Fix to support composite key columns (GroupByColumns) in StatExtractor.

This update resolves an issue in StatExtractor where an error occurred during the extraction of relationship statistics when one of the columns in the relationship was part of a composite key (GroupByColumns). The error message was: "Column [] is part of composite key, but not all columns of the composite key are included in the expression or its dependent expression." This fix applies only to models with a compatibility level of 1200 or higher, as GroupByColumns is not available in levels 1100 and 1103.

Author: albertospelta

src/Dax.Model.Extractor/StatExtractor.cs

@@ -91,10 +91,10 @@ private void LoadRelationshipStatistics(int sampleRows = 0,bool analyzeDirectQue
 CALCULATETABLE (
 ROW( 
     ""RelationshipId"", {rel.Dmv1200RelationshipId},
-    ""MissingKeys"", DISTINCTCOUNT ( {EscapeColumnName(rel.FromColumn)} ),
+    ""MissingKeys"", {DistinctCountExpression(rel.FromColumn)},
     ""InvalidRows"", COUNTROWS({EscapeTableName(rel.FromColumn.Table)})
 ),
-ISBLANK( {EscapeColumnName(rel.ToColumn)} ),
+{IsBlankExpression(rel.ToColumn)},
 USERELATIONSHIP( {EscapeColumnName(rel.FromColumn)}, {EscapeColumnName(rel.ToColumn)} )
 )").ToArray());
                 //             ""Column"", ""{EmbedNameInString(rel.FromColumn.ColumnName.Name)}"", 
@@ -138,11 +138,11 @@ private void LoadRelationshipStatistics(int sampleRows = 0,bool analyzeDirectQue
                         relationshipSet.Select(rel => (rel.MissingKeys > sampleRows && rel.MissingKeys <= MAX_KEYS_FOR_SAMPLE) ?
 $@"CALCULATETABLE ( 
 SELECTCOLUMNS ( 
-    SAMPLE ( {sampleRows}, DISTINCT ( {EscapeColumnName(rel.FromColumn)} ), {EscapeColumnName(rel.FromColumn)}, ASC ), 
+    SAMPLE ( {sampleRows}, {DistinctExpression(rel.FromColumn)}, {EscapeColumnName(rel.FromColumn)}, ASC ), 
     ""RelationshipId"", {rel.Dmv1200RelationshipId}, 
     ""MissingValue"", {EscapeColumnName(rel.FromColumn)} 
 ),
-ISBLANK( {EscapeColumnName(rel.ToColumn)} ),
+{IsBlankExpression(rel.ToColumn)},
 USERELATIONSHIP( {EscapeColumnName(rel.FromColumn)}, {EscapeColumnName(rel.ToColumn)} )
 )"
 : (DaxModel.CompatibilityLevel >= 1200) ?
@@ -155,7 +155,7 @@ private void LoadRelationshipStatistics(int sampleRows = 0,bool analyzeDirectQue
     ""RelationshipId"", {rel.Dmv1200RelationshipId}, 
     ""MissingValue"", {EscapeColumnName(rel.FromColumn)} 
 ))),
-ISBLANK( {EscapeColumnName(rel.ToColumn)} ),
+{IsBlankExpression(rel.ToColumn)},
 USERELATIONSHIP( {EscapeColumnName(rel.FromColumn)}, {EscapeColumnName(rel.ToColumn)} )
 )"
 :
@@ -237,15 +237,51 @@ private static string EscapeTableName(Table table)
 
         private static string DistinctCountExpression(Column column)
         {
-            // We always use COUNTROWS(ALLNOBLANKROW(t[c])) instead of DISTINCTCOUNT(t[c]) because it is compatible with GroupByColumns settings, such as Fields Parameters. 
-            // COUNTROWS(ALLNOBLANKROW()) always reads the list of values from the attribute hierarchy (when AvailableInMDX=true) or queries the table if the hierarchy is not available (when AvailableInMDX=false)
+            var columnName = EscapeColumnName(column);
+
+            if (column.GroupByColumns.Count == 0) {
+                return $"DISTINCTCOUNT({columnName})";
+            }
+            else {
+                // COUNTROWS(ALLNOBLANKROW(t[c])) is compatible with GroupByColumns settings like Fields Parameters because it always retrieves the list of
+                // values from the attribute hierarchy (when AvailableInMDX=true), or queries the table if the hierarchy is unavailable (AvailableInMDX=false).
+                return $"COUNTROWS(ALLNOBLANKROW({columnName}))";
+            }
+        }
+
+        private static string DistinctExpression(Column column)
+        {
+            var columnName = EscapeColumnName(column);
 
-            return $"COUNTROWS(ALLNOBLANKROW({EscapeColumnName(column)}))";
+            if (column.GroupByColumns.Count == 0) {
+                return $"DISTINCT({columnName})";
+            }
+            else {
+                var groupingColumnNames = string.Join(", ", column.GroupByColumns.Select((cn) => EscapeColumnName(column.Table, cn)));
+                var tableName = EscapeTableName(column.Table);
+                return $"DISTINCT(SELECTCOLUMNS(SUMMARIZE({tableName}, {columnName}, {groupingColumnNames}), {columnName}))";
+            }
         }
 
+        private static string IsBlankExpression(Column column)
+        {
+            var columnName = EscapeColumnName(column);
+
+            if (column.GroupByColumns.Count == 0) {
+                return $"ISBLANK({columnName})";
+            }
+            else {
+                var groupingColumnNames = string.Join(", ", column.GroupByColumns.Select((cn) => EscapeColumnName(column.Table, cn)));
+                return $"FILTER(ALL({columnName}, {groupingColumnNames}), ISBLANK({columnName}))";
+            }
+        }
         private static string EscapeColumnName(Column column)
         {
-            return $"{EscapeTableName(column.Table)}[{column.ColumnName.Name.Replace("]", "]]")}]";
+            return EscapeColumnName(column.Table, column.ColumnName);
+        }
+        private static string EscapeColumnName(Table table, DaxName columnName)
+        {
+            return $"{EscapeTableName(table)}[{columnName.Name.Replace("]", "]]")}]";
         }
         private static string EmbedNameInString(string originalName)
         {