The following table summarizes information about resource throttles and limits that you need to be aware of. These throttles and limits are set on the Resource Throttling page in Central Administration. Contact your administrator for specific limits and requests for your site.
NOTE   To assist with management, the administrator is not subject to the following resource throttles and limits.
or Limit
List View Threshold
Specifies the maximum number of list or library items that a database operation, such as a query, can process at one time. Operations that exceed this limit are blocked.
To give you time to make alternative plans, You are warned on the List Settings page when your list has exceeded 3,000 items. The warning contains a help link to this topic.
Unique permissions limit
Specifies the maximum number of unique permissions allowed for a list or library.
Every time you break the inheritance of permissions for an item or folder, it is counted as 1 unique permission toward this limit. If you try to add an item that would lead to exceeding this limit, you are prevented from doing so.
Row size limit
Specifies the maximum number of table rows internal to the database used for a list or library item. To accommodate wide lists with many columns, each item is wrapped over several internal table rows, up to 6 rows and up to a total of 8,000 bytes (excluding attachments).
For example, if you have a list with many small columns, one that contains hundreds of Yes/No columns, then you could exceed this limit, in which case you would not be able to add more Yes/No columns to the list, but you still may be allowed to add columns of a different type.
NOTE   Administrators can only set this limit by using the object model, not through the user interface.
List View Lookup Threshold
Specifies the maximum number of join operations, such as those based on lookup, Person/Group, or workflow status columns.
If the query uses more than eight columns, the operation is blocked. However, it is possible to programmatically select which columns to use by using maximal view, which can be set through the object model.
List View Threshold size for auditors and administrators
Specifies the maximum number of list or library items that a database operation, such as a query, can process at one time when performed by an auditor or administrator with appropriate permissions. This setting works in conjunction with Allow Object Model Override.
Allow Object Model Override
Specifies whether or not developers can perform database operations, such as queries, that request an override of the List View Threshold to the higher limit specified by the List View Threshold for auditors and administrators. An administrator must enable an object model override, and then developers with appropriate permission may then programmatically request that their query use the higher List View Threshold to take advantage of it.
Daily time window
Specifies a time period during which resource thresholds and limits are ignored. An administrator can configure a time window during “off-peak” hours in 15 minute increments and up to 24 hours, such as, 6:00 PM to 10:00 PM or 1:30 AM to 5:15 AM.
NOTE   A database operation or query started within the daily time window continues until completion (or failure) even if it doesn’t finish within the specified time window.