# Nodetool compactionhistory **compactionhistory** - Provides the history of compaction operations. For example: `nodetool compactionhistory` Example output: ```yaml id shard_id keyspace_name columnfamily_name compaction_name started_at compacted_at bytes_in bytes_out rows_merged sstables_in sstables_out total_tombstone_purge_attempt total_tombstone_purge_failure_due_to_overlapping_with_memtable total_tombstone_purge_failure_due_to_overlapping_with_uncompacting_sstable 17536e70-5358-11e6-9d5f-000000000000 0 ks test Compact 2024-12-17T16:19:55.914 2024-12-17T16:39:55.914 11000 5583 {1: 78, 2: 6} [{generation: 2a5db691-bc8d-11ef-a5f9-bbbda77f5688, origin: memtable, size: 5468}, {generation: 28c58a60-bc8d-11ef-a5f9-bbbda77f5688, origin: memtable, size: 5532}] [{generation: 2a5fb260-bc8d-11ef-a5f9-bbbda77f5688, origin: compaction, size: 5583}] 3 0 1 4e164760-5354-11e6-9d5f-000000000000 1 ks test Compact 2024-12-17T16:19:55.913 2024-12-17T16:39:55.913 10919 5490 {1: 56, 2: 2} [{generation: 2a5db691-bc8d-11ef-ad72-bbbca77f5688, origin: memtable, size: 5433}, {generation: 28c58a60-bc8d-11ef-ad72-bbbca77f5688, origin: memtable, size: 5486}] [{generation: 2a5f8b50-bc8d-11ef-ad72-bbbca77f5688, origin: compaction, size: 5490}] 1 0 0 17abc7a0-5358-11e6-9710-000000000001 0 system raft Compact 2024-12-17T16:19:52.570 2024-12-17T16:39:52.570 102199 96181 {1: 20, 2: 3} [{generation: 285b08c0-bc8d-11ef-a5f9-bbbda77f5688, origin: memtable, size: 13683}, {generation: 2798ca30-bc8d-11ef-a5f9-bbbda77f5688, origin: compaction, size: 88516}] [{generation: 28614a50-bc8d-11ef-a5f9-bbbda77f5688, origin: compaction, size: 96181}] 1 0 0 18537950-5358-11e6-be35-000000000002 0 system_schema columns Compact 2024-12-17T16:19:52.563 2024-12-17T16:39:52.563 25478 19882 {1: 506} [{generation: 28545200-bc8d-11ef-a5f9-bbbda77f5688, origin: memtable, size: 5744}, {generation: 279a02b0-bc8d-11ef-a5f9-bbbda77f5688, origin: compaction, size: 19734}] [{generation: 286011d0-bc8d-11ef-a5f9-bbbda77f5688, origin: compaction, size: 19882}] 15 0 0 19452c50-5358-11e6-8491-000000000003 0 system topology Compact 2024-12-17T16:19:52.555 2024-12-17T16:39:52.555 22197 14236 {2: 4} [{generation: 00000000-0000-1000-0000-000000000002, origin: memtable, size: 9296}, {generation: 285ba501-bc8d-11ef-a5f9-bbbda77f5688, origin: memtable, size: 12901}] [{generation: 285e3d10-bc8d-11ef-a5f9-bbbda77f5688, origin: compaction, size: 14236}] 0 0 0 ``` Explanation: | Parameter | Description | |----------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------| | id | id of the compaction | | shard_id | id of the shard the compaction was executed on | | keyspace_name | keyspace name that the compaction performed on | | columnfamily_name | columnfamily name that the compaction performed on | | compaction_type | type of compaction, e.g. major, regular, reshard, cleanup, etc. | | started_at | timestamp when the compaction started | | compacted_at | timestamp when the compaction completed | | bytes_in | SSTable size before the compaction | | bytes_out | SSTable size after the compaction | | rows_merged | histogram of merged data (takes into account clustering rows, static rows, range tombstones, etc.) | | sstables_in | list of sstables that were the input of the compaction | | sstables_out | list of sstables that were the output of the compaction (usually one; with ICS/LCS it can be more) | | total_tombstone_purge_attempt | total amount of tombstones that were candidates for garbage-collection | | total_tombstone_purge_failure_due_to_overlapping_with_memtable | purgeable tombstone which couldn’t be collected because memtable contains possibly shadowed data | | total_tombstone_purge_failure_due_to_overlapping_with_uncompacting_sstable | purgeable tombstone which couldn’t be collected because other sstables contains possibly shadowed data | ## Output formats Use `--format` (`-F`) to select the output format, one of `text` (the default), `json`, `yaml` or `log`. The `log` format reproduces the lines the compaction logger would have emitted at `debug` level when each compaction started and finished. Since the compaction log is not enabled by default, this allows the compaction activity to be put back into the node’s log, by sorting the two together by timestamp: ```console nodetool compactionhistory -F log > history.log sort -k2 scylla.log history.log > merged.log ``` Example output: ```console DEBUG 2024-12-17 16:19:55,914 [shard 0:comp] compaction - [Compact ks.test 17536e70-5358-11e6-9d5f-000000000000] Compacting [{generation: 2a5db691-bc8d-11ef-a5f9-bbbda77f5688, origin: memtable, size: 5468},{generation: 28c58a60-bc8d-11ef-a5f9-bbbda77f5688, origin: memtable, size: 5532}] DEBUG 2024-12-17 16:39:55,914 [shard 0:comp] compaction - [Compact ks.test 17536e70-5358-11e6-9d5f-000000000000] Compacted 2 sstables to [{generation: 2a5fb260-bc8d-11ef-a5f9-bbbda77f5688, origin: compaction, size: 5583}]. 11kB to 5583 bytes (~50% of original) in 1200000ms = 9 bytes/s. ``` The compaction history doesn’t record everything the original log line carries, so the SSTables are identified by generation rather than by file name, and the partition counts are left out. [Nodetool Reference](https://docs.scylladb.com/manual/branch-2026.4/operating-scylla/nodetool.md)