Hi Upesh,
The answers to your questions are:
1.
The configs cleanup.policy and retention.ms are topic configs. Hence,
they only affect the changelog of a state store, not the local state
store in a Kafka Streams client.
Locally, window and session stores remove data they do not need anymore.
Window and session stores are segmented stores. That means they consist
of segments that are ordered by the windows they contain. Once the
segment that contains the oldest windows is not needed anymore, i.e.,
the data exceeded the retention time of the state store, the segment is
removed.
Non-windowed state store will not remove data.
Worth noting here: If you change retention.ms directly on the brokers,
it will not affect the behavior of local state stores.
2.
Yes, this behavior is the same for in-memory state stores and persistent
state stores.
3.
Window and session state stores do remove data.
Best,
Bruno
On 18.04.21 18:18, Upesh Desai wrote:
Hello, I have not been able to find a concrete answer on if/how state
stores on a running kafka streams instance remove data when it has
passed the configured retention.ms config. So a couple clarification
questions:
1. If the stores are configured with: cleanup.policy=compact,delete AND
retention.ms=N, will the stores remove data automatically over time
in the running stream instance stores?
2. Is this behavior the same for in-memory stores and persistent
rocksdb stores?
3. If they do not remove data that has passed the retention.ms period,
is there a different way to periodically remove old data from the
stores?
I’m using kafka 2.7.0 components across the board (broker, connect, etc.).
Thanks in advance,
Upesh
<https://www.itrsgroup.com/>
Upesh Desai
Senior Software Developer
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