nsivabalan commented on a change in pull request #2915:
URL: https://github.com/apache/hudi/pull/2915#discussion_r643894403



##########
File path: 
hudi-utilities/src/main/java/org/apache/hudi/utilities/sources/JdbcSource.java
##########
@@ -0,0 +1,339 @@
+/*
+ * 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.utilities.sources;
+
+import org.apache.hudi.DataSourceUtils;
+import org.apache.hudi.common.config.TypedProperties;
+import org.apache.hudi.common.util.Option;
+import org.apache.hudi.common.util.StringUtils;
+import org.apache.hudi.common.util.collection.Pair;
+import org.apache.hudi.exception.HoodieException;
+import org.apache.hudi.utilities.SqlQueryBuilder;
+import org.apache.hudi.utilities.schema.SchemaProvider;
+
+import org.apache.hadoop.fs.FSDataInputStream;
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.io.IOUtils;
+import org.apache.log4j.LogManager;
+import org.apache.log4j.Logger;
+import org.apache.spark.api.java.JavaSparkContext;
+import org.apache.spark.sql.Column;
+import org.apache.spark.sql.DataFrameReader;
+import org.apache.spark.sql.Dataset;
+import org.apache.spark.sql.Row;
+import org.apache.spark.sql.SparkSession;
+import org.apache.spark.sql.functions;
+import org.apache.spark.sql.types.DataTypes;
+import org.apache.spark.storage.StorageLevel;
+
+import java.net.URI;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * Reads data from RDBMS data sources.
+ */
+
+public class JdbcSource extends RowSource {
+
+  private static final Logger LOG = LogManager.getLogger(JdbcSource.class);
+  private static final List<String> DB_LIMIT_CLAUSE = Arrays.asList("mysql", 
"postgresql", "h2");
+  private static final String URI_JDBC_PREFIX = "jdbc:";
+
+  public JdbcSource(TypedProperties props, JavaSparkContext sparkContext, 
SparkSession sparkSession,
+                    SchemaProvider schemaProvider) {
+    super(props, sparkContext, sparkSession, schemaProvider);
+  }
+
+  /**
+   * Validates all user properties and prepares the {@link DataFrameReader} to 
read from RDBMS.
+   *
+   * @param session    The {@link SparkSession}.
+   * @param properties The JDBC connection properties and data source options.
+   * @return The {@link DataFrameReader} to read from RDBMS
+   * @throws HoodieException
+   */
+  private static DataFrameReader validatePropsAndGetDataFrameReader(final 
SparkSession session,
+                                                                    final 
TypedProperties properties)
+      throws HoodieException {
+    DataFrameReader dataFrameReader;
+    FSDataInputStream passwordFileStream = null;
+    try {
+      dataFrameReader = session.read().format("jdbc");
+      dataFrameReader = dataFrameReader.option(Config.URL_PROP, 
properties.getString(Config.URL));
+      dataFrameReader = dataFrameReader.option(Config.USER_PROP, 
properties.getString(Config.USER));
+      dataFrameReader = dataFrameReader.option(Config.DRIVER_PROP, 
properties.getString(Config.DRIVER_CLASS));
+      dataFrameReader = dataFrameReader
+          .option(Config.RDBMS_TABLE_PROP, 
properties.getString(Config.RDBMS_TABLE_NAME));
+
+      if (properties.containsKey(Config.PASSWORD)) {
+        LOG.info("Reading JDBC password from properties file....");
+        dataFrameReader = dataFrameReader.option(Config.PASSWORD_PROP, 
properties.getString(Config.PASSWORD));
+      } else if (properties.containsKey(Config.PASSWORD_FILE)
+          && 
!StringUtils.isNullOrEmpty(properties.getString(Config.PASSWORD_FILE))) {
+        LOG.info(String.format("Reading JDBC password from password file %s", 
properties.getString(Config.PASSWORD_FILE)));
+        FileSystem fileSystem = 
FileSystem.get(session.sparkContext().hadoopConfiguration());
+        passwordFileStream = fileSystem.open(new 
Path(properties.getString(Config.PASSWORD_FILE)));
+        byte[] bytes = new byte[passwordFileStream.available()];
+        passwordFileStream.read(bytes);
+        dataFrameReader = dataFrameReader.option(Config.PASSWORD_PROP, new 
String(bytes));
+      } else {
+        throw new IllegalArgumentException(String.format("JDBCSource needs 
either a %s or %s to connect to RDBMS "
+            + "datasource", Config.PASSWORD_FILE, Config.PASSWORD));
+      }
+
+      addExtraJdbcOptions(properties, dataFrameReader);
+
+      if (properties.getBoolean(Config.IS_INCREMENTAL)) {
+        DataSourceUtils.checkRequiredProperties(properties, 
Collections.singletonList(Config.INCREMENTAL_COLUMN));
+      }
+      return dataFrameReader;
+    } catch (Exception e) {
+      throw new HoodieException(e);
+    } finally {
+      IOUtils.closeStream(passwordFileStream);
+    }
+  }
+
+  /**
+   * Accepts spark JDBC options from the user in terms of EXTRA_OPTIONS adds 
them to {@link DataFrameReader} Example: In
+   * a normal spark code you would do something like: 
session.read.format('jdbc') .option(fetchSize,1000)
+   * .option(timestampFormat,"yyyy-mm-dd hh:mm:ss")
+   * <p>
+   * The way to pass these properties to HUDI is through the config file. Any 
property starting with
+   * hoodie.deltastreamer.jdbc.extra.options. will be added.
