[GitHub] [hudi] bvaradar commented on a change in pull request #3808: [HUDI-2560] introduce id_based schema to support full schema evolution.

[GitBox <gi...@apache.org>]

bvaradar commented on a change in pull request #3808:
URL: https://github.com/apache/hudi/pull/3808#discussion_r827175943



##########
File path: hudi-common/src/main/java/org/apache/hudi/internal/schema/io/FileBasedInternalSchemaStorageManager.java
##########
@@ -0,0 +1,169 @@
+/*
+ * 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.hudi.internal.schema.io;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FSDataInputStream;
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Path;
+import org.apache.hudi.common.table.HoodieTableMetaClient;
+import org.apache.hudi.common.table.timeline.HoodieActiveTimeline;
+import org.apache.hudi.common.table.timeline.HoodieInstant;
+import org.apache.hudi.common.util.FileIOUtils;
+import org.apache.hudi.common.util.Option;
+import org.apache.hudi.exception.HoodieException;
+import org.apache.hudi.exception.HoodieIOException;
+import org.apache.hudi.internal.schema.InternalSchema;
+import org.apache.hudi.internal.schema.utils.SerDeHelper;
+
+import org.apache.log4j.LogManager;
+import org.apache.log4j.Logger;
+
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.util.Arrays;
+import java.util.List;
+import java.util.TreeMap;
+import java.util.stream.Collectors;
+
+import static org.apache.hudi.common.table.timeline.HoodieTimeline.SAVE_SCHEMA_ACTION;
+
+public class FileBasedInternalSchemaStorageManager extends AbstractInternalSchemaStorageManager {
+  private static final Logger LOG = LogManager.getLogger(FileBasedInternalSchemaStorageManager.class);
+
+  public static final String SCHEMA_NAME = ".schema";
+  private final Path baseSchemaPath;
+  private Configuration conf;
+  private HoodieTableMetaClient metaClient;
+
+  public FileBasedInternalSchemaStorageManager(Configuration conf, Path baseTablePath) {
+    Path metaPath = new Path(baseTablePath, ".hoodie");
+    this.baseSchemaPath = new Path(metaPath, SCHEMA_NAME);
+    this.conf = conf;
+    this.metaClient = HoodieTableMetaClient.builder().setBasePath(metaPath.getParent().toString()).setConf(conf).build();
+  }
+
+  public FileBasedInternalSchemaStorageManager(HoodieTableMetaClient metaClient) {
+    Path metaPath = new Path(metaClient.getBasePath(), ".hoodie");
+    this.baseSchemaPath = new Path(metaPath, SCHEMA_NAME);
+    this.conf = metaClient.getHadoopConf();
+    this.metaClient = metaClient;
+  }
+
+  @Override
+  public void persistHistorySchemaStr(String instantTime, String historySchemaStr) {
+    cleanResidualFiles();
+    HoodieActiveTimeline timeline = metaClient.getActiveTimeline();
+    HoodieInstant hoodieInstant = new HoodieInstant(HoodieInstant.State.REQUESTED, SAVE_SCHEMA_ACTION, instantTime);
+    timeline.createNewInstant(hoodieInstant);
+    byte[] writeContent = historySchemaStr.getBytes(StandardCharsets.UTF_8);
+    timeline.transitionRequestedToInflight(hoodieInstant, Option.empty());
+    timeline.saveAsComplete(new HoodieInstant(HoodieInstant.State.INFLIGHT, hoodieInstant.getAction(), hoodieInstant.getTimestamp()), Option.of(writeContent));
+    LOG.info(String.format("persist history schema success on commit time: %s", instantTime));
+  }
+
+  private void cleanResidualFiles() {
+    List<String> validateCommits = getValidInstants();

