d1-cost-optimizer
Skill2 starsChanged 5 months agoApache-2.0View on GitHub
Cloudflare D1 database cost optimization expert. Analyzes SQL query Row Reads consumption, identifies cost explosion risks, and provides index optimization, query rewriting, and denormalization strategies. Trigger when user mentions D1, Row Reads, query optimization, or database cost.
In this repository8 other files it gives its agents.
- cloudflare-auditSkill
- cost-audit-masterSkill
- cost-monitorSkill
- index-optimizerSkill
- query-rewriterSkill
- redis-auditSkill
- spend-cap-managerSkill
- supabase-auditSkill
The file
We split this skill into the rules it gives an agent
1 rule. About 0 are common, 0 are distinctive, and 1 is very specific to this project.
≈0
Common · estimate
Many files like this have a rule of this kind.
≈0
Distinctive · estimate
This author's own choices. Worth a look.
1
Very specific
Tied to their project's names, files or tools. Probably skip.
- Common
- Distinctive
- Very specific
- Very specific: line 44
Use EXPLAIN QUERY PLAN to identify:
≈ “Common” is an estimate: at least 1 in 5 of the 350,495 skill files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.
Files
Cloudflare D1 Cost Optimization Expert
Core Principle
D1 billing is based on Row Reads (rows scanned), not rows returned. Cost explosion typically comes from uncontrolled Row Reads.
Common Anti-Patterns
| Anti-Pattern | Problem | Reference |
| Missing indexes | Full table scans | references/unindexed-join.md |
| Deep OFFSET | Scans discarded rows | references/deep-pagination.md |
| SELECT * | Fetches unnecessary data | references/select-star-all.md |
| Full table scan | No WHERE clause | references/full-table-scan.md |
| Query in loop | N+1 problem | references/subquery-in-loop.md |
| LIKE '%xxx%' | Leading wildcard | references/like-wildcard.md |
| ORDER BY without index | Temporary sort | references/order-by-no-index.md |
| Function on column | Prevents index use | references/function-on-indexed-column.md |
| OR across columns | Cannot use index | references/or-instead-of-union.md |
| NOT IN subquery | NULL issues | references/not-in-subquery.md |
| Type mismatch | Implicit conversion | references/implicit-type-conversion.md |
| Multiple aggregations | Multiple scans | references/multiple-aggregations.md |
| COUNT(*) without index | Full scan | references/select-count-star.md |
| UNION vs UNION ALL | Unnecessary dedup | references/union-all-vs-union.md |
| COUNT queries | Expensive aggregation | references/denormalization-trigger.md |
| Repeated queries | No caching | references/worker-cache.md |
Audit Workflow
Step 1: Analyze Current Query Row Reads
Use EXPLAIN QUERY PLAN to identify:
SCAN TABLE= Full table scan = Cost bombSEARCH TABLE USING INDEX= Using index = GoodUSE TEMP B-TREE FOR= Extra sorting = Needs optimization
Step 2: Check Missing Indexes
-- List all indexes
SELECT name, sql FROM sqlite_master WHERE type='index' AND sql IS NOT NULL;
-- Check foreign keys
SELECT * FROM pragma_foreign_key_list('<table_name>');Step 3: Match Anti-Pattern
Identify which anti-pattern the query matches and apply the corresponding solution from the reference file.
Step 4: Verify Optimization
# Check query plan after optimization
wrangler d1 execute <database> --command "EXPLAIN QUERY PLAN <optimized_query>"Benchmark Reference
| Scenario | Before | After | Improvement |
| Unindexed JOIN | 1B Row Reads | 20 | 99.9998% |
| Deep OFFSET | 10,020 reads | 20 | 99.8% |
| Denormalized COUNT | 1M reads | 20 | 99.998% |
| Worker Cache hit | 20 reads | 0 | 100% |
| SELECT * vs specific | 200KB | 20KB | 90% |
| Query in loop | 10,000 | 1,000 | 90% |
| LIKE wildcard | 100,000 | 500 | 99.5% |
| OR vs UNION | 100,000 | 2 | 99.998% |
Output Format
## D1 Cost Audit Report
### 1. Current Status
- Database: <name>
- Tables: X
- Total rows: X
### 2. Anti-Patterns Detected
| Query | Anti-Pattern | Reference | Fix |
|-------|--------------|-----------|-----|
| ... | ... | ... | ... |
### 3. Index Check
- Missing indexes: X
- Redundant indexes: X
### 4. Recommendations (by priority)
1. [P0] Fix: <anti-pattern> → Expected improvement: XX%
Reference: references/<file>.md
### 5. Implementation
Apply fixes from referenced files.Does it work?
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