Publish Common Crawl shards 1-10

README.md

@@ -114,35 +114,29 @@ The following is an example row from the dataset:
   "url": "https://example.com/article/interesting-topic",
   "host": "example.com",
   "crawl_date": "2026-02-06T18:14:58Z",
-  "warc_type": "conversion",
   "warc_record_id": "<urn:uuid:a1b2c3d4-e5f6-7890-abcd-ef1234567890>",
   "warc_refers_to": "<urn:uuid:f9e8d7c6-b5a4-3210-fedc-ba0987654321>",
-  "content_type": "text/markdown",
   "html_length": 48210,
   "markdown_length": 3847,
   "warc_headers_json": "{\"Content-Length\": \"3847\", ...}",
-  "markdown": "# Interesting Topic\n\nThis is the main content of the page...",
-  "source_warc_file": "00000.md.warc.gz",
-  "source_file_index": 0
+  "markdown": "# Interesting Topic\n\nThis is the main content of the page..."
 }
 ```
 
 ### Data Fields
 
-- `doc_id` (string): unique identifier derived from the WARC-Record-ID (UUID format)
-- `url` (string): original URL of the crawled page
-- `host` (string): lowercase hostname extracted from the URL
-- `crawl_date` (string): RFC 3339 timestamp from the WARC record
-- `warc_type` (string): WARC record type, typically "conversion" for markdown output
-- `warc_record_id` (string): full WARC-Record-ID in the urn:uuid format
-- `warc_refers_to` (string): WARC-Record-ID of the original HTTP response record this was converted from
-- `content_type` (string): content type of the converted record (text/markdown)
-- `html_length` (int64): byte length of the original HTML body before conversion
-- `markdown_length` (int64): byte length of the converted markdown body
-- `warc_headers_json` (string): all WARC headers serialized as a JSON object with sorted keys, preserving every header from the packed record for full provenance
-- `markdown` (string): the cleaned markdown content extracted from the HTML page
-- `source_warc_file` (string): filename of the packed .md.warc.gz shard this record came from
-- `source_file_index` (int32): zero-based index of the source file in the crawl manifest
+| Column | Type | Description |
+|---|---|---|
+| `doc_id` | string | Unique identifier derived from the WARC-Record-ID (UUID) |
+| `url` | string | Original URL of the crawled page |
+| `host` | string | Lowercase hostname extracted from the URL |
+| `crawl_date` | string | RFC 3339 timestamp from the WARC record |
+| `warc_record_id` | string | Full WARC-Record-ID of the conversion record (`<urn:uuid:...>`) |
+| `warc_refers_to` | string | WARC-Record-ID of the original HTTP response this was converted from |
+| `html_length` | int64 | Byte length of the original HTML body before conversion |
+| `markdown_length` | int64 | Byte length of the converted markdown body |
+| `warc_headers_json` | string | All WARC headers as a sorted-key JSON object — full provenance in one column |
+| `markdown` | string | Clean markdown content extracted from the page |
 
 ### Data Splits
 
@@ -170,6 +164,21 @@ The processing pipeline runs in five stages:
 
 Empty conversions (pages where trafilatura could not extract meaningful content) are dropped.
 
+### Compression Ratios
+
+The pipeline achieves aggressive size reduction at every stage. Numbers below are measured from shard `00000` of CC-MAIN-2026-08 (~21,000 pages), and projected to the full crawl.
+
+| Stage | Per shard | Projected (100,000 shards) | Reduction |
+|---|---|---|---|
+| Raw WARC (.warc.gz, downloaded) | ~830 MB | ~83 TB | — |
+| HTML extracted (uncompressed) | 2.7 GB | ~270 TB | — |
+| Packed markdown WARC (.md.warc.gz) | 36.3 MB | ~3.6 TB | **-97.8%** vs raw WARC |
+| Final Parquet (ZSTD level 19) | 27.9 MB | ~2.8 TB | **-23%** vs packed WARC |
+
+The big win happens in the HTML → Markdown conversion step: trafilatura strips all HTML tags, inline scripts, stylesheets, navigation elements, footers, and ads, keeping only the main content. This cuts the uncompressed text from 2.7 GB to 79 MB per shard — a **97.2% reduction** — before any file-level compression is applied.
+
+Parquet with Zstd level 19 then adds another 23% on top of the already-compressed WARC gzip. End to end, one raw WARC shard of ~830 MB becomes a 27.9 MB Parquet file containing ~21,000 clean markdown documents.
+
 ### Personal and Sensitive Information
 
 No additional PII filtering is applied beyond what Common Crawl provides. As the dataset is sourced from the public web, it is likely that some personally identifiable information is present. If you find your own PII in the dataset and would like it removed, please open an issue on the repository.

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