When a MySQL table accumulates 52GB of fragmentation, the disk alert forces a quick decision. The tempting shortcut is TRUNCATE, but on a live business table that means instant data loss. This incident report walks through the safer path: first confirm the fragmentation with information_schema, then use ALTER TABLE ... ENGINE=InnoDB or pt-online-schema-change to rebuild the table without blocking writes. The author also emphasizes checking table size, row counts, and replication lag before any operation. For teams running MySQL in production, this is a classic scenario that deserves a documented runbook. The key takeaway is not the specific commands but the decision framework: never TRUNCATE a table you cannot afford to lose, always have a rollback plan, and test the rebuild on a staging copy first. Disk space management is an evergreen operational concern, and this case study provides a practical template for handling it safely.
A production MySQL table accumulated 52GB of fragmentation, triggering a disk 80% alert. The author nearly used TRUNCATE on a live business table before realizing the risk. The post walks through safe alternatives and operational guardrails for reclaiming space without data loss.