how to rebuild sharepoint indexes what are the pros and cons

Assuming you are referring to SharePoint Search Indexes here; When you reset a index, you are emptying the index. Resetting crawled content deletes the content index and the property store. After a reset, search results will not be available until after crawls are run. You might want to reset an index under the following conditions: - You know or suspect that the index contains old data. - You know or suspect that the index contains corrupted data. - You have changed a great deal of content or several settings (for example, you have modified the rules for content sources) and you want to perform a full update to reflect those changes. - You realize that there is a problem with security, and users are able to view data to which they should not have access. Resetting the index immediately removes this data from their access. How to reset a crawled content/index http://technet.microsoft.com/en-us/library/cc262653(v=office.12).aspx My SharePoint Blog http://www.dhirendrayadav.com