INDEXSTATISTICS 
Definition
The statistics system table INDEXSTATISTICS contains information about the structure and sizes of indexes.
Structure
INDEXSTATISTICS
SCHEMANAME |
CHAR(32) |
Name of the schema of the table |
OWNER |
CHAR(32) |
Name of the owner of the table |
TABLENAME |
CHAR(32) |
Name of the table |
INDEXNAME |
CHAR(32) |
Index name (NULL for unnamed indexes) |
COLUMNNAME |
CHAR(32) |
Name of an inverted column |
DESCRIPTION |
CHAR(40) |
Description of how to interpret the following columns (see DESCRIPTION Column table) |
CHAR_VALUE |
CHAR(12) |
Alphanumeric value |
NUMERIC_VALUE |
FIXED(10) |
Numeric value |
DESCRIPTION Column
Value |
Explanation |
Root pno |
NUMERIC_VALUE contains the page number of the B* tree root |
File type |
CHAR_VALUE contains the B* tree type |
Used pages |
NUMERIC_VALUE contains the number of pages used by the index |
Index pages |
NUMERIC_VALUE contains the number of B* tree index pages used by the index |
Leaf pages |
NUMERIC_VALUE contains the number of leaf pages used by the index |
Index levels |
NUMERIC_VALUE contains the number of B* tree index levels |
Space used in all pages(%) |
NUMERIC_VALUE contains the percentage of the B* tree root pages used |
Space used in root page(%) |
NUMERIC_VALUE contains the percentage of the B* tree root pages used |
Space used in index pages(%) |
NUMERIC_VALUE contains the percentage of the B* tree index pages used |
Space used in index pages(%) min |
NUMERIC_VALUE contains the minimum percentage of the B* tree index pages used |
Space used in index pages(%) max |
NUMERIC_VALUE contains the maximum percentage of the B* tree index pages used |
Space used in leaf pages(%) |
NUMERIC_VALUE contains the percentage of the B* tree leaf pages used |
Space used in leaf pages(%) min |
NUMERIC_VALUE contains the minimum percentage of the B* tree leaf pages used |
Space used in leaf pages(%) max |
NUMERIC_VALUE contains the maximum percentage of the B* tree leaf pages used |
Secondary keys (index lists) |
NUMERIC_VALUE contains the number of different values in the indexed columns |
Avg secondary key length |
NUMERIC_VALUE contains the average length of the index values |
Min secondary key length |
NUMERIC_VALUE contains the minimum length of the index values |
Max secondary key length |
NUMERIC_VALUE contains the maximum length of the index values |
Avg separator length |
NUMERIC_VALUE contains the average length of a B* tree separator |
Min separator length |
NUMERIC_VALUE contains the minimum length of the separator |
Max separator length |
NUMERIC_VALUE contains the maximum length of the separator |
Primary keys |
NUMERIC_VALUE contains the number of rows in the tables identified by OWNER and TABLENAME |
Avg primary keys per list |
NUMERIC_VALUE contains the average number of keys per inversion list |
Min primary keys per list |
NUMERIC_VALUE contains the minimum number of keys per inversion list |
Max primary keys per list |
NUMERIC_VALUE contains the maximum number of keys per inversion list |
Values with selectivity <= 1% |
NUMERIC_VALUE contains the number of inversion lists with a selectivity <= 1% |
Values with selectivity <= 5% |
NUMERIC_VALUE contains the number of inversion lists with a selectivity between 1% and 5% |
Values with selectivity <= 10% |
NUMERIC_VALUE contains the number of inversion lists with a selectivity between 5% and 10% |
Values with selectivity <= 25% |
NUMERIC_VALUE contains the number of inversion lists with a selectivity between 10% and 25%. |
Values with selectivity > 25% |
NUMERIC_VALUE contains the number of inversion lists with a selectivity > 25% |
See also:
Concepts of the Database System, Logical Access Structures