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Posted to dev@flink.apache.org by "Truong Duc Kien (JIRA)" <ji...@apache.org> on 2018/03/25 07:23:00 UTC
[jira] [Created] (FLINK-9070) Improve performance of
RocksDBMapState.clear()
Truong Duc Kien created FLINK-9070:
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Summary: Improve performance of RocksDBMapState.clear()
Key: FLINK-9070
URL: https://issues.apache.org/jira/browse/FLINK-9070
Project: Flink
Issue Type: Improvement
Components: State Backends, Checkpointing
Affects Versions: 1.6.0
Reporter: Truong Duc Kien
Currently, RocksDBMapState.clear() is implemented by iterating over all the keys and drop them one by one. This iteration can be quite slow with:
* Large maps
* High-churn maps with a lot of tombstones
There are a few methods to speed-up deletion for a range of keys, each with their own caveats:
* DeleteRange: still experimental, likely buggy
* DeleteFilesInRange + CompactRange: only good for large ranges
Flink can also keep a list of inserted keys in-memory, then directly delete them without having to iterate over the Rocksdb database again.
Reference:
* [RocksDB article about range deletion|https://github.com/facebook/rocksdb/wiki/Delete-A-Range-Of-Keys]
* [Bug in DeleteRange|https://pingcap.com/blog/2017-09-08-rocksdbbug]
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