DB INDEXSEQNO
DB_INDEXSEQNO
Class
Environment Variables / Symbols
Purpose
Used for data and character index optimization
See Also
Upgrading from pre-9.0 versions, INDEX, USE
Description
The DB_INDEXSEQNO environment variable / symbol environment variable has been added to help with optimizing character and date indexes. The optimization is based on the use of the pseudo column SYNCNUM to ensure that all keys are unique. Every row/record in a table has a unique SYNCNUM value for that table.
When DB_INDEXSEQNO is set to true, any tables and indexes that have not previously been converted, will be converted to use the SYNCNUM optimization as they are opened. It is however recommended that you use "dbconvert index" or "convert index" to manually convert your tables before setting DB_INDEXSEQNO to true.
New rows added to tables will always have the SYNCNUM column updated with a new unique number regardless of the DB_INDEXSEQNO setting. Once .dbx files have been converted to use SYNCNUM optimization, the DB_INDEXSEQNO value has no effect.
To disable SYNCNUM optimization after it has been enabled, you must set the value of DB_INDEXSQNO to false and then recreate all the index and tag files. Tag files will need to be recreated from scratch, so tables must be opened with USE