Prioritize certain traversal paths with content policies

[rubensworks]

Issue type:

• :heavy_plus_sign: Feature request

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Description:

For the following query, the query engine could somehow make use of prior knowledge that movie and watch data exists in the same file:

https://comunica.github.io/comunica-feature-link-traversal-web-clients/builds/solid-default/#datasources=https%3A%2F%2Fdrive.verborgh.org%2Fmovies%2F&query=PREFIX%20schema%3A%20%3Chttps%3A%2F%2Fschema.org%2F%3E%0ASELECT%20*%20WHERE%20%7B%0A%20%20%3Fmovie%20a%20schema%3AMovie.%0A%20%20%3Faction%20a%20schema%3AWatchAction%3B%0A%20%20%20%20%20%20%20%20%20%20schema%3Aobject%20%3Fmovie.%0A%7D&solidIdp=https%3A%2F%2Fdrive.verborgh.org%2F

This prior knowledge could be captured in content policies, which could either be predefined (e.g. via shapetrees), or learned dynamically via prior query executions. The next step is then to incorporate these content policies during query execution, for both prioritization and discovery.

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One concrete use case is the prioritization of type index links over others, which could be useful for this query: https://comunica.github.io/comunica-feature-link-traversal-web-clients/builds/solid-default/#transientDatasources=https%3A%2F%2Frubensworks.solidcommunity.net%2Fprofile%2Fcard&query=PREFIX%20bookm%3A%20%3Chttp%3A%2F%2Fwww.w3.org%2F2002%2F01%2Fbookmark%23%3E%0ASELECT%20*%20WHERE%20%7B%0A%20%20%3Fbookmark%20a%20bookm%3ABookmark%3B%0A%20%20%20%20bookm%3AhasTopic%20%3Ftopic.%0A%7D

[github-actions[bot]]

Thanks for the suggestion!

[rubensworks]

At the time of writing, the query doesn't work anymore due to a change in the underlying dataset.