kafka-streams-internals-StoreChangeLogger.adoc

StoreChangeLogger

StoreChangeLogger is created when the following state stores are requested to initialize:

• ChangeLoggingKeyValueBytesStore

• ChangeLoggingSessionBytesStore

• ChangeLoggingWindowBytesStore

Creating StoreChangeLogger Instance

StoreChangeLogger takes the following to be created:

• Name of a state store

• ProcessorContext

• Partition ID

• StateSerdes<K, V>

StoreChangeLogger initializes the internal properties.

logChange Method

void logChange(K key, V value) // (1)
void logChange(K key, V value, long timestamp)

1. Uses the ProcessorContext for the timestamp

logChange simply requests the RecordCollector to send the key and the value to the topic and the partition (using the keySerializer and the valueSerializer).

Note	logChange is used when: ChangeLoggingKeyValueBytesStore is requested to log ChangeLoggingSessionBytesStore is requested to remove and put ChangeLoggingWindowBytesStore is requested to log ChangeLoggingTimestampedKeyValueBytesStore and ChangeLoggingTimestampedWindowBytesStore are requested to log

Internal Properties

Name	Description
collector	RecordCollector Used exclusively when StoreChangeLogger is requested to logChange.
topic	The name of the changelog topic (given the application ID and the store name) Used when…​FIXME