This analysis enables you to determine the degree of disorganization in the storage conditions for cluster keys and clustering data pages, so that you can decide whether or not the database needs to be reorganized.
The following shows the results of cluster key and clustering data page storage condition analysis:
pddbst VV-RR(Object Option) ** Index Status Analysis ** 2001/08/22 16:44:01 [1] |
Table 15-7 Results of cluster key and clustering data page condition analysis and actions to be taken describes the results of cluster key and clustering data page condition analysis and explains the actions to be taken.
Note that row deletion has no effect on the degree of irregularity in the clustering data conditions in the analysis results. If deletion is the principal table operation performed, you must take the following steps to determine whether or not the database needs to be reorganized:
For 2, the following shows the size of the invalid free area:
(Current number of used pages in table#1 - number of table storage pages#2) page size (bytes)
#1: Obtain the value from the results of condition analysis by table.
#2: To obtain the value, see the HiRDB Version 9 Installation and Design Guide.
Table 15-7 Results of cluster key and clustering data page condition analysis and actions to be taken
Target | Analysis result | Description and action |
---|---|---|
Cluster keys | There are too many rows for the number of storage keys in the index. | The key duplication ratio is high, affecting the performance of search operations that use the index. Check and, if necessary, revise the column structure in the index definition. |
There are keys that are stored in a duplicate key structure.#1 | Some keys have (or had) a high degree of duplication, affecting the performance of search operations that use the index. Check and, if necessary, revise the column structure in the index definition (if this condition existed in the past, you can eliminate the duplicate key structure by using pdrorg to reorganize the index).#2 | |
Degree of irregularity is high in the storage order. | There is irregularity in the storage order, which is affecting search performance. Use pdrorg to reorganize the index. If there is irregularity also in the storage order of data pages, reorganizing the table will automatically reorganize the index. | |
Clustering data pages | Degree of irregularity is high in the storage order. | There is irregularity in the storage order of data pages, which is affecting the performance of access operations in the order of cluster key values. Use pdrorg to reorganize the table. |
The following condition is true: Storage location changes count > storage location changes count or number of used segments in the results of condition analysis by table > number of pages - 1 |