Track · 2:30 · Liner note
Compaction Sunday
Compaction is background housekeeping in storage engines that merges many small files or segments into fewer larger ones and discards obsolete data, trading some background I/O for faster reads and less disk use.
Sunday is when the housekeeping happens. Storage engines write data in small pieces because that is fast, then compaction merges the pieces into larger ones and drops what is no longer needed. Compaction Sunday is the day the logs, segments or parts tidy themselves up, so reads have fewer files to open and the disk has less to hold.
It costs I/O, so watch when it runs and whether it competes with your peak load. If compaction falls behind ingestion, read latency and disk usage climb together. That is the signal to add capacity or slow the writers.