A RowNumExpr in GProM generates an identifier (number starting from 1) for each row of the projection it is used in. In Oracle this is directly supported by using special attribute ROWNUM in the SELECT clause of a query. For other databases we would have to translate this into ROW_NUMBER OVER() (i.e., a window function). This could be implemented in the serializer as a preprocessing step that introduces a new window operator (which is safer) or in the expression serialization which could be unsafe in corner cases (if RowNumExpr is used in the same SELECT clause as an aggregation).
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RowNumExprin GProM generates an identifier (number starting from 1) for each row of the projection it is used in. In Oracle this is directly supported by using special attributeROWNUMin theSELECTclause of a query. For other databases we would have to translate this intoROW_NUMBER OVER()(i.e., a window function). This could be implemented in the serializer as a preprocessing step that introduces a new window operator (which is safer) or in the expression serialization which could be unsafe in corner cases (ifRowNumExpris used in the sameSELECTclause as an aggregation).