jpountz commented on issue #11761: URL: https://github.com/apache/lucene/issues/11761#issuecomment-1251264246
I got some numbers for write amplification for the case tested in `TestTieredMergePolicy#testSimulateUpdates`: | Allowed percentage of deletes | Write amplification | | ------------- | ------------- | | 50 (max) | 4.34 | | 33 (default) | 4.34 | | 20 (min) | 4.68 | | 10 | 6.13 | | 5 | 8.76 | | 4 | 10.31 | | 3 | 12.97 | | 2 | 18.76 | | 1 | 37.89 | | 0 | 10779.78 | Assuming these numbers are representative, maybe we could allow users to configure 5% as the allowed percentage of deletes that their indexes may have, which translates to ~2x more write amplification compared to the default of 33% according to the above numbers. For reference, the algorithm that `TieredMergePolicy` uses to keep the number of deletes under the threshold consists of running the most balanced merge (with a small bias towards merges that reclaim more deletes) until the number of deletes of the index is under the threshold. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: issues-unsubscr...@lucene.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@lucene.apache.org For additional commands, e-mail: issues-h...@lucene.apache.org
