)
+ val collectorTypeTerm = classOf[Collector[Any]].getCanonicalName
+ val (functionClass, signature, inputStatements, isInterface) =
+ if (clazz == classOf[IterativeCondition[_]]) {
+ val baseClass = classOf[IterativeCondition[_]]
+ val inputTypeTerm = boxedTypeTermForTypeInfo(input)
+ val contextType =
classOf[IterativeCondition.Context[_]].getCanonicalName
+
+ (baseClass,
+ s"boolean filter( Object _in1, $contextType $contextTerm)",
+ List(s"$inputTypeTerm $input1Term = ($inputTypeTerm) _in1;"),
+ false)
+ } else if (clazz == classOf[PatternSelectFunction[_, _]]) {
+ val baseClass = classOf[PatternSelectFunction[_, _]]
+ val inputTypeTerm =
+ s"java.util.Map<String,
java.util.List<${boxedTypeTermForTypeInfo(input)}>>"
+
+ (baseClass,
+ s"Object select($inputTypeTerm $input1Term)",
+ List(),
+ true)
+ } else if (clazz == classOf[PatternFlatSelectFunction[_, _]]) {
+ val baseClass = classOf[PatternFlatSelectFunction[_, _]]
+ val inputTypeTerm =
+ s"java.util.Map<String,
java.util.List<${boxedTypeTermForTypeInfo(input)}>>"
+
+ (baseClass,
+ s"void flatSelect($inputTypeTerm $input1Term, $collectorTypeTerm
$collectorTerm)",
+ List(),
+ true)
+ } else {
+ throw new CodeGenException("Unsupported Function.")
+ }
+
+ val extendsKeyword = if (isInterface) "implements" else "extends"
+ val funcCode = j"""
+ |public class $funcName $extendsKeyword
${functionClass.getCanonicalName} {
+ |
+ | ${reuseMemberCode()}
+ |
+ | public $funcName() throws Exception {
+ | ${reuseInitCode()}
+ | }
+ |
+ | @Override
+ | public $signature throws Exception {
+ | ${inputStatements.mkString("\n")}
+ | ${reusePerRecordCode()}
+ | ${reuseInputUnboxingCode()}
+ | $bodyCode
+ | }
+ |}
+ """.stripMargin
+
+ GeneratedFunction(funcName, returnType, funcCode)
+ }
+
+ def generatePartitionKeyAccess(
+ partitionKey: RexInputRef
+ ) : GeneratedExpression = {
+ // extracts partition keys from any element of the match
+ val eventNameTerm = newName("event")
+ val eventTypeTerm = boxedTypeTermForTypeInfo(input)
+
+ val keyAccess = generateFieldAccess(input, eventNameTerm,
partitionKey.getIndex)
+
+ val keyCode = s"""
+ |$eventTypeTerm $eventNameTerm = null;
+ |for (java.util.Map.Entry entry : $input1Term.entrySet()) {
+ | java.util.List<$eventTypeTerm> value =
(java.util.List<$eventTypeTerm>) entry.getValue();
+ | if (value != null && value.size() > 0) {
+ | $eventNameTerm = ($eventTypeTerm) value.get(0);
+ | break;
+ | }
+ |}
+ |
+ |${keyAccess.code}
+ """.stripMargin
+
+ keyAccess.copy(code = keyCode)
+ }
+
+ def generateOneRowPerMatchExpression(
+ partitionKeys: util.List[RexNode],
+ measures: util.Map[String, RexNode],
+ returnType: RowSchema
+ ): GeneratedExpression = {
+ // For "ONE ROW PER MATCH", the output columns include:
+ // 1) the partition columns;
+ // 2) the columns defined in the measures clause.
+ val resultExprs =
+ partitionKeys.asScala.map { case inputRef: RexInputRef =>
+ generatePartitionKeyAccess(inputRef)
+ } ++ returnType.fieldNames.filter(measures.containsKey(_)).map {
fieldName =>
+ generateExpression(measures.get(fieldName))
+ }
+
+ generateResultExpression(
+ resultExprs,
+ returnType.typeInfo,
+ returnType.fieldNames)
+ }
+
+ override def visitCall(call: RexCall): GeneratedExpression = {
+ call.getOperator match {
+ case PREV | NEXT =>
+ val countLiteral = call.operands.get(1).asInstanceOf[RexLiteral]
+ val count = countLiteral.getValueAs(classOf[JLong])
+ if (count != 0) {
+ throw new TableException("Flink does not support physical offsets
within partition.")
Review comment:
No we do not support physical offsets at all. Physical offset index elements
independently from which rows were matched, e.g. you can index to before the
start of a match. We do not have access to such elements.
The `if` clause here is only because calcite translates every PRV into
`PREV` call.
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> Support the basic functionality of MATCH_RECOGNIZE
> --------------------------------------------------
>
> Key: FLINK-7062
> URL: https://issues.apache.org/jira/browse/FLINK-7062
> Project: Flink
> Issue Type: Sub-task
> Components: CEP, Table API & SQL
> Reporter: Dian Fu
> Assignee: Dian Fu
> Priority: Major
> Labels: pull-request-available
>
> In this JIRA, we will support the basic functionality of {{MATCH_RECOGNIZE}}
> in Flink SQL API which includes the support of syntax {{MEASURES}},
> {{PATTERN}} and {{DEFINE}}. This would allow users write basic cep use cases
> with SQL like the following example:
> {code}
> SELECT T.aid, T.bid, T.cid
> FROM MyTable
> MATCH_RECOGNIZE (
> MEASURES
> A.id AS aid,
> B.id AS bid,
> C.id AS cid
> PATTERN (A B C)
> DEFINE
> A AS A.name = 'a',
> B AS B.name = 'b',
> C AS C.name = 'c'
> ) AS T
> {code}
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