analyzing-schema-change-storage-risk
Estimates storage requirements for CockroachDB online schema change backfills using SHOW RANGES WITH DETAILS, KEYS, INDEXES. Use before CREATE INDEX, ADD COLUMN with INDEX/UNIQUE, ALTER PRIMARY KEY, CREATE MATERIALIZED VIEW, CREATE TABLE AS, REFRESH, or SET LOCALITY on tables with large per-index footprints, to avoid mid-backfill disk exhaustion.
94
92%
Does it follow best practices?
Impact
Pending
No eval scenarios have been run
Passed
No known issues
Quality
Discovery
100%Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.
This is an excellent skill description that precisely defines a narrow, well-scoped capability. It names the specific database system (CockroachDB), the exact SQL commands involved, the concrete problem it solves (disk exhaustion during backfills), and provides explicit 'Use before...' trigger guidance with comprehensive DDL operation coverage. The description is concise yet thorough, using third-person voice throughout.
| Dimension | Reasoning | Score |
|---|---|---|
Specificity | Lists multiple specific concrete actions: estimating storage requirements, using SHOW RANGES WITH DETAILS/KEYS/INDEXES, and names specific schema change operations (CREATE INDEX, ADD COLUMN, ALTER PRIMARY KEY, etc.). | 3 / 3 |
Completeness | Clearly answers both 'what' (estimates storage requirements for CockroachDB online schema change backfills using SHOW RANGES) and 'when' (explicitly states 'Use before CREATE INDEX, ADD COLUMN with INDEX/UNIQUE, ALTER PRIMARY KEY...' with specific trigger conditions like 'large per-index footprints' and 'mid-backfill disk exhaustion'). | 3 / 3 |
Trigger Term Quality | Excellent coverage of natural trigger terms a DBA would use: 'CockroachDB', 'schema change', 'backfill', 'CREATE INDEX', 'ADD COLUMN', 'ALTER PRIMARY KEY', 'disk exhaustion', 'storage requirements', 'SHOW RANGES'. These are precisely the terms users would mention when facing this problem. | 3 / 3 |
Distinctiveness Conflict Risk | Extremely distinct niche: CockroachDB-specific storage estimation for schema change backfills. The combination of CockroachDB + storage estimation + specific DDL operations makes it virtually impossible to conflict with other skills. | 3 / 3 |
Total | 12 / 12 Passed |
Implementation
85%Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.
This is a well-crafted skill with excellent actionability and workflow clarity — the three-step estimation process with executable SQL and a clear decision table is exactly what Claude needs. The main weakness is moderate verbosity in the Background section, which explains CockroachDB internals (AddSSTable, MVCC versions, Pebble compaction) at a level of detail that adds token cost without proportional actionability gains. Overall, it's a strong skill that could be tightened by condensing the background material.
Suggestions
Condense the 'Background' section significantly — the 'What happens if the cluster runs out of disk mid-backfill?' subsection could be reduced to 2-3 sentences noting the safety net behavior and how to resume, rather than explaining AddSSTable internals and the capacity fraction setting.
| Dimension | Reasoning | Score |
|---|---|---|
Conciseness | The Background section explaining how backfills work, what happens on disk exhaustion, and the AddSSTable/InsufficientSpaceError mechanism is useful context but somewhat verbose for Claude. The 'What happens if the cluster runs out of disk mid-backfill?' subsection explains internal mechanics that could be condensed significantly. The core estimation workflow is efficient, but the surrounding explanation adds notable token cost. | 2 / 3 |
Actionability | Provides fully executable SQL queries for each step: checking free space per store, estimating table/index sizes via SHOW RANGES, and checking paused schema change jobs. The comparison table in Step 3 gives concrete thresholds. All queries are copy-paste ready with clear placeholders. | 3 / 3 |
Workflow Clarity | The three-step workflow (check free space → estimate affected size → compare against operation) is clearly sequenced with explicit decision criteria. The operational notes provide error recovery guidance (paused jobs, freeing space). The comparison table serves as a validation checkpoint before proceeding with DDL. | 3 / 3 |
Progressive Disclosure | Content is well-structured with clear sections progressing from when to use, to background, to the estimation workflow, to operational notes. References to related skills and external docs are one level deep and clearly signaled. For a standalone skill with no bundle files, the organization is appropriate and navigable. | 3 / 3 |
Total | 11 / 12 Passed |
Validation
100%Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.
Validation — 11 / 11 Passed
Validation for skill structure
No warnings or errors.
- Repository
- cockroachlabs/cockroachdb-skills
- Commit
84bc1e4
- Reviewed
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