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README.md
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│ ├── analysis_report_2005.txt
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│ └── ...
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│
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├── subreddits_2025-01_* # Subreddit metadata (January 2025 snapshot)
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│ ├── type_public.jsonl # 2.78M public subreddits
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│ ├── type_restricted.jsonl # 1.92M restricted subreddits
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│ ├── type_private.jsonl # 182K private subreddits
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- **Categorization:** Subreddit type classification
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- **Timestamps:** Unix epoch seconds
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## 🎯 Research Applications
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### Community Studies
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│ ├── analysis_report_2005.txt
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│ └── ...
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│
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├── subreddits_2025-01_* # Subreddit metadata (currently old January 2025 snapshot)
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│ ├── type_public.jsonl # 2.78M public subreddits
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│ ├── type_restricted.jsonl # 1.92M restricted subreddits
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│ ├── type_private.jsonl # 182K private subreddits
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- **Categorization:** Subreddit type classification
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- **Timestamps:** Unix epoch seconds
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## 🔧 Technical Design Decisions
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### Compression Strategy: Why ZST → JSONL → Parquet?
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This pipeline employs a tiered compression strategy based on access patterns:
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#### **Original Archives (ZST Compressed)**
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- **Format:** `.zst` (Zstandard) compressed JSONL
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- **Why ZST?** 6:1 compression ratio (36GB → 6GB) vs gzip's 4:1
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- **Trade-off:** 39.7s decompression time vs 26.8s raw read
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- **Decision:** Keep only for archival; decompress once to JSONL
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#### **Analytical Storage (Parquet)**
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- **Format:** Apache Parquet with zst compression
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- **Why Parquet?** Columnar storage enables:
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- Selective column reads (read 2/17 columns = 15s vs 55s)
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- Built-in compression (36GB → 7GB = 5:1 ratio)
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- Predicate pushdown (skip irrelevant rows)
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- **Benchmark:** Metadata read in 4.9s vs 26.8s JSONL read
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## ⚡ Performance Benchmarks
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### File Processing Speeds (36GB Reddit Comments, Nov 2016)
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| Format | Size | Read Time | Compression | Notes |
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|--------|------|-----------|-------------|-------|
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| **ZST Compressed** | 6.0GB | 39.7s | 6:1 | Requires decompression penalty |
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| **JSONL Raw** | 36GB | 26.8s | 1:1 | Fastest for repeated access |
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| **Parquet** | 7.0GB | 4.9s* | 5:1 | Metadata only; queries 2-15s |
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## 🎯 Research Applications
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### Community Studies
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