Implement Dereference pushdown for the Delta Lake connector

docs/src/main/sphinx/connector/delta-lake.rst

@@ -190,6 +190,9 @@ configure processing of Parquet files.
     * - ``parquet_writer_batch_size``
       - Maximum number of rows processed by the Parquet writer in a batch.
       - ``10000``
+    * - ``projection_pushdown_enabled``
+      - Read only projected fields from row columns while performing ``SELECT`` queries
+      - ``true``
 
 .. _delta-lake-type-mapping:
 
@@ -930,3 +933,6 @@ connector.
         for structural data types. The equivalent catalog session property is
         ``parquet_optimized_nested_reader_enabled``.
       - ``true``
+    * - ``delta.projection-pushdown-enabled``
+      - Read only projected fields from row columns while performing ``SELECT`` queries
+      - ``true``

plugin/trino-delta-lake/src/main/java/io/trino/plugin/deltalake/AbstractDeltaLakePageSink.java

@@ -155,16 +155,17 @@ public AbstractDeltaLakePageSink(
             DeltaLakeColumnHandle column = inputColumns.get(inputIndex);
             switch (column.getColumnType()) {
                 case PARTITION_KEY:
-                    int partitionPosition = canonicalToOriginalPartitionPositions.get(column.getName());
+                    int partitionPosition = canonicalToOriginalPartitionPositions.get(column.getColumnName());
                     partitionColumnInputIndex[partitionPosition] = inputIndex;
-                    originalPartitionColumnNames[partitionPosition] = canonicalToOriginalPartitionColumns.get(column.getName());
-                    partitionColumnTypes[partitionPosition] = column.getType();
+                    originalPartitionColumnNames[partitionPosition] = canonicalToOriginalPartitionColumns.get(column.getColumnName());
+                    partitionColumnTypes[partitionPosition] = column.getBaseType();
                     break;
                 case REGULAR:
+                    verify(column.isBaseColumn(), "Unexpected dereference: %s", column);
                     dataColumnHandles.add(column);
                     dataColumnsInputIndex.add(inputIndex);
-                    dataColumnNames.add(column.getPhysicalName());
-                    dataColumnTypes.add(column.getPhysicalType());
+                    dataColumnNames.add(column.getBasePhysicalColumnName());
+                    dataColumnTypes.add(column.getBasePhysicalType());
                     break;
                 case SYNTHESIZED:
                     processSynthesizedColumn(column);

plugin/trino-delta-lake/src/main/java/io/trino/plugin/deltalake/DeltaLakeBucketFunction.java

@@ -22,6 +22,7 @@
 import java.util.List;
 
 import static com.google.common.base.Throwables.throwIfUnchecked;
+import static com.google.common.base.Verify.verify;
 import static com.google.common.collect.ImmutableList.toImmutableList;
 import static io.trino.spi.function.InvocationConvention.InvocationArgumentConvention.BLOCK_POSITION;
 import static io.trino.spi.function.InvocationConvention.InvocationReturnConvention.FAIL_ON_NULL;
@@ -37,7 +38,8 @@ public class DeltaLakeBucketFunction
     public DeltaLakeBucketFunction(TypeOperators typeOperators, List<DeltaLakeColumnHandle> partitioningColumns, int bucketCount)
     {
         this.hashCodeInvokers = partitioningColumns.stream()
-                .map(DeltaLakeColumnHandle::getType)
+                .peek(column -> verify(column.isBaseColumn(), "Unexpected dereference: %s", column))
+                .map(DeltaLakeColumnHandle::getBaseType)
                 .map(type -> typeOperators.getHashCodeOperator(type, simpleConvention(FAIL_ON_NULL, BLOCK_POSITION)))
                 .collect(toImmutableList());
         this.bucketCount = bucketCount;

plugin/trino-delta-lake/src/main/java/io/trino/plugin/deltalake/DeltaLakeColumnHandle.java

