sourceColumn

elide-datastore/elide-datastore-aggregation/src/main/java/com/yahoo/elide/datastores/aggregation/QueryEngine.java

@@ -111,6 +111,8 @@ private void populateMetaData(MetaDataStore metaDataStore) {
         metaDataStore.getModelsToBind().stream()
                 .map(model -> constructTable(model, metadataDictionary))
                 .forEach(metaDataStore::addTable);
+
+        metaDataStore.resolveSourceColumn();
     }
 
     /**

elide-datastore/elide-datastore-aggregation/src/main/java/com/yahoo/elide/datastores/aggregation/metadata/MetaDataStore.java

@@ -6,6 +6,7 @@
 package com.yahoo.elide.datastores.aggregation.metadata;
 
 import com.yahoo.elide.core.EntityDictionary;
+import com.yahoo.elide.core.Path;
 import com.yahoo.elide.core.datastore.inmemory.HashMapDataStore;
 import com.yahoo.elide.core.exceptions.DuplicateMappingException;
 import com.yahoo.elide.datastores.aggregation.AggregationDataStore;
@@ -169,4 +170,24 @@ public static boolean isMetricField(EntityDictionary dictionary, Class<?> cls, S
     public static boolean isTableJoin(Class<?> cls, String fieldName, EntityDictionary dictionary) {
         return dictionary.getAttributeOrRelationAnnotation(cls, Join.class, fieldName) != null;
     }
+
+    /**
+     * Resolve source columns for all Columns in all Tables.
+     */
+    public void resolveSourceColumn() {
+        getMetaData(Table.class).forEach(table ->
+                table.getColumns().forEach(column -> {
+                    Path sourcePath = column.getSourcePath(dictionary);
+                    Path.PathElement source = sourcePath.lastElement().get();
+
+                    Table sourceTable = (Table) dataStore.get(Table.class)
+                            .get(dictionary.getJsonAliasFor(source.getType()));
+
+                    Column sourceColumn = column instanceof Metric
+                            ? sourceTable.getMetric(source.getFieldName())
+                            : sourceTable.getDimension(source.getFieldName());
+                    column.setSourceColumn(sourceColumn);
+                })
+        );
+    }
 }

elide-datastore/elide-datastore-aggregation/src/main/java/com/yahoo/elide/datastores/aggregation/metadata/models/Column.java

@@ -8,13 +8,15 @@
 import com.yahoo.elide.annotation.Include;
 import com.yahoo.elide.annotation.ToOne;
 import com.yahoo.elide.core.EntityDictionary;
+import com.yahoo.elide.core.Path;
 import com.yahoo.elide.datastores.aggregation.annotation.Meta;
 import com.yahoo.elide.datastores.aggregation.metadata.enums.ValueType;
 
 import lombok.Data;
 import lombok.EqualsAndHashCode;
 import lombok.ToString;
 
+import java.util.Collections;
 import java.util.Date;
 import java.util.HashSet;
 import java.util.Set;
@@ -45,6 +47,11 @@ public abstract class Column {
 
     private ValueType valueType;
 
+    @ToOne
+    @ToString.Exclude
+    @EqualsAndHashCode.Exclude
+    private Column sourceColumn;
+
     @ToString.Exclude
     private Set<String> columnTags;
 
@@ -83,4 +90,17 @@ public static ValueType getValueType(Class<?> tableClass, String fieldName, Enti
             }
         }
     }
+
+    /**
+     * Return a Path that navigate to the source of this column.
+     *
+     * @param metadataDictionary metadata dictionary
+     * @return Path to source column
+     */
+    public Path getSourcePath(EntityDictionary metadataDictionary) {
+        Class<?> tableCls = metadataDictionary.getEntityClass(table.getId());
+        Class<?> columnCls = metadataDictionary.getParameterizedType(tableCls, getName());
+
+        return new Path(Collections.singletonList(new Path.PathElement(tableCls, columnCls, getName())));
+    }
 }

elide-datastore/elide-datastore-aggregation/src/main/java/com/yahoo/elide/datastores/aggregation/queryengines/sql/metadata/SQLColumn.java

@@ -6,11 +6,16 @@
 package com.yahoo.elide.datastores.aggregation.queryengines.sql.metadata;
 
 import com.yahoo.elide.datastores.aggregation.core.JoinPath;
+import com.yahoo.elide.datastores.aggregation.metadata.models.Table;
 
 /**
  * Column with physical SQL information like reference and join to path.
  */
 public interface SQLColumn {
+    Table getTable();
+
+    String getName();
+
     String getReference();
 
     JoinPath getJoinPath();

elide-datastore/elide-datastore-aggregation/src/main/java/com/yahoo/elide/datastores/aggregation/queryengines/sql/metadata/SQLDimension.java

@@ -9,6 +9,7 @@
 import static com.yahoo.elide.datastores.aggregation.queryengines.sql.SQLQueryEngine.getClassAlias;
 
 import com.yahoo.elide.core.EntityDictionary;
+import com.yahoo.elide.core.Path;
 import com.yahoo.elide.datastores.aggregation.core.JoinPath;
 import com.yahoo.elide.datastores.aggregation.metadata.models.Dimension;
 import com.yahoo.elide.datastores.aggregation.metadata.models.Table;
@@ -26,6 +27,9 @@ public class SQLDimension extends Dimension implements SQLColumn {
     @Getter
     private final JoinPath joinPath;
 
