SchemaKStream¶

SchemaKStream (of K keys) is...FIXME

Creating Instance¶

SchemaKStream takes the following to be created:

• ExecutionStep
• LogicalSchema
• KeyFormat
• KsqlConfig
• FunctionRegistry

SchemaKStream is created when:

• SchemaKSourceFactory is requested for a SchemaKStream
• SchemaKStream is requested to into, filter, flatMap, select and others

Source ExecutionStep¶

ExecutionStep<KStreamHolder<K>> sourceStep

SchemaKStream is given an ExecutionStep (of KStreamHolder<K>) when created.

The ExecutionStep is used for the following (high-level operators):

• filter
• flatMap
• groupBy
• groupByKey
• into
• join
• select
• selectKey

getSourceStep¶

ExecutionStep<?> getSourceStep()

getSourceStep returns the source ExecutionStep.

getSourceStep is used when:

• ExecutionPlanBuilder is requested for the execution plan (of a Query statement)

select¶

SchemaKStream<K> select(
  List<ColumnName> keyColumnNames,
  List<SelectExpression> selectExpressions,
  Stacker contextStacker,
  PlanBuildContext buildContext,
  FormatInfo valueFormat)

select creates a SchemaKStream with a StreamSelect execution step (with the source ExecutionStep).

select is used when:

• AggregateNode is requested to selectRequiredInputColumns, selectRequiredOutputColumns
• ProjectNode is requested to build a SchemaKStream

Resolving LogicalSchema (of ExecutionStep)¶

LogicalSchema resolveSchema(
  ExecutionStep<?> step)

resolveSchema creates a StepSchemaResolver to resolve the LogicalSchema of the given ExecutionStep.