kafka-streams-internals-GlobalKTableImpl.adoc

GlobalKTableImpl

GlobalKTableImpl is a GlobalKTable (of K primary keys and V value changes) that uses a KTableValueGetterSupplier for the queryableStoreName when queryable.

GlobalKTableImpl is created exclusively when InternalStreamsBuilder is requested to add a global table to a topology (exclusively when StreamsBuilder is requested to create a GlobalKTable).

import org.apache.kafka.streams.StreamsBuilder
val builder = new StreamsBuilder

val globalTable = builder.globalTable("topic")

import org.apache.kafka.streams.kstream.internals.GlobalKTableImpl
val impl = globalTable.asInstanceOf[GlobalKTableImpl[_, _]]

scala> println(impl.queryableStoreName)
null

Creating GlobalKTableImpl Instance

GlobalKTableImpl takes the following when created:

• KTableValueGetterSupplier (of K primary keys and V value changes)

• queryable flag

queryableStoreName Method

String queryableStoreName()

Note	queryableStoreName is part of GlobalKTable Contract to…​FIXME.

Only when queryable is enabled, queryableStoreName requests the KTableValueGetterSupplier for storeNames and takes the very first one.

Otherwise, queryableStoreName returns null.