Can't identify or select unversioned data in ArcMap

I have a feature class that is not versioned as it is updated via DML statements that use data from a different software package. The DML statements, which simply update two columns, process fine, the feature class displays just fine in ArcMap, but when I try to identify, I get no results. When I try to select, I get an ORA-01455, "The converted form of the specified expression was too large for the specified datatype". What on earth is going on, and how do I fix it? Thanks.