Transformation Catalogue

This is a living document listing implementations of AST and algebra transformations powered by Traqula.

Ast transformations

1. Default pretty and compact print through Traqula generators (for SPARQL 1.1 and SPARQL 1.2).

Algebra transformations

1. Comunica: assign source: Assign to each triple pattern or path what source it should be queried from.
2. Comunica: Bgp to join: Transform a Bgp to a join of triple patterns.
3. Comunica: construct distinct: Wrap the construct operator in a distinct, ensuring the bag of triples becomes a set.
4. Comunica: describe to construct: transform a describe query to a union of construct describing the various terms to be described.
5. Comunica: filter pushdown: transforms the query to push down filter expressions into the query plan as deep as possible.
6. Comunica: join BGPs: merges a join of BGPs into a single BGP.
7. Comunica: join connected: join reordering based on variable connectivity
8. Comunica: left join expression pushdown: Given a leftJoin expression, it pushes down associated filter expressions in case they only target one of the two branches.
9. Comunica: prune empty sources: Remove operations that are guaranteed to produce empty result based on the underlying datasource.
10. Comunica: rewrite add, copy, move: Rewrite add, copy and move to delete/insert.
11. GraphQl to SPARQL: Rewrite blank nodes inside the query to variables.