@@ -14,6 +14,7 @@
 package io.trino.plugin.deltalake;
 
 import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import io.trino.plugin.hive.HiveColumnHandle;
 import io.trino.spi.connector.ColumnHandle;
@@ -23,10 +24,13 @@
 import java.util.Optional;
 import java.util.OptionalInt;
 
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.base.Preconditions.checkState;
 import static io.airlift.slice.SizeOf.estimatedSizeOf;
 import static io.airlift.slice.SizeOf.instanceSize;
 import static io.airlift.slice.SizeOf.sizeOf;
 import static io.trino.plugin.deltalake.DeltaHiveTypeTranslator.toHiveType;
+import static io.trino.plugin.deltalake.DeltaLakeColumnType.REGULAR;
 import static io.trino.plugin.deltalake.DeltaLakeColumnType.SYNTHESIZED;
 import static io.trino.spi.type.BigintType.BIGINT;
 import static io.trino.spi.type.RowType.field;
@@ -56,64 +60,68 @@ public class DeltaLakeColumnHandle
     public static final String FILE_MODIFIED_TIME_COLUMN_NAME = "$file_modified_time";
     public static final Type FILE_MODIFIED_TIME_TYPE = TIMESTAMP_TZ_MILLIS;
 
-    private final String name;
-    private final Type type;
-    private final OptionalInt fieldId;
+    private final String baseColumnName;
+    private final Type baseType;
+    private final OptionalInt baseFieldId;
     // Hold field names in Parquet files
     // The value is same as 'name' when the column mapping mode is none
     // The value is same as 'delta.columnMapping.physicalName' when the column mapping mode is id or name. e.g. col-6707cc9e-f3aa-4e6b-b8ef-1b03d3475680
-    private final String physicalName;
+    private final String basePhysicalColumnName;
     // Hold type in Parquet files
     // The value is same as 'type' when the column mapping mode is none
     // The value is same as 'delta.columnMapping.physicalName' when the column mapping mode is id or name. e.g. row(col-5924c8b3-04cf-4146-abb5-2c229e7ff708 integer)
-    private final Type physicalType;
+    private final Type basePhysicalType;
     private final DeltaLakeColumnType columnType;
+    private final Optional<DeltaLakeColumnProjectionInfo> projectionInfo;
 
     @JsonCreator
     public DeltaLakeColumnHandle(
-            @JsonProperty("name") String name,
-            @JsonProperty("type") Type type,
-            @JsonProperty("fieldId") OptionalInt fieldId,
-            @JsonProperty("physicalName") String physicalName,
-            @JsonProperty("physicalType") Type physicalType,
-            @JsonProperty("columnType") DeltaLakeColumnType columnType)
-    {
-        this.name = requireNonNull(name, "name is null");
-        this.type = requireNonNull(type, "type is null");
-        this.fieldId = requireNonNull(fieldId, "fieldId is null");
-        this.physicalName = requireNonNull(physicalName, "physicalName is null");
-        this.physicalType = requireNonNull(physicalType, "physicalType is null");
+            @JsonProperty("baseColumnName") String baseColumnName,
+            @JsonProperty("baseType") Type baseType,
+            @JsonProperty("baseFieldId") OptionalInt baseFieldId,
+            @JsonProperty("basePhysicalColumnName") String basePhysicalColumnName,
+            @JsonProperty("basePhysicalType") Type basePhysicalType,
+            @JsonProperty("columnType") DeltaLakeColumnType columnType,
+            @JsonProperty("projectionInfo") Optional<DeltaLakeColumnProjectionInfo> projectionInfo)
+    {
+        this.baseColumnName = requireNonNull(baseColumnName, "baseColumnName is null");
+        this.baseType = requireNonNull(baseType, "baseType is null");
+        this.baseFieldId = requireNonNull(baseFieldId, "baseFieldId is null");
+        this.basePhysicalColumnName = requireNonNull(basePhysicalColumnName, "basePhysicalColumnName is null");
+        this.basePhysicalType = requireNonNull(basePhysicalType, "basePhysicalType is null");
         this.columnType = requireNonNull(columnType, "columnType is null");
+        checkArgument(projectionInfo.isEmpty() || columnType == REGULAR, "Projection info present for column type: %s", columnType);
+        this.projectionInfo = projectionInfo;
     }
 