Review comment:
       Rename validateCommits to validInstants

##########
File path: hudi-common/src/main/java/org/apache/hudi/internal/schema/InternalSchema.java
##########
@@ -0,0 +1,281 @@
+/*
+ * 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.hudi.internal.schema;
+
+import org.apache.hudi.common.util.StringUtils;
+import org.apache.hudi.internal.schema.Types.Field;
+import org.apache.hudi.internal.schema.Types.RecordType;
+import org.apache.hudi.internal.schema.utils.InternalSchemaUtils;
+
+import java.io.Serializable;
+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+/**
+ * Internal schema for hudi table.
+ * used to support schema evolution.
+ */
+public class InternalSchema implements Serializable {
+
+  private static final long DEFAULT_VERSION_ID = 0;
+
+  private final RecordType record;
+
+  private int maxColumnId;
+  private long versionId;
+
+  private transient Map<Integer, Field> idToField = null;
+  private transient Map<String, Integer> nameToId = null;
+  private transient Map<Integer, String> idToName = null;
+
+  public InternalSchema(List<Field> columns) {
+    this(DEFAULT_VERSION_ID, columns);
+  }
+
+  public InternalSchema(Field... columns) {
+    this(DEFAULT_VERSION_ID, Arrays.asList(columns));
+  }
+
+  public InternalSchema(long versionId, List<Field> cols) {
+    this.versionId = versionId;
+    this.record = RecordType.get(cols);
+    buildIdToName();
+    maxColumnId = idToName.keySet().stream().max(Comparator.comparing(Integer::valueOf)).get();
+  }
+
+  public InternalSchema(long versionId, int maxColumnId, List<Field> cols) {
+    this.maxColumnId = maxColumnId;
+    this.versionId = versionId;
+    this.record = RecordType.get(cols);
+    buildIdToName();
+  }
+
+  public InternalSchema(long versionId, int maxColumnId, Field... cols) {
+    this(versionId, maxColumnId, Arrays.asList(cols));
+  }
+
+  public RecordType getRecord() {
+    return record;
+  }
+
+  private Map<Integer, String> buildIdToName() {
+    if (idToName == null) {
+      idToName = InternalSchemaUtils.buildIdToName(record);
+    }
+    return idToName;
+  }
+
+  private Map<String, Integer> buildNameToId() {
+    if (nameToId == null) {
+      if (idToName != null && !idToName.isEmpty()) {
+        nameToId = idToName.entrySet().stream().collect(Collectors.toMap(Map.Entry::getValue, Map.Entry::getKey));
+        return nameToId;
+      }
+      nameToId = InternalSchemaUtils.buildNameToId(record);
+    }
+    return nameToId;
+  }
+
+  private Map<Integer, Field> buildIdToField() {
+    if (idToField == null) {
+      idToField = InternalSchemaUtils.buildIdToField(record);
+    }
+    return idToField;
+  }
+
+  /**
+   * get all columns full name.
+   */
+  public List<String> getAllColsFullName() {
+    if (nameToId == null) {
+      nameToId = InternalSchemaUtils.buildNameToId(record);
+    }
+    return Arrays.asList(nameToId.keySet().toArray(new String[0]));
+  }
+
+  /**
+   * set the version ID for this schema.
+   */
+  public InternalSchema setSchemaId(long versionId) {
+    this.versionId = versionId;
+    return this;
+  }
+
+  /**
+   * Returns the version ID for this schema.
+   */
+  public long schemaId() {
+    return this.versionId;
+  }
+
+  /**
+   * set the version ID for this schema.
+   */
+  public void setMax_column_id(int maxColumnId) {

Review comment:
       Please make all the method names camelCase. 

