Microsoft Sharepoint Products and Technologies Resource Kit eBook

168 Part III: Planning and Deployment
The method used to update the index can have a significant effect on performance.
The following topics describe these four methods.
Full Update
During a full update, SharePoint Portal Server updates all content in a content index. A
full update of a content source includes adding new content, modifying changed content,
refreshing the content index for existing unchanged content, and removing
deleted content from the content index. This is the most time-consuming and resourceintensive
type of update, and it should be done only in the following situations:
■ If you create a new rule that affects only one content source.
■ If files are renamed in a specific content source.
■ If it is the first crawl of a content source.
■ If you include or exclude a new file type.
■ If permissions are changed on documents in the content source. While all
updates pick up permission changes, only the full updates pick up changes to
membership in local groups. This is why it is recommended that you not use
local groups to secure content that SharePoint Portal Server crawls.
■ If there is a power outage. In this case, SharePoint will want to run full
indexes to reset the index. It might be faster to reset the index files and clean
them out before running a full index. (Resetting the index files is discussed in
Chapter 22.)
■ If you change the noise word file.
■ If there is an area name change.
■ If you reset the content index.
Given all these changes that will force you to rerun a full index, it is best that
you plan for them so that the full indexes can be run without overloading either the
indexing server or the content source’s server.
Incremental Update
An incremental update of a content source includes only changed content. Share-
Point Portal Server does not remove deleted content from the content index and
does not recrawl unchanged content. For this reason, performing an incremental
update is faster than performing a full update.
You can perform an incremental update if you know that content has changed
but you do not want to perform a full update and you don’t mind having some
deleted content continue to appear in your index. A periodic incremental update
creates the index without using the time or resources required for a full update,
which enables you to perform a full update less frequently.