     @JsonProperty
-    public String getName()
+    public String getBaseColumnName()
     {
-        return name;
+        return baseColumnName;
     }
 
     @JsonProperty
-    public Type getType()
+    public Type getBaseType()
     {
-        return type;
+        return baseType;
     }
 
     @JsonProperty
-    public OptionalInt getFieldId()
+    public OptionalInt getBaseFieldId()
     {
-        return fieldId;
+        return baseFieldId;
     }
 
     @JsonProperty
-    public String getPhysicalName()
+    public String getBasePhysicalColumnName()
     {
-        return physicalName;
+        return basePhysicalColumnName;
     }
 
     @JsonProperty
-    public Type getPhysicalType()
+    public Type getBasePhysicalType()
     {
-        return physicalType;
+        return basePhysicalType;
     }
 
     @JsonProperty
@@ -122,6 +130,12 @@ public DeltaLakeColumnType getColumnType()
         return columnType;
     }
 
+    @JsonProperty
+    public Optional<DeltaLakeColumnProjectionInfo> getProjectionInfo()
+    {
+        return projectionInfo;
+    }
+
     @Override
     public boolean equals(Object obj)
     {
@@ -132,64 +146,88 @@ public boolean equals(Object obj)
             return false;
         }
         DeltaLakeColumnHandle other = (DeltaLakeColumnHandle) obj;
-        return Objects.equals(this.name, other.name) &&
-                Objects.equals(this.type, other.type) &&
-                Objects.equals(this.fieldId, other.fieldId) &&
-                Objects.equals(this.physicalName, other.physicalName) &&
-                Objects.equals(this.physicalType, other.physicalType) &&
-                this.columnType == other.columnType;
+        return Objects.equals(this.baseColumnName, other.baseColumnName) &&
+                Objects.equals(this.baseType, other.baseType) &&
+                Objects.equals(this.baseFieldId, other.baseFieldId) &&
+                Objects.equals(this.basePhysicalColumnName, other.basePhysicalColumnName) &&
+                Objects.equals(this.basePhysicalType, other.basePhysicalType) &&
+                this.columnType == other.columnType &&
+                Objects.equals(this.projectionInfo, other.projectionInfo);
+    }
+
+    @JsonIgnore
+    public String getColumnName()
+    {
+        checkState(isBaseColumn(), "Unexpected dereference: %s", this);
+        return baseColumnName;
+    }
+
+    @JsonIgnore
+    public String getQualifiedPhysicalName()
+    {
+        return projectionInfo.map(projectionInfo -> basePhysicalColumnName + "#" + projectionInfo.getPartialName())
+                .orElse(basePhysicalColumnName);
     }
 
     public long getRetainedSizeInBytes()
     {
         // type is not accounted for as the instances are cached (by TypeRegistry) and shared
         return INSTANCE_SIZE
-                + estimatedSizeOf(name)
-                + sizeOf(fieldId)
-                + estimatedSizeOf(physicalName);
+                + estimatedSizeOf(baseColumnName)
+                + sizeOf(baseFieldId)
+                + estimatedSizeOf(basePhysicalColumnName)
+                + projectionInfo.map(DeltaLakeColumnProjectionInfo::getRetainedSizeInBytes).orElse(0L);
+    }
+
+    @JsonIgnore
+    public boolean isBaseColumn()
+    {
+        return projectionInfo.isEmpty();
     }
 
