Abstract
A simple characterization of independent database schemes is proved. An algorithm is given for translating a tableau T, posed as a query on a representative instance, to a union of tableaux that is equivalent to T, but can be applied directly to database relations. The algorithm may take exponential time 1991, and it is applicable only to independent database schemes. If T is a just a projection of a representative instance, then the algorithm has a simpler form (which is still exponential in the worst case) and is polynomial in some cases.
| Original language | English |
|---|---|
| Pages (from-to) | 120-161 |
| Number of pages | 42 |
| Journal | Journal of the ACM |
| Volume | 38 |
| Issue number | 1 |
| DOIs | |
| State | Published - 1 Mar 1991 |
Keywords
- chase
- expanded cover
- extension join
- functional dependency
- independent database scheme
- join dependency
- lossless join
- null value
- query evaluation
- relational algebra
- relational database
- representative instance
- restricted projection
- tableau
- union of tableaux