Optimizing the Index

The CONTEXT index is an inverted index where each word contains the list of documents that contain that word. For example, after a single initial indexing operation, the word DOG might have the following entry:

DOG DOC1 DOC3 DOC5

Frequent index synchronization ultimately causes fragmentation of your CONTEXT index. Index fragmentation can adversely affect query response time. Therefore, to reduce fragmentation and index size and to ensure optimal query performance, allow time to optimize your CONTEXT index.

To schedule an auto optimize job, you must explicitly set STAGE_ITAB_MAX_ROWS to 0 to disable the automatic merging that now happens with SYNC_INDEX.

To optimize an index, Oracle recommends that you use CTX_DDL.OPTIMIZE_INDEX. To understand index optimization, you must understand the structure of the index and what happens when it is synchronized. This section contains the following topics:

• Index Fragmentation

• Document Invalidation and Garbage Collection

• Single Token Optimization

• Viewing Index Fragmentation and Garbage Data

See Also: Oracle Text Reference for the CTX_DDL.OPTIMIZE_INDEX statement syntax and examples