Slideshow:
Definition: clustering index
Common occurrence of a clustering index
Definition: non-clustering index
- Recall:
clustered and
non-clustered file
(see:
click here)
- Clustered file:
- A file that stores
records of
one relation
- A file that stores
records of
one relation
- Unclustered file:
(less common)
- A file that stores
records of
multiple relation
- A file that stores
records of
multiple relation
- Clustered file:
-
Clustering index
- An index on attribute(s) A on
a file is
a clustering index when:
- All tuples with attribute value A = a are stored sequentially (= consecutively) in the data file
Graphically:
- An index on attribute(s) A on
a file is
a clustering index when:
- Common example of a
clustering index:
- When the relation R is
sorted on
the attribute(s) A:
- When the relation R is
sorted on
the attribute(s) A:
- Non-clustering index:
- Non-clustering index =
an index that is
not clustering
- Non-clustering index =
an index that is
not clustering