Mutation tracking and analysis

Answers "why is this mutation stuck or slow" from system.mutations, system.merges, system.parts, system.replication_queue and system.part_log. Mutations rewrite whole parts in the background; they are not transactional row updates. Run altinity-expert-clickhouse-connection first if the connection mode, cluster and time window are not yet established.

Query packs

• checks.sql — 11 checks: current mutation status, per-table mutation summary, stuck mutation detection by age, recently completed mutations, mutation duration per table, failed mutations in the part log, mutations executing right now, parts still awaiting mutation, mutation versus merge competition for the background pool, mutation creation rate and a breakdown by mutation command type. 3 of them need system.part_log.
• reference.md — background (settings, sizing, anti-patterns); read only when you need to explain a recommendation.

How to run the query packs

1. Read each pack file from this skill's directory (the skill loader prints the directory path).
2. Run statements one at a time, never a whole file. Statements end with ; and start with a -- @check <id> <title> header; keep the id with its result.
3. Honor -- @requires: skip the statement when the named table is missing, when keeper is required and the server has no Keeper/ZooKeeper, or when the version condition is not met. List skipped ids with the reason.
4. Keep {cluster} as written when a cluster macro exists; otherwise apply the connection skill's rewrite rule. Any other {placeholder} is a template variable: substitute a real value first or skip the statement.
5. On an error, record the check id and the first line of the error, then continue. Only for UNKNOWN_IDENTIFIER, run DESCRIBE TABLE system.<table> and drop the missing column.
6. A severity column is the verdict for that row. Copy it; do not re-grade.