• Article Type: General
• Product: Aleph
• Product Version: 18.01

Description:
We're concerned that we're missing an index for TAB z01. In v18, does z01 have a z01_id6?

I didn't find one in .../aleph/tab/file_list.* and in the usmxx file_lists but there is one in .../alephm/sql_tab/, z01_create_index_6.sql. The .../aleph/tab/file_list.ADM and .../aleph/tab/file_list.BIB have just 4 indexes, z01_id, z01_id1-z01_id4 where the AUT, COURSE, ILL, HOL, and VIR file_lists have 5 indexes, z01_id, z01_id1-z01_id5.

Resolution:
Index z01_id6 is an index by Z01_REF_TYPE column, which is 1 character long and can have one of two values: blank or “U” (please see table structure description in tables documentation).

There is rarely a reason to build index on a field which can have only two values and probably will be never used by Oracle unless a specific hint to use it is given. In such case it even might slow down the queries.

The existence of the script in sql_tab directory does not disturb any functionality of ALEPH and, thus, does not need to be removed. You can just ignore it.

• Article last edited: 10/8/2013