c73e43f5c9
In the scenario where an operator * Performs a new crawl from spec * Doesn't load the data into the index * Recrawls the data The recrawl will not find the domains in the database, and the crawl log will be overwritten with an empty file, irrecoverably losing the crawl log making it impossible to load! To mitigate the impact similar problems, the change saves a backup of the old crawl log, as well as complains about this happening. More specifically to this exact scenario however, the parquet-loaded domains are also preemptively inserted into the domain database at the start of the crawl. This should help the DbCrawlSpecProvider to find them regardless of loaded state. This may seem a bit redundant, but losing crawl data is arguably the worst type of disaster scenario for this software, so it's arguably merited. |
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|---|---|---|
| .. | ||
| converting-process | ||
| crawling-process | ||
| index-constructor-process | ||
| loading-process | ||
| test-data | ||
| website-adjacencies-calculator | ||
| readme.md | ||
Processes
1. Crawl Process
The crawling-process fetches website contents, temporarily saving them as WARC files, and then re-converts them into parquet models. Both are described in crawling-model.
The operation is optionally defined by a crawl specification, which can be created in the control GUI.
2. Converting Process
The converting-process reads crawl data from the crawling step and processes them, extracting keywords and metadata and saves them as parquet files described in processed-data.
3. Loading Process
The loading-process reads the processed data.
It has creates an index journal, a link database, and loads domains and domain-links into the MariaDB database.
4. Index Construction Process
The index-construction-process constructs indices from the data generated by the loader.
Overview
Schematically the crawling and loading process looks like this:
+-----------+
| CRAWLING | Fetch each URL and
| STEP | output to file
+-----------+
|
//========================\\
|| Parquet: || Crawl
|| Status, HTML[], ... || Files
|| Status, HTML[], ... ||
|| Status, HTML[], ... ||
|| ... ||
\\========================//
|
+------------+
| CONVERTING | Analyze HTML and
| STEP | extract keywords
+------------+ features, links, URLs
|
//==================\\
|| Parquet: || Processed
|| Documents[] || Files
|| Domains[] ||
|| Links[] ||
\\==================//
|
+------------+ Insert domains into mariadb
| LOADING | Insert URLs, titles in link DB
| STEP | Insert keywords in Index
+------------+
|
+------------+
| CONSTRUCT | Make the data searchable
| INDEX |
+------------+