Estimating the size of spatial indexes

You can calculate the size of your spatial indexes based on the size of your spatial columns and dbspace overhead space size.

About this task

The ArcSDE service creates and maintains two indexes whenever you add a spatial column to one of your tables. The ArcSDE service creates an R-tree index on the spatial column and a B-tree index on the SE_ROW_ID INTEGER column. The R-tree index is named an_ix1 and the B-tree index is named a_n_ix2, where n is the spatial column's layer number assigned by the ArcSDE service.

The indexes are three percent greater than the dbspace overhead space and spatial column size of the table.

To calculate the index space requirements:

Procedure

  1. Combine the spatial column size and the dbspace overhead space size.
  2. Multiply this sum by the number of rows in the table.
  3. Multiply the result of step 2 by 1.03.