flink sql

StreamTableEnvironment

该类包含sql解析、验证、优化、执行等各环节需要的元数据管理器CatalogManager,模块管理器(模块包含函数集、类型集、规则集)moduleManager，用户自定义函数管理器FunctionCatalog,线程池、sql解析器Planner。

StreamTableEnvironmentImpl.create(executionEnvironment, settings, new TableConfig)

  def create(
      executionEnvironment: StreamExecutionEnvironment,
      settings: EnvironmentSettings,
      tableConfig: TableConfig)
    : StreamTableEnvironmentImpl = {

    val catalogManager = new CatalogManager(
      settings.getBuiltInCatalogName,
      new GenericInMemoryCatalog(settings.getBuiltInCatalogName, settings.getBuiltInDatabaseName))

    val moduleManager = new ModuleManager
    val functionCatalog = new FunctionCatalog(catalogManager, moduleManager)

    val executorProperties = settings.toExecutorProperties
    val executor = lookupExecutor(executorProperties, executionEnvironment)

    val plannerProperties = settings.toPlannerProperties
    val planner = ComponentFactoryService.find(classOf[PlannerFactory], plannerProperties)
      .create(
        plannerProperties,
        executor,
        tableConfig,
        functionCatalog,
        catalogManager)

    new StreamTableEnvironmentImpl(
      catalogManager,
      moduleManager,
      functionCatalog,
      tableConfig,
      executionEnvironment,
      planner,
      executor,
      settings.isStreamingMode
    )
  }

DataType

定义了逻辑类型，并且对其底层实际物理类型进行暗示。

LogicalType

逻辑类型有点类似标准SQL的数据类型,其子类做了具体的约束。

TableSchema

表结构定义，包含各字段名称和各字段类型

DataStream -> Table

  override def fromDataStream[T](dataStream: DataStream[T], fields: Expression*): Table = {
    val queryOperation = asQueryOperation(dataStream, Some(fields.toList.asJava))
    createTable(queryOperation)
  }

ScalaDataStreamQueryOperation

    private final DataStream<E> dataStream;
    private final int[] fieldIndices;
    private final TableSchema tableSchema;

Table

Table类是sql api的核心组件，定义了转换数据的方法如filter、groupBy、join等。使用TableEnvironment类可以把Table转换成DataStream或者DataSet。

    private TableImpl(
            TableEnvironment tableEnvironment,
            QueryOperation operationTree,
            OperationTreeBuilder operationTreeBuilder,
            LookupCallResolver lookupResolver) {
        this.tableEnvironment = tableEnvironment;
        this.operationTree = operationTree;
        this.operationTreeBuilder = operationTreeBuilder;
        this.lookupResolver = lookupResolver;
    }

注册表信息

    private void createTemporaryView(UnresolvedIdentifier identifier, Table view) {
        if (((TableImpl) view).getTableEnvironment() != this) {
            throw new TableException(
                "Only table API objects that belong to this TableEnvironment can be registered.");
        }

        CatalogBaseTable tableTable = new QueryOperationCatalogView(view.getQueryOperation());

        ObjectIdentifier tableIdentifier = catalogManager.qualifyIdentifier(identifier);
        catalogManager.createTemporaryTable(tableTable, tableIdentifier, false);
    }

Expression

Expression代表字面量、函数调用或者field引用。

ExpressionVisitor

转换Expression的visitor

IndexedExprToFieldInfo

ExpressionVisitor的子类把Expression解析成FieldInfo

        @Override
        public FieldInfo visit(UnresolvedReferenceExpression unresolvedReference) {
            String fieldName = unresolvedReference.getName();
            return new FieldInfo(fieldName, index, fromLegacyInfoToDataType(getTypeAt(unresolvedReference)));
        }

应用举例,把Expression转换成FieldInfo:

    private static List<FieldInfo> extractFieldInfosFromTupleType(TupleTypeInfoBase<?> inputType, Expression[] exprs) {
        boolean isRefByPos = isReferenceByPosition(inputType, exprs);

        if (isRefByPos) {
            return IntStream.range(0, exprs.length)
                .mapToObj(idx -> exprs[idx].accept(new IndexedExprToFieldInfo(inputType, idx)))
                .collect(Collectors.toList());
        } else {
            return extractFieldInfosByNameReference(inputType, exprs);
        }
    }

FieldInfo

        private final String fieldName;
        private final int index;
        private final DataType type;

Row & RowTypeInfo

代表一行数据，可以包含任意数量的列，并且各列可能包含不同的数据类型.Row不是强类型的所以需要配合RowTypeInfo类获取各列具体的类型.

Row:

    /** The array to store actual values. */
    private final Object[] fields;

RowTypeInfo:

    protected final String[] fieldNames;
    protected final TypeInformation<?>[] types;

Table -> DataStream

  override def toAppendStream[T: TypeInformation](table: Table): DataStream[T] = {
    val returnType = createTypeInformation[T]

    val modifyOperation = new OutputConversionModifyOperation(
      table.getQueryOperation,
      TypeConversions.fromLegacyInfoToDataType(returnType),
      OutputConversionModifyOperation.UpdateMode.APPEND)
    toDataStream[T](table, modifyOperation)
  }

Operation

Parser.parse(sql)的返回结果。

ModifyOperation (DML)
QueryOperation (DQL)
CreateOperation & DropOperation (DDL)

FlinkStreamRuleSets

定义了sql解析优化规则集合,包含把calcite节点转换成flink节点的规则，比如FlinkLogicalTableSourceScan,把flink逻辑节点转换成物理执行节点的规则,比如StreamExecTableSourceScanRule，条件过滤下推的规则PushFilterIntoTableSourceScanRule等.

ConverterRule

    /** Converts a relational expression to the target trait(s) of this rule.
    *
    * <p>Returns null if conversion is not possible. */
    public abstract RelNode convert(RelNode rel);
  
    public void onMatch(RelOptRuleCall call) {
    RelNode rel = call.rel(0);
    if (rel.getTraitSet().contains(inTrait)) {
      final RelNode converted = convert(rel);
      if (converted != null) {
        call.transformTo(converted);
      }
    }
  }
  
  class FlinkLogicalTableSourceScanConverter
  extends ConverterRule(
    classOf[LogicalTableScan],
    Convention.NONE,
    FlinkConventions.LOGICAL,
    "FlinkLogicalTableSourceScanConverter") {

  override def matches(call: RelOptRuleCall): Boolean = {
    val scan: TableScan = call.rel(0)
    isTableSourceScan(scan)
  }

  def convert(rel: RelNode): RelNode = {
    val scan = rel.asInstanceOf[TableScan]
    val table = scan.getTable.asInstanceOf[FlinkRelOptTable]
    FlinkLogicalTableSourceScan.create(rel.getCluster, table)
  }
}

FlinkLogicalRel

flink RelNode基类不仅包含了RelNode本身可表达的关系依赖逻辑，而且包含了各关系依赖的Flink体系中的额外信息。比如FlinkLogicalTableSourceScan包含了TableSource信息。

FlinkPhysicalRel

物理关系节点基类,其子类同时也会实现ExecNode接口，用于把物理节点转换成Transformation

ExecNode

  /**
    * Internal method, translates this node into a Flink operator.
    *
    * @param planner The [[Planner]] of the translated Table.
    */
  protected def translateToPlanInternal(planner: E): Transformation[T]
  
  
  def translateToPlan(planner: E): Transformation[T] = {
    if (transformation == null) {
      transformation = translateToPlanInternal(planner)
    }
    transformation
  }

调用时序图