Tasks & Planning
SPARQL Algebra Duc, Lefteris
SPARQL to Relational(sql) Algebra Niels, Peter, Lefteris
RUNTIME Enviroment (shredder and functions) Lefteris, Peter
Code Management - Module Maintenance - Packaging Sjoerd
MonetDB-RDF-SparQL meeting (26.11.2010)
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.)
MonetDB-RDF-SparQL meeting (10.03.2011)
CWI: Lefteris, Niels, Peter, Sjoerd, Duc
UOA: Babis, Mixalis, Kostis, by spirit Manolis
- Brought up to date the members of UOA on the MonetDB/RDF ideas.
- Talked about self referenced triples (TIDs)
- Incorporating spatial (and temporal) data
- TID (triples ID)
- Each triple has an ID, its position on the triple table, referred to hereafter as TID
- Statements about triples can be made using the TID of the form (TID,property,object)
- The most significant bit of the t byte if set then the triple has the form of (TID,property,object)
- The rest 7 bits of t are left for typing the object
- Two 32 bit integers [latitude,longitude] concatenated into one 64bit int appearing only as object
- A spatial type is defined on the t byte
- Zone / Clustering Index on the spatial data
NKUA RDF Meeting (21.03.2011)
Participant List: Babis, Kostis, Manolis, Michael, and Stavros
RDF Development Plan on MonetDB
- Port Strabon on MonetDB using JDBC and geoss library.
- Extend (1) by developing an RDF storage scheme in Monet and producing appropriate SQL code for that scheme which evaluates given SPARQL queries.
- Extend current RDF storage scheme developed by Lefteris, or SPOts (if available) with spatial data.
- Modification of the Sesame's parser to produce appropriate SQL code for the employed RDF storage scheme, or development of a SPARQL interface from scratch possibly using the parser that Sjoerd is producing.
- Discard geoss library and implement (some of?) the respective spatial functions in Monet (inside the kernel).