MonetDB-RDF-SparQL meeting (26.11.2010)
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Participant List: Lefteris Niels Peter Sjoerd Stefan
- SparQL syntax & semantic basics
+ Lefteris: Support property paths! --- the code is basically there.
- Status report by Lefteris
+ RDF document shredding into 6 permutation of SPO triple table is done, incl. dictionary & tokenizer --- module bug fixes & performance tuning (multi-threaded) + support for multiple documents / incremental shredding is missing + RDF SQL schema contains GRAPHS table that lists existing documents and their SQL SPO table sets * Open: which is best storage (physical clustering/ordering) and most efficient use of that (sorted permutations + merge-joins; hash-tables + hash-joins, MLA + positional-join-index)
- Architecture alternatives
+ start with existing SparQL parser, e.g., redland librdf => SparQL algebra What are the SparQL algebra operators and what is the type system? + which relational algebra operators are required? + are polimorphic types / runtime typing & casting required? or can we make this explicit in the generated SQL query? (value constructing function, comparison functions, EBV, typed literals, ...) = S P O t s schema: S: oid -> tokenizer P: oid -> tokenizer O: oid/lng t: bte: uri: O=oid -> tokenizer str: O=oid -> s num: O=lng as is XML types? -> to be seen ... s: str (unique?) = exploit shredding order ("natural" MLA) = start with hash rather than permutations = support/exploit re-using hash tables with slices = recycler??
+ NULL semantics? + triple-valued booleans?
- SparQL syntax & semantics
(details, hurdles, etc.)