+    @Getter
+    private EntityDictionary metadataDictionary;
+
     public SQLDimension(Table table, String fieldName, EntityDictionary dictionary) {
         super(table, fieldName, dictionary);
         Class<?> tableClass = dictionary.getEntityClass(table.getId());
@@ -40,5 +44,12 @@ public SQLDimension(Table table, String fieldName, EntityDictionary dictionary)
             this.reference = generateColumnReference(path, dictionary);
             this.joinPath = path;
         }
+
+        this.metadataDictionary = dictionary;
+    }
+
+    @Override
+    public Path getSourcePath(EntityDictionary metadataDictionary) {
+        return joinPath == null ? super.getSourcePath(metadataDictionary) : joinPath;
     }
 }

elide-datastore/elide-datastore-aggregation/src/main/java/com/yahoo/elide/datastores/aggregation/queryengines/sql/metadata/SQLTimeDimension.java

@@ -9,6 +9,7 @@
 import static com.yahoo.elide.datastores.aggregation.queryengines.sql.SQLQueryEngine.getClassAlias;
 
 import com.yahoo.elide.core.EntityDictionary;
+import com.yahoo.elide.core.Path;
 import com.yahoo.elide.datastores.aggregation.core.JoinPath;
 import com.yahoo.elide.datastores.aggregation.metadata.models.Table;
 import com.yahoo.elide.datastores.aggregation.metadata.models.TimeDimension;
@@ -26,6 +27,9 @@ public class SQLTimeDimension extends TimeDimension implements SQLColumn {
     @Getter
     private final JoinPath joinPath;
 
+    @Getter
+    private EntityDictionary metadataDictionary;
+
     public SQLTimeDimension(Table table, String fieldName, EntityDictionary dictionary) {
         super(table, fieldName, dictionary);
         Class<?> tableClass = dictionary.getEntityClass(table.getId());
@@ -40,5 +44,12 @@ public SQLTimeDimension(Table table, String fieldName, EntityDictionary dictiona
             this.reference = generateColumnReference(path, dictionary);
             this.joinPath = path;
         }
+
+        this.metadataDictionary = dictionary;
+    }
+
+    @Override
+    public Path getSourcePath(EntityDictionary metadataDictionary) {
+        return joinPath == null ? super.getSourcePath(metadataDictionary) : joinPath;
     }
 }

elide-datastore/elide-datastore-aggregation/src/test/java/com/yahoo/elide/datastores/aggregation/framework/SQLUnitTest.java

@@ -39,7 +39,7 @@ public abstract class SQLUnitTest {
     protected static Table playerStatsTable;
     protected static EntityDictionary dictionary;
     protected static RSQLFilterDialect filterParser;
-    protected static MetaDataStore metaDataStore = new MetaDataStore();
+    protected static MetaDataStore metaDataStore;
 
     protected static final Country HONG_KONG = new Country();
     protected static final Country USA = new Country();
@@ -49,6 +49,8 @@ public abstract class SQLUnitTest {
     protected static QueryEngine engine;
 
     public static void init() {
+        metaDataStore = new MetaDataStore();
+
         emf = Persistence.createEntityManagerFactory("aggregationStore");
         dictionary = new EntityDictionary(new HashMap<>());
         dictionary.bindEntity(PlayerStatsWithView.class);

elide-datastore/elide-datastore-aggregation/src/test/java/com/yahoo/elide/datastores/aggregation/integration/AggregationDataStoreIntegrationTest.java

@@ -690,6 +690,7 @@ public void metaDataTest() {
                 .statusCode(HttpStatus.SC_OK)
                 .body("data.attributes.name", equalTo("playerName"))
                 .body("data.attributes.valueType",  equalTo("TEXT"))
+                .body("data.relationships.sourceColumn.data.id", equalTo("player.name"))
                 .body("data.relationships.table.data.id", equalTo("playerStats"));
 
         given()
@@ -699,6 +700,7 @@ public void metaDataTest() {
                 .statusCode(HttpStatus.SC_OK)
                 .body("data.attributes.name", equalTo("lowScore"))
                 .body("data.attributes.valueType",  equalTo("INTEGER"))
+                .body("data.relationships.sourceColumn.data.id", equalTo("playerStats.lowScore"))
                 .body("data.relationships.table.data.id", equalTo("playerStats"))
                 .body("data.relationships.metricFunction.data.id", equalTo("playerStats.lowScore[min]"))
                 .body("included.id", hasItem("playerStats.lowScore[min]"))
@@ -713,6 +715,7 @@ public void metaDataTest() {
                 .statusCode(HttpStatus.SC_OK)
                 .body("data.attributes.name", equalTo("recordedDate"))
                 .body("data.attributes.valueType",  equalTo("TIME"))
+                .body("data.relationships.sourceColumn.data.id", equalTo("playerStats.recordedDate"))
                 .body("data.relationships.table.data.id", equalTo("playerStats"))
                 .body(
                         "data.relationships.supportedGrains.data.id",