+   * <p>
+   * Example: hoodie.deltastreamer.jdbc.extra.options.fetchSize=100
+   * hoodie.deltastreamer.jdbc.extra.options.upperBound=1
+   * hoodie.deltastreamer.jdbc.extra.options.lowerBound=100
+   *
+   * @param properties      The JDBC connection properties and data source 
options.
+   * @param dataFrameReader The {@link DataFrameReader} to which data source 
options will be added.
+   */
+  private static void addExtraJdbcOptions(TypedProperties properties, 
DataFrameReader dataFrameReader) {
+    Set<Object> objects = properties.keySet();
+    for (Object property : objects) {
+      String prop = property.toString();
+      if (prop.startsWith(Config.EXTRA_OPTIONS)) {
+        String key = String.join("", prop.split(Config.EXTRA_OPTIONS));
+        String value = properties.getString(prop);
+        if (!StringUtils.isNullOrEmpty(value)) {
+          LOG.info(String.format("Adding %s -> %s to jdbc options", key, 
value));
+          dataFrameReader.option(key, value);
+        }
+      }
+    }
+  }
+
+  @Override
+  protected Pair<Option<Dataset<Row>>, String> fetchNextBatch(Option<String> 
lastCkptStr, long sourceLimit) throws HoodieException {
+    try {
+      DataSourceUtils.checkRequiredProperties(props, Arrays.asList(Config.URL, 
Config.DRIVER_CLASS, Config.USER, Config.RDBMS_TABLE_NAME, 
Config.IS_INCREMENTAL));
+      return fetch(lastCkptStr, sourceLimit);
+    } catch (Exception e) {
+      LOG.error("Exception while running JDBCSource ", e);
+      throw new HoodieException(e);
+    }
+  }
+
+  /**
+   * Decide to do a full RDBMS table scan or an incremental scan based on the 
lastCkptStr. If previous checkpoint
+   * value exists then we do an incremental scan with a PPD query or else we 
do a full scan. In certain cases where the
+   * incremental query fails, we fallback to a full scan.
+   *
+   * @param lastCkptStr Last checkpoint.
+   * @return The pair of {@link Dataset} and current checkpoint.
+   */
+  private Pair<Option<Dataset<Row>>, String> fetch(Option<String> lastCkptStr, 
long sourceLimit) {
+    Dataset<Row> dataset;
+    if (lastCkptStr.isPresent() && 
!StringUtils.isNullOrEmpty(lastCkptStr.get())) {
+      dataset = incrementalFetch(lastCkptStr, sourceLimit);
+    } else {
+      LOG.info("No checkpoint references found. Doing a full rdbms table 
fetch");
+      dataset = fullFetch(sourceLimit);
+    }
+    
dataset.persist(StorageLevel.fromString(props.getString(Config.STORAGE_LEVEL, 
"MEMORY_AND_DISK_SER")));
+    boolean isIncremental = props.getBoolean(Config.IS_INCREMENTAL);
+    Pair<Option<Dataset<Row>>, String> pair = Pair.of(Option.of(dataset), 
checkpoint(dataset, isIncremental, lastCkptStr));
+    dataset.unpersist();
+    return pair;
+  }
+
+  /**
+   * Does an incremental scan with PPQ query prepared on the bases of previous 
checkpoint.
+   *
+   * @param lastCheckpoint Last checkpoint.
+   *                       Note that the records fetched will be exclusive of 
the last checkpoint (i.e. incremental column value > lastCheckpoint).
+   * @return The {@link Dataset} after incremental fetch from RDBMS.
