Clean up orphaned objects on s3

Problems

• TRUNCATE and DROP TABLE remove metadata only.
• Long-running queries, merges or other replicas may still reference parts, so ClickHouse delays removal.
• There are bugs in Clickhouse that leave orphaned files, especially after failures.

Solutions

• use our utility for garbage collection - https://github.com/Altinity/s3gc
• or create a separate path in the bucket for every table and every replica and remove the whole path in AWS console
• you can also use clickhouse-disk utility to delete s3 data:

clickhouse-disks --disk s3 --query "remove /cluster/database/table/replica1"