Update README: initial crawl + weekly delta DB policy

README.md

@@ -1,92 +1,99 @@
----
-pretty_name: pr0gramm user comments
-license: other
-language:
-- de
-- en
-task_categories:
-- other
----
-
-# pr0gramm-usercomments
-
-This dataset contains a SQLite export of pr0gramm item metadata and comments.
-
-Main file:
-
-- `pr0gramm.sqlite3`
-
-## Coverage
-
-The current snapshot is fully crawled up to item `6986879`.
-
-- Highest `items.item_id`: `6986879` (`created_at`: `2026-04-17 19:17:36 UTC`)
-- Highest `comments.item_id`: `6986879`
-
-## Tables
-
-The database contains:
-
-- `comments`
-- `items`
-
-### comments schema
-
-- `comment_id` INTEGER PRIMARY KEY
-- `item_id` INTEGER NOT NULL
-- `parent_comment_id` INTEGER
-- `comment_time` INTEGER
-- `score` INTEGER
-- `upvotes` INTEGER
-- `downvotes` INTEGER
-- `user_name` TEXT
-- `user_id` INTEGER
-- `user_profile_url` TEXT
-- `body` TEXT
-- `raw_json` TEXT NOT NULL
-
-### items schema
-
-- `item_id` INTEGER PRIMARY KEY
-- `promoted` INTEGER
-- `flags` INTEGER
-- `created_at` INTEGER
-- `user_name` TEXT
-- `source_feed` TEXT NOT NULL
-- `raw_json` TEXT NOT NULL
-
-## Example rows
-
-Example row from `comments`:
-
-```sql
-comment_id: 83842203
-item_id: 480055
-parent_comment_id: 0
-comment_time: 1776609541
-score: 1
-upvotes: 1
-downvotes: 0
-user_name: "1111111101"
-user_id: NULL
-user_profile_url: "https://pr0gramm.com/user/1111111101"
-body: "Damals war OC noch gut"
-raw_json (truncated): {"id":83842203,"parent":0,"content":"Damals war OC noch gut","created":1776609541,"up":1,"down":0,"confidence":0.206543,"name":"1111111101","mark":10}
-```
-
-Example row from `items`:
-
-```sql
-item_id: 6986879
-promoted: 0
-flags: 1
-created_at: 1776453456
-user_name: "Ometen"
-source_feed: "new"
-raw_json (truncated): {"id":6986879,"promoted":0,"userId":132720,"up":1,"down":0,"created":1776453456,"image":"2026/04/17/8804ec2d7b3e5297-h264-ultra_hd.mp4","thumb":"2026/04/17/8804ec2d7b3e5297.jpg",...}
-```
-
-## Notes
-
-- Timestamps are stored as Unix seconds.
-- `raw_json` contains API payload snapshots and may include fields not normalized into separate columns.
+---
+pretty_name: pr0gramm user comments
+license: other
+language:
+- de
+- en
+task_categories:
+- other
+---
+
+# pr0gramm-usercomments
+
+This dataset contains SQLite exports of pr0gramm item metadata and comments.
+
+## Initial Crawl
+
+The initial full snapshot is:
+
+- `pr0gramm.sqlite3`
+
+Initial full-crawl coverage:
+
+- Highest `items.item_id`: `6986879` (`created_at`: `2026-04-17 19:17:36 UTC`)
+- Highest `comments.item_id`: `6986879`
+
+## Weekly Delta DBs
+
+Incremental updates are published as additional SQLite files in the dataset root.
+
+Filename pattern:
+
+- `pr0_delta_YYYY-Www_ids_<upper>_<lower>.sqlite3`
+
+Meaning:
+
+- `<upper>` = highest crawled item id in that delta
+- `<lower>` = lowest crawled item id in that delta
+- IDs in a delta are crawled descending from `<upper>` to `<lower>`
+
+Delta crawl policy:
+
+- Weekly incremental crawl
+- Only IDs newer than the previous `last_known_id`
+- 14-day maturity delay before crawling (to capture most comments)
+- No revisit of older IDs in weekly mode
+
+Delta schema normalization:
+
+- Delta DBs are normalized to match the vacuumed base schema exactly.
+- Only tables: `items`, `comments`
+- No crawler-internal tables (for example `crawl_state`, `item_detail_failures`)
+
+## Merge Strategy
+
+To merge a delta into the base DB:
+
+1. Attach delta DB to a local copy of `pr0gramm.sqlite3`
+2. Upsert/insert by primary keys:
+   - `items.item_id`
+   - `comments.comment_id`
+
+Because IDs are monotonic and deltas are non-overlapping ranges, merge operations are straightforward and deterministic.
+
+## Tables
+
+The vacuumed schema is:
+
+- `comments`
+- `items`
+
+### comments schema
+
+- `comment_id` INTEGER PRIMARY KEY
+- `item_id` INTEGER NOT NULL
+- `parent_comment_id` INTEGER
+- `comment_time` INTEGER
+- `score` INTEGER
+- `upvotes` INTEGER
+- `downvotes` INTEGER
+- `user_name` TEXT
+- `user_id` INTEGER
+- `user_profile_url` TEXT
+- `body` TEXT
+- `raw_json` TEXT NOT NULL
+
+### items schema
+
+- `item_id` INTEGER PRIMARY KEY
+- `promoted` INTEGER
+- `flags` INTEGER
+- `created_at` INTEGER
+- `user_name` TEXT
+- `source_feed` TEXT NOT NULL
+- `raw_json` TEXT NOT NULL
+
+## Notes
+
+- Timestamps are stored as Unix seconds.
+- `raw_json` contains API payload snapshots and may include fields not normalized into separate columns.