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Ted Yu commented on KAFKA-9450: ------------------------------- w.r.t. separate column family, since the data in this family tends to be small compared to the data family, wouldn't we end up with small files similar to rocksdb memtable flush ? > Decouple inner state flushing from committing with EOS > ------------------------------------------------------ > > Key: KAFKA-9450 > URL: https://issues.apache.org/jira/browse/KAFKA-9450 > Project: Kafka > Issue Type: Improvement > Components: streams > Reporter: Sophie Blee-Goldman > Priority: Major > > When EOS is turned on, the commit interval is set quite low (100ms) and all > the store layers are flushed during a commit. This is necessary for > forwarding records in the cache to the changelog, but unfortunately also > forces rocksdb to flush the current memtable before it's full. The result is > a large number of small writes to disk, losing the benefits of batching, and > a large number of very small L0 files that are likely to slow compaction. > Since we have to delete the stores to recreate from scratch anyways during an > unclean shutdown with EOS, we may as well skip flushing the innermost > StateStore during a commit and only do so during a graceful shutdown, before > a rebalance, etc. This is currently blocked on a refactoring of the state > store layers to allow decoupling the flush of the caching layer from the > actual state store. -- This message was sent by Atlassian Jira (v8.3.4#803005)