Web Crawler
In this section, we present how to use a web crawler within MindsDB.
A web crawler is an automated script designed to systematically browse and index content on the internet. Within MindsDB, you can utilize a web crawler to efficiently collect data from various websites.
Prerequisites
Before proceeding, ensure the following prerequisites are met:
- Install MindsDB locally via Docker or Docker Desktop.
- To use Web Crawler with MindsDB, install the required dependencies following this instruction.
Connection
This handler does not require any connection parameters.
Here is how to initialize a web crawler:
The above query creates a database called my_web
. This database by default has a table called crawler
that stores data from a given URL or multiple URLs.
Usage
Parameters
Crawl Depth
The crawl_depth
parameter defines how deep the crawler should navigate through linked pages:
crawl_depth = 0
: Crawls only the specified page.crawl_depth = 1
: Crawls the specified page and all linked pages on it.- Higher values continue the pattern.
Page Limits
There are multiple ways to limit the number of pages returned:
- The
LIMIT
clause defines the maximum number of pages returned globally. - The
per_url_limit
parameter limits the number of pages returned for each specific URL, if more than one URL is provided.
Crawling a Single URL
The following example retrieves data from a single webpage:
Returns 1 row by default.
To retrieve more pages from the same URL, specify the LIMIT
:
Returns up to 30 rows.
Crawling Multiple URLs
To crawl multiple URLs at once:
Returns 3 rows by default (1 row per URL).
To apply a per-URL limit:
Returns 4 rows (2 rows per URL).
Crawling with Depth
To crawl all pages linked within a website:
Returns 1 + x rows, where x
is the number of linked webpages.
For multiple URLs with crawl depth:
Returns 2 + x + y rows, where x
and y
are the number of linked pages from each URL.
Get PDF Content
MindsDB accepts file uploads of csv
, xlsx
, xls
, sheet
, json
, and parquet
. However, you can also configure the web crawler to fetch data from PDF files accessible via URLs.
Configuring Web Handler for Specific Domains
The Web Handler can be configured to interact only with specific domains by using the web_crawling_allowed_sites
setting in the config.json
file.
This feature allows you to restrict the handler to crawl and process content only from the domains you specify, enhancing security and control over web interactions.
To configure this, simply list the allowed domains under the web_crawling_allowed_sites
key in config.json
. For example:
Troubleshooting
Web crawler encounters character encoding issues
- Symptoms: Extracted text appears garbled or contains strange characters instead of the expected text.
- Checklist:
- Open a GitHub Issue: If you encounter a bug or a repeatable error with encoding, report it on the MindsDB GitHub repository by opening an issue.
Web crawler times out while trying to fetch content
- Symptoms: The crawler fails to retrieve data from a website, resulting in timeout errors.
- Checklist:
- Check the network connection to ensure the target site is reachable.
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