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Posted to issues@flink.apache.org by "Usamah Jassat (Jira)" <ji...@apache.org> on 2022/07/13 14:04:00 UTC

[jira] [Created] (FLINK-28539) Enable CompactionDynamicLevelBytes in FLASH_SSD_OPTIMIZED

Usamah Jassat created FLINK-28539:
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             Summary: Enable CompactionDynamicLevelBytes in FLASH_SSD_OPTIMIZED
                 Key: FLINK-28539
                 URL: https://issues.apache.org/jira/browse/FLINK-28539
             Project: Flink
          Issue Type: Improvement
          Components: Runtime / State Backends
            Reporter: Usamah Jassat


Investigating the RocksDB predefined options I see that `setLevelCompactionDynamicLevelBytes` is set for SPINNING_DISK options but not FLASH_SSD_OPTIMIZED.

 

From my research it looks like this change would improve the Space Amplification of RocksDB [1] (which can also lead to a trade-off from read/write amplification [2]). It makes sense to me that this feature should be enabled for SSD's as they tend to have less space compared to their HDD counterparts.

There is also an argument to be made to also disable it for SPINNING_DISK options as it could give increased read/write performance [2]

[1] [http://rocksdb.org/blog/2015/07/23/dynamic-level.html]

[2] [https://github.com/EighteenZi/rocksdb_wiki/blob/master/RocksDB-Tuning-Guide.md#amplification-factors]



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