MDAC 2.5 SDK - OLE DB Programmer's Reference
Chapter 11: Integrated Indexes
The visibility of pending changes in the index is governed by the same mechanisms that govern the visibility of pending changes in the base table, with one important difference: If an index column in a row is updated, this is considered to be the same as deleting that row from the index and inserting a new row with the new value. Therefore, the visibility of pending deletes for completely released and refetched rows depends on whether the rowset exposes IRowsetIdentity. The visibility in the index of pending inserts depends on DBPROP_RETURNPENDINGINSERTS. Pending updates to key columns might not appear in the correct position in the index until the update is transmitted to the data store.
The visibility in the index of transmitted changes is governed by the same mechanisms that govern the visibility of transmitted changes in the base table. In other words, it depends on the DBPROP_OWNUPDATEDELETE, DBPROP_OWNINSERT, and DBPROP_REMOVEDELETED properties.