feat: Add Readme

[asungur]

Documentation

[claude]

Pull Request Review - README Documentation

Thank you for adding comprehensive documentation for Squid! This README provides excellent coverage of the library's features with clear, practical examples. I've reviewed the documentation against the actual codebase implementation and have the following feedback:

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✅ Strengths

1. Excellent Structure and Organization

• Clear progression from basic usage to advanced features
• Well-organized sections with practical code examples
• The design section helps users understand the underlying architecture
• Good use of tables for key encoding patterns

2. Accurate API Documentation

• All code examples match the actual implementation
• Proper use of types, method signatures, and package imports
• Examples demonstrate real-world usage patterns

3. Helpful Notes

• The CSV export note explaining flattened fields is very useful
• Links to GitHub issues for contributions
• Clear explanation of ULID usage and chronological sorting

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📝 Documentation Issues & Suggestions

1. Incomplete Aggregation Example

Location: README.md:86-102

The aggregation example requests 8 aggregation types but only shows 3 results. Either show all requested aggregations or request only the ones you display.

2. Missing Context Cancellation Example

The Query and Aggregate functions accept context.Context for cancellation support, but no examples demonstrate this important feature.

3. Missing Error Handling in Examples

Several examples ignore error returns, which could mislead beginners (lines 118, 128, 133, 137).

4. Retention Policy Defaults Not Documented

The README doesn't mention that CleanupInterval defaults to MaxAge/10 with a minimum of 1 minute if not specified (retention.go:59-63).

5. Missing Important Limitations

Consider adding a "Limitations" or "Performance Considerations" section mentioning:

• Percentile calculations are limited to 1,000,000 values to prevent memory exhaustion (aggregation.go:37)
• Tag queries currently use only the first tag for index selection (query.go:87-90)
• Multiple type filters don't use union index optimization yet (query.go:79)
• Query.Limit has no validation - large values could cause issues (query.go:27)

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🔒 Security Considerations

No issues found. The README doesn't expose any security vulnerabilities. The library properly:

• Uses transactions for consistency
• Validates event types before insertion
• Handles context cancellation to prevent resource exhaustion
• Uses safe key encoding without injection risks

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🎯 Code Quality (Underlying Implementation)

While reviewing the documentation, I also verified the implementation quality:

Strengths:

• Clean, idiomatic Go code
• Good use of BadgerDB transactions
• Proper error handling throughout
• Context support for cancellation
• Thread-safe operations with appropriate locking

Minor Observations:

• The TODOs in the codebase (query.go:27, 73-83, 79) are already documented in the README's "Further Development" section, which is good
• Test coverage appears comprehensive (separate test files for all major features)

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📊 Performance Considerations

The README accurately represents the indexing strategy. Consider adding a "Performance Tips" section:

• Use specific type filters when possible (single type uses optimized index)
• Place most selective tag first in queries (only first tag uses index currently)
• Set appropriate Limit values to prevent loading excessive events into memory
• For large aggregations with percentiles, be aware of the 1M value limit

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✅ Final Recommendations

Before merging:

1. Fix the aggregation example (show all results or request fewer)
2. Add error handling to export examples
3. Document retention CleanupInterval defaults
4. Consider adding a performance tips section
5. Consider adding context cancellation example
6. Consider documenting the 1M percentile limitation

Nice to have:

• Add a "Limitations" section
• Show more complete error handling patterns
• Clarify ULID string length is standard (not custom)

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Overall, this is excellent documentation for a well-designed library. The code examples are accurate and the structure is very user-friendly. The suggestions above are minor improvements that would make the documentation even more complete and helpful for new users.

Great work! 🎉