20 | | ||case1 || 0||0||0||0|| 0|| |
| 24 | ||case1 || 27010||0||0||0|| 0|| |
| 25 | |
| 26 | |
| 27 | |
| 28 | * Analysis: |
| 29 | 1. When doing queries, ADERIS firstly queries each data sources using SPARQL to find out the |
| 30 | number of distinct predicate values(Data about subjects/objects not retrieved.) |
| 31 | select distinct ?p where { ?s ?p ?o }; |
| 32 | select count(?p) where { ?s ?p ?o }; |
| 33 | |
| 34 | potential consequences: |
| 35 | Without using caches and any metadata information pre-fetched, the system query each endpoint in real time, |
| 36 | which could take a long time, especially, when the number of endpoints increases. |
| 37 | |
| 38 | 2. |
| 39 | |
| 40 | |
| 41 | |
| 42 | |
| 43 | |
| 44 | |