Random access to cluster data may be faster, but full table scans on clustered tables are generally slower. Clusters renormalized the physical storage of tables without affecting the logical structure. ANSWER 3: An index-organized table is like a heap table with primary key index on one or more of its columns. However, instead of maintain two separated storage spaces for the table and a B-tree containing the primary key of the table and other column values. An overflow segment may exist due to the PCTTHRESHOLD value being set and the result of longer row lengths requiring the over flow area. Index-organized tables provide fast key-based access to table data for queries involving exact matches and range searches. Also, storage requirements are reduced because key columns are not duplicated in the table and index. The remaining non-key columns are stored in the index entry becomes very large; in that case, the DBMS server provides an OVERFLOW clause to handle the problem. ANSWER 4: An index can be partitioned and spread several tablespace. Each partition in the index corresponds to a segment and cannot span multiple tablespace. The primary use of a partitioned index is to minimize contention by spreading index I/O.
You've reached the end of your free preview.
Want to read all 6 pages?
- Spring '18
- Disk partitioning, cluster key