+   */
+  private Dataset<Row> incrementalFetch(Option<String> lastCheckpoint, long 
sourceLimit) {
+    try {
+      final String ppdQuery = "(%s) rdbms_table";
+      final SqlQueryBuilder queryBuilder = SqlQueryBuilder.select("*")
+          .from(props.getString(Config.RDBMS_TABLE_NAME))
+          .where(String.format(" %s > '%s'", 
props.getString(Config.INCREMENTAL_COLUMN), lastCheckpoint.get()));
+
+      if (sourceLimit > 0) {
+        URI jdbcURI = 
URI.create(props.getString(Config.URL).substring(URI_JDBC_PREFIX.length()));
+        if (DB_LIMIT_CLAUSE.contains(jdbcURI.getScheme())) {
+          
queryBuilder.orderBy(props.getString(Config.INCREMENTAL_COLUMN)).limit(sourceLimit);
+        }
+      }
+      String query = String.format(ppdQuery, queryBuilder.toString());
+      LOG.info("PPD QUERY: " + query);
+      LOG.info(String.format("Referenced last checkpoint and prepared new 
predicate pushdown query for jdbc pull %s", query));
+      return validatePropsAndGetDataFrameReader(sparkSession, 
props).option(Config.RDBMS_TABLE_PROP, query).load();
+    } catch (Exception e) {
+      LOG.error("Error while performing an incremental fetch. Not all database 
support the PPD query we generate to do an incremental scan", e);
+      if (props.containsKey(Config.FALLBACK_TO_FULL_FETCH) && 
props.getBoolean(Config.FALLBACK_TO_FULL_FETCH)) {
+        LOG.warn("Falling back to full scan.");
+        return fullFetch(sourceLimit);
+      }
+      throw e;
+    }
+  }
+
+  /**
+   * Does a full scan on the RDBMS data source.
+   *
+   * @return The {@link Dataset} after running full scan.
+   */
+  private Dataset<Row> fullFetch(long sourceLimit) {
+    final String ppdQuery = "(%s) rdbms_table";
+    final SqlQueryBuilder queryBuilder = SqlQueryBuilder.select("*")
+        .from(props.getString(Config.RDBMS_TABLE_NAME));
+    if (sourceLimit > 0) {
+      URI jdbcURI = 
URI.create(props.getString(Config.URL).substring(URI_JDBC_PREFIX.length()));
+      if (DB_LIMIT_CLAUSE.contains(jdbcURI.getScheme())) {
+        if (props.containsKey(Config.INCREMENTAL_COLUMN)) {
+          
queryBuilder.orderBy(props.getString(Config.INCREMENTAL_COLUMN)).limit(sourceLimit);
+        } else {
+          queryBuilder.limit(sourceLimit);
+        }
+      }
+    }
+    String query = String.format(ppdQuery, queryBuilder.toString());
+    return validatePropsAndGetDataFrameReader(sparkSession, 
props).option(Config.RDBMS_TABLE_PROP, query).load();
+  }
+
+  private String checkpoint(Dataset<Row> rowDataset, boolean isIncremental, 
Option<String> lastCkptStr) {
+    try {
+      if (isIncremental) {
+        Column incrementalColumn = 
rowDataset.col(props.getString(Config.INCREMENTAL_COLUMN));
+        final String max = 
rowDataset.agg(functions.max(incrementalColumn).cast(DataTypes.StringType)).first().getString(0);
+        LOG.info(String.format("Checkpointing column %s with value: %s ", 
incrementalColumn, max));
+        if (max != null) {
+          return max;
+        }
+        return lastCkptStr.isPresent() && 
!StringUtils.isNullOrEmpty(lastCkptStr.get()) ? lastCkptStr.get() : 
StringUtils.EMPTY_STRING;
+      } else {
+        return StringUtils.EMPTY_STRING;
+      }
+    } catch (Exception e) {
+      return StringUtils.EMPTY_STRING;
+    }
+  }
+
+  /**
+   * Inner class with config keys.
+   */
+  protected static class Config {
+
+    /**
+     * {@value #URL} is the jdbc url for the Hoodie datasource.
+     */
+    private static final String URL = "hoodie.deltastreamer.jdbc.url";
+
+    private static final String URL_PROP = "url";
+
+    /**
+     * {@value #USER} is the username used for JDBC connection.
+     */
+    private static final String USER = "hoodie.deltastreamer.jdbc.user";
+
+    /**
+     * {@value #USER_PROP} used internally to build jdbc params.
+     */
+    private static final String USER_PROP = "user";
+
+    /**
+     * {@value #PASSWORD} is the password used for JDBC connection.
+     */
+    private static final String PASSWORD = 
"hoodie.deltastreamer.jdbc.password";
+
+    /**
+     * {@value #PASSWORD_FILE} is the base-path for the JDBC password file.
+     */
+    private static final String PASSWORD_FILE = 
"hoodie.deltastreamer.jdbc.password.file";
+
+    /**
+     * {@value #PASSWORD_PROP} used internally to build jdbc params.
+     */
+    private static final String PASSWORD_PROP = "password";
+
+    /**
+     * {@value #DRIVER_CLASS} used for JDBC connection.
+     */
