Applies to Search provider: Microsoft Search Server
Crawls which have been running okay may suddenly appear to hang, or a newly registered site may not complete its crawl. The Central Administration Crawl History in the Crawl Log may show zero success. The Application Windows Log and the SharePoint ULS log (C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\LOGS) contain SQL-related errors; for example,
A database error occurred. Source: Microsoft SQL Server Native Client 10.0 Code: 8115 occurred 1 time(s) Description: Arithmetic overflow error converting expression to data type int. Context: Application 'Search_Service_Application'
The SQL error is caused by the value in a table exceeding the capacity of the int data type. Microsoft has addressed this issue in SharePoint Search Server 2010 SP1.
If you cannot install SP1, one workaround is to delete the Search Service Application, then recreate it and re-register the sites with Search Server.