Changyu Bi 4b684e96b7 Allow more intra-L0 compaction when L0 is small (#12214) ... Summary: introduce a new option `intra_l0_compaction_size` to allow more intra-L0 compaction when total L0 size is under a threshold. This option applies only to leveled compaction. It is enabled by default and set to `max_bytes_for_level_base / max_bytes_for_level_multiplier` only for atomic_flush users. When atomic_flush=true, it is more likely that some CF's total L0 size is small when it's eligible for compaction. This option aims to reduce write amplification in this case. Pull Request resolved: https://github.com/facebook/rocksdb/pull/12214 Test Plan: - new unit test - benchmark: ``` TEST_TMPDIR=/dev/shm ./db_bench --benchmarks=fillrandom --write_buffer_size=51200 --max_bytes_for_level_base=5242880 --level0_file_num_compaction_trigger=4 --statistics=1 main: fillrandom : 234.499 micros/op 4264 ops/sec 234.499 seconds 1000000 operations; 0.5 MB/s rocksdb.compact.read.bytes COUNT : 1490756235 rocksdb.compact.write.bytes COUNT : 1469056734 rocksdb.flush.write.bytes COUNT : 71099011 branch: fillrandom : 128.494 micros/op 7782 ops/sec 128.494 seconds 1000000 operations; 0.9 MB/s rocksdb.compact.read.bytes COUNT : 807474156 rocksdb.compact.write.bytes COUNT : 781977610 rocksdb.flush.write.bytes COUNT : 71098785 ``` Reviewed By: ajkr Differential Revision: D52637771 Pulled By: cbi42 fbshipit-source-id: 4f2c7925d0c3a718635c948ea0d4981ed9fabec3		2024-01-22 10:23:57 -08:00
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.gitkeep	Better management of unreleased HISTORY (#11481)	2023-05-30 16:42:49 -07:00
more-intra-l0-compaction.md	Allow more intra-L0 compaction when L0 is small (#12214)	2024-01-22 10:23:57 -08:00