##########
File path: hudi-common/src/main/java/org/apache/hudi/internal/schema/io/FileBasedInternalSchemaStorageManager.java
##########
@@ -0,0 +1,169 @@
+/*
+ * 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.hudi.internal.schema.io;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FSDataInputStream;
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Path;
+import org.apache.hudi.common.table.HoodieTableMetaClient;
+import org.apache.hudi.common.table.timeline.HoodieActiveTimeline;
+import org.apache.hudi.common.table.timeline.HoodieInstant;
+import org.apache.hudi.common.util.FileIOUtils;
+import org.apache.hudi.common.util.Option;
+import org.apache.hudi.exception.HoodieException;
+import org.apache.hudi.exception.HoodieIOException;
+import org.apache.hudi.internal.schema.InternalSchema;
+import org.apache.hudi.internal.schema.utils.SerDeHelper;
+
+import org.apache.log4j.LogManager;
+import org.apache.log4j.Logger;
+
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.util.Arrays;
+import java.util.List;
+import java.util.TreeMap;
+import java.util.stream.Collectors;
+
+import static org.apache.hudi.common.table.timeline.HoodieTimeline.SAVE_SCHEMA_ACTION;
+
+public class FileBasedInternalSchemaStorageManager extends AbstractInternalSchemaStorageManager {
+  private static final Logger LOG = LogManager.getLogger(FileBasedInternalSchemaStorageManager.class);
+
+  public static final String SCHEMA_NAME = ".schema";
+  private final Path baseSchemaPath;
+  private Configuration conf;
+  private HoodieTableMetaClient metaClient;
+
+  public FileBasedInternalSchemaStorageManager(Configuration conf, Path baseTablePath) {
+    Path metaPath = new Path(baseTablePath, ".hoodie");
+    this.baseSchemaPath = new Path(metaPath, SCHEMA_NAME);
+    this.conf = conf;
+    this.metaClient = HoodieTableMetaClient.builder().setBasePath(metaPath.getParent().toString()).setConf(conf).build();
+  }
+
+  public FileBasedInternalSchemaStorageManager(HoodieTableMetaClient metaClient) {
+    Path metaPath = new Path(metaClient.getBasePath(), ".hoodie");
+    this.baseSchemaPath = new Path(metaPath, SCHEMA_NAME);
+    this.conf = metaClient.getHadoopConf();
+    this.metaClient = metaClient;
+  }
+
+  @Override
+  public void persistHistorySchemaStr(String instantTime, String historySchemaStr) {
+    cleanResidualFiles();
+    HoodieActiveTimeline timeline = metaClient.getActiveTimeline();
+    HoodieInstant hoodieInstant = new HoodieInstant(HoodieInstant.State.REQUESTED, SAVE_SCHEMA_ACTION, instantTime);
+    timeline.createNewInstant(hoodieInstant);
+    byte[] writeContent = historySchemaStr.getBytes(StandardCharsets.UTF_8);
+    timeline.transitionRequestedToInflight(hoodieInstant, Option.empty());
+    timeline.saveAsComplete(new HoodieInstant(HoodieInstant.State.INFLIGHT, hoodieInstant.getAction(), hoodieInstant.getTimestamp()), Option.of(writeContent));
+    LOG.info(String.format("persist history schema success on commit time: %s", instantTime));
+  }
+
+  private void cleanResidualFiles() {
+    List<String> validateCommits = getValidInstants();
+    try {
+      FileSystem fs = baseSchemaPath.getFileSystem(conf);
+      if (fs.exists(baseSchemaPath)) {
+        List<String> candidateSchemaFiles = Arrays.stream(fs.listStatus(baseSchemaPath)).filter(f -> f.isFile())
+            .map(file -> file.getPath().getName()).collect(Collectors.toList());
+        List<String> residualSchemaFiles = candidateSchemaFiles.stream().filter(f -> !validateCommits.contains(f.split("\\.")[0])).collect(Collectors.toList());
+        // clean residual files
+        residualSchemaFiles.forEach(f -> {
+          try {
+            fs.delete(new Path(metaClient.getSchemaFolderName(), f));
+          } catch (IOException o) {
+            throw new HoodieException(o);
+          }
+        });
+      }
+    } catch (IOException e) {
+      throw new HoodieException(e);
+    }
+  }
+
+  public void cleanOldFiles(List<String> validateCommits) {
+    try {
+      FileSystem fs = baseSchemaPath.getFileSystem(conf);
+      if (fs.exists(baseSchemaPath)) {
+        List<String> candidateSchemaFiles = Arrays.stream(fs.listStatus(baseSchemaPath)).filter(f -> f.isFile())
+            .map(file -> file.getPath().getName()).collect(Collectors.toList());
+        List<String> validateSchemaFiles = candidateSchemaFiles.stream().filter(f -> validateCommits.contains(f.split("\\.")[0])).collect(Collectors.toList());

Review comment:
       nit: validateSchemaFiles => validSchemaFiles

##########
File path: hudi-common/src/main/java/org/apache/hudi/internal/schema/action/InternalSchemaMerger.java
##########
@@ -0,0 +1,151 @@
+/*
+ * 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.hudi.internal.schema.action;
+
+import org.apache.hudi.common.util.StringUtils;
+import org.apache.hudi.internal.schema.InternalSchema;
+import org.apache.hudi.internal.schema.Type;
+import org.apache.hudi.internal.schema.Types;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * auxiliary class.
+ * help to merge file schema and query schema to produce final read schema for avro/parquet file
+ */
+public class InternalSchemaMerger {
+  private final InternalSchema fileSchema;
+  private final InternalSchema querySchema;
+  // now there exist some bugs when we use spark update/merge api,

Review comment:
       Can you add some pointers to the issue  GH/Jira issue. 




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