expend BDC 2000 records limit

using powershell command.

$bdcProxy = Get-SPServiceApplicationProxy | where {$_.GetType().FullName -eq ('Microsoft.SharePoint.BusinessData.SharedService.' + 'BdcServiceApplicationProxy')} 


$dbRule = Get-SPBusinessDataCatalogThrottleConfig -Scope Database -ThrottleType Items -ServiceApplicationProxy $bdcProxy  



$dbRule
you will see default setting like below.

Scope: Database
ThrottleType: Items
Enforced: True
Default : 2000
Max: 1000000


#Default and Maximum must be provided together. This increases the limit for external lists to 3000. Set-SPBusinessDataCatalogThrottleConfig -Identity $dbRule -Maximum 1000000 -Default 3000
#This disables a throttling rule. Notice the “:” instead of a space. Set-SPBusinessDataCatalogThrottleConfig -Identity $dbRule -Enforced:$false
#This enables a throttling rule. Set-SPBusinessDataCatalogThrottleConfig -Identity $dbRule -Enforced:$true



reference
http://blogs.msdn.com/b/bcs/archive/2010/02/16/bcs-powershell-introduction-and-throttle-management.aspx