This hotfix also applies to Microsoft SQL Server 2012 Reporting Services (SSRS 2012) and SQL Server 2014 Reporting Services (SSRS 2014).
You cannot input text that has more than 32,767 characters in any textboxes in the Report Query Designer in Microsoft SQL Server 2008 R2 Business Intelligence Development Studio (BIDS), SQL Server 2012 SQL Server Data Tools (SSDT), or SQL Server 2014 SQL Server Data Tools (SSDT). For example, assume that you try to create a new dataset. You use query designer, and you choose the Edit as Text option to input the query. In this situation, you cannot input a long query that has more than 32,767 characters.
This issue occurs because textboxes use the default setting of the TextBox.MaxLength property in Report Query Designer, which is 32,767 characters.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.