About Updates to Indexed Columns

In releases prior to Oracle Database 12c Release 2 (12.2), when there is an update to the column on which an Oracle Text index is based, the document is unavailable for search operations until the index is synchronized. User queries cannot perform a search of this document. Starting with Oracle Database 12c Release 2 (12.2), you can specify that documents must be searchable after updates, without immediately performing index synchronization. Before the index is synchronized, queries use the old index entries to fetch the contents of the old document. After index synchronization, user queries fetch the contents of the updated document.

The ASYNCHRONOUS_UPDATE option for indexes enables you to retain the old contents of a document after an update and then use this index to answer user queries.

See Also: