Re: Index length

Marco Pagan <marco.pagan_at_abb.it> wrote:
> Anyone could explain me how colculate the record length of an index ?

You can calculate the *average* length of an index key ... it's pretty easy.

analyze index OWNER.INDEX_NAME validate structure;

select * from index_stats;

The index_stats view will show you some vital statistics about the index you just validated. Pay attention to the LF_ROWS_LEN and the LF_ROWS.

LF_ROWS: Number of leaf rows in the index. LF_ROWS_LEN: Sum of the length of all leaf rows.

The average length of an index leaf row is therefore LF_ROWS_LEN / LF_ROWS. You also might want to consider the index /branch/ size, computed similarly with BR_ROWS_LEN / BR_ROWS ...

--
-brett neumeier