the-other-tim-brown commented on code in PR #729:
URL: https://github.com/apache/incubator-xtable/pull/729#discussion_r2565567891
##########
pom.xml:
##########
@@ -615,6 +616,20 @@
<artifactId>jettison</artifactId>
<version>1.5.4</version>
</dependency>
+ <dependency>
+ <groupId>io.delta</groupId>
+ <artifactId>delta-kernel-api</artifactId>
+ <version>${delta.kernel.version}</version>
+ <scope>provided</scope>
Review Comment:
We'll want these to be the default compile scope. I think that will make it
easier than requiring users to provide their own version at runtime.
##########
xtable-core/src/main/java/org/apache/xtable/kernel/DeltaKernelTableExtractor.java:
##########
@@ -0,0 +1,92 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.xtable.kernel;
+
+import java.time.Instant;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import lombok.Builder;
+
+import io.delta.kernel.Snapshot;
+import io.delta.kernel.Table;
+import io.delta.kernel.engine.Engine;
+import io.delta.kernel.types.StructField;
+import io.delta.kernel.types.StructType;
+
+import org.apache.xtable.exception.SchemaExtractorException;
+import org.apache.xtable.model.InternalTable;
+import org.apache.xtable.model.schema.InternalPartitionField;
+import org.apache.xtable.model.schema.InternalSchema;
+import org.apache.xtable.model.storage.DataLayoutStrategy;
+import org.apache.xtable.model.storage.TableFormat;
+
+/**
+ * Extracts {@link InternalTable} canonical representation of a table at a
point in time for Delta.
+ */
+@Builder
+public class DeltaKernelTableExtractor {
+ @Builder.Default
+ private static final DeltaKernelSchemaExtractor schemaExtractor =
+ DeltaKernelSchemaExtractor.getInstance();
+
+ private final String basePath;
+
+ public InternalTable table(
+ Table deltaKernelTable, Snapshot snapshot, Engine engine, String
tableName, String basePath) {
+ try {
+ // Get schema from Delta Kernel's snapshot
+ StructType schema = snapshot.getSchema();
+ InternalSchema internalSchema = schemaExtractor.toInternalSchema(schema);
+ // Get partition columns
+ StructType fullSchema = snapshot.getSchema(); // The full table schema
+ List<String> partitionColumns = snapshot.getPartitionColumnNames();
+ List<StructField> partitionFieldSchemas =
+ fullSchema.fields().stream()
+ .filter(field -> partitionColumns.contains(field.getName()))
+ .collect(Collectors.toList());
+ StructType partitionSchema = new StructType(partitionFieldSchemas);
+
+ List<InternalPartitionField> partitionFields =
+ DeltaKernelPartitionExtractor.getInstance()
+ .convertFromDeltaPartitionFormat(internalSchema,
partitionSchema);
+
+ DataLayoutStrategy dataLayoutStrategy =
+ !partitionFields.isEmpty()
+ ? DataLayoutStrategy.HIVE_STYLE_PARTITION
+ : DataLayoutStrategy.FLAT;
+
+ // Get the timestamp
+ long timestamp = snapshot.getTimestamp(engine);
+ return InternalTable.builder()
+ .tableFormat(TableFormat.DELTA)
+ .basePath(basePath)
+ .name(tableName)
+ .layoutStrategy(dataLayoutStrategy)
+ .partitioningFields(partitionFields)
+ .readSchema(internalSchema)
+ .latestCommitTime(Instant.ofEpochMilli(timestamp))
+ .latestMetadataPath(basePath + "/_delta_log")
+ .build();
+ } catch (Exception e) {
Review Comment:
If this is just some general catch-all, my recommendation is to remove it.
If this is supposed to catch some specific exception from the schema
extraction, let's catch that particular exception.
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