     @Override
     public int hashCode()
     {
-        return Objects.hash(name, type, fieldId, physicalName, physicalType, columnType);
+        return Objects.hash(baseColumnName, baseType, baseFieldId, basePhysicalColumnName, basePhysicalType, columnType, projectionInfo);
     }
 
     @Override
     public String toString()
     {
-        return name + ":" + type.getDisplayName() + ":" + columnType;
+        return getQualifiedPhysicalName() +
+                ":" + projectionInfo.map(DeltaLakeColumnProjectionInfo::getType).orElse(baseType).getDisplayName() +
+                ":" + columnType;
     }
 
     public HiveColumnHandle toHiveColumnHandle()
     {
         return new HiveColumnHandle(
-                physicalName, // this name is used for accessing Parquet files, so it should be physical name
+                basePhysicalColumnName, // this name is used for accessing Parquet files, so it should be physical name
                 0, // hiveColumnIndex; we provide fake value because we always find columns by name
-                toHiveType(physicalType),
-                physicalType,
-                Optional.empty(),
+                toHiveType(basePhysicalType),
+                basePhysicalType,
+                projectionInfo.map(DeltaLakeColumnProjectionInfo::toHiveColumnProjectionInfo),
                 columnType.toHiveColumnType(),
                 Optional.empty());
     }
 
     public static DeltaLakeColumnHandle pathColumnHandle()
     {
-        return new DeltaLakeColumnHandle(PATH_COLUMN_NAME, PATH_TYPE, OptionalInt.empty(), PATH_COLUMN_NAME, PATH_TYPE, SYNTHESIZED);
+        return new DeltaLakeColumnHandle(PATH_COLUMN_NAME, PATH_TYPE, OptionalInt.empty(), PATH_COLUMN_NAME, PATH_TYPE, SYNTHESIZED, Optional.empty());
     }
 
     public static DeltaLakeColumnHandle fileSizeColumnHandle()
     {
-        return new DeltaLakeColumnHandle(FILE_SIZE_COLUMN_NAME, FILE_SIZE_TYPE, OptionalInt.empty(), FILE_SIZE_COLUMN_NAME, FILE_SIZE_TYPE, SYNTHESIZED);
+        return new DeltaLakeColumnHandle(FILE_SIZE_COLUMN_NAME, FILE_SIZE_TYPE, OptionalInt.empty(), FILE_SIZE_COLUMN_NAME, FILE_SIZE_TYPE, SYNTHESIZED, Optional.empty());
     }
 
     public static DeltaLakeColumnHandle fileModifiedTimeColumnHandle()
     {
-        return new DeltaLakeColumnHandle(FILE_MODIFIED_TIME_COLUMN_NAME, FILE_MODIFIED_TIME_TYPE, OptionalInt.empty(), FILE_MODIFIED_TIME_COLUMN_NAME, FILE_MODIFIED_TIME_TYPE, SYNTHESIZED);
+        return new DeltaLakeColumnHandle(FILE_MODIFIED_TIME_COLUMN_NAME, FILE_MODIFIED_TIME_TYPE, OptionalInt.empty(), FILE_MODIFIED_TIME_COLUMN_NAME, FILE_MODIFIED_TIME_TYPE, SYNTHESIZED, Optional.empty());
     }
 
     public static DeltaLakeColumnHandle mergeRowIdColumnHandle()
     {
-        return new DeltaLakeColumnHandle(ROW_ID_COLUMN_NAME, MERGE_ROW_ID_TYPE, OptionalInt.empty(), ROW_ID_COLUMN_NAME, MERGE_ROW_ID_TYPE, SYNTHESIZED);
+        return new DeltaLakeColumnHandle(ROW_ID_COLUMN_NAME, MERGE_ROW_ID_TYPE, OptionalInt.empty(), ROW_ID_COLUMN_NAME, MERGE_ROW_ID_TYPE, SYNTHESIZED, Optional.empty());
     }
 }