Starting an Adaptive Update of a Content Index

An adaptive update, like the incremental update, crawls only the content that has changed since the previous update. Unlike the incremental update, however, the adaptive update increases its efficiency by attempting to access only those documents determined likely to have changed based on an analysis of historical information.

The adaptive update uses information accumulated over all previous updates of any type. The efficiency of the system increases over time and over multiple updates because more statistical samples are available to the algorithm. After a week of daily adaptive updates, the system settles into a steady state. A steady state is a state in which the system has acquired enough information so that the adaptive update is functioning at optimal efficiency.

The updates compute statistical information regardless of the type of update Microsoft Office SharePoint Portal Server 2003 performs. You can perform incremental updates and then later switch to adaptive updates. Performance improves immediately because the system is already in a steady state. This means that SharePoint Portal Server has already accumulated sufficient statistical information to apply the algorithm. Use of an adaptive update is unlikely to give a significant performance improvement in collections of fewer than 2,500 documents.

Important   An adaptive update is faster than an incremental or full update, but an adaptive update could miss some updated content. However, SharePoint Portal Server always crawls documents that have not changed for two weeks, so no changes would go unnoticed for longer than that.

Performance improvement between an adaptive update and an incremental update depends on the number of documents and the frequency of changes to the documents. The higher the percentage of documents that change infrequently, the better the performance is.

If you have not performed any other updates, the first time you perform an adaptive update is equal to performing a full update, and the second time you perform an adaptive update is equal to performing an incremental update. You see the first improvement the third time you perform an adaptive update.

If power to the server is interrupted during an update, the update continues after power is restored. The index is in the "initializing" state for a certain period of time, which depends on the size of the crawl. The crawl resumes after it finishes initializing. The index is available for queries during this time.

In the server farm configuration, SharePoint Portal Server automatically propagates one or more indexes from index management servers to search (destination) servers after creating or updating an index.

You can start an adaptive update only if the update status is Idle. You can view the update status in the Update Status column for the index on the Configure Search and Indexing page. The update status can have the following values:

• Idle
• Crawling
• Crawling Adaptively
• Crawling Incrementally
• Paused (by user)
• Paused (disk full)
• Merging
• Propagating

Start an adaptive update of a content index

1. On the Site Settings page, in the Manage Search Settings and Indexed Content section, click Configure search and indexing.
2. On the Configure Search and Indexing page, in the Content Indexes section, click Manage the list of indexes.
3. On the Manage Content Indexes page, rest the pointer on the index name, and then click the arrow that appears.
4. On the menu that appears, click Adaptive Update.

You can schedule automatic updates of an index. For more information, see Creating a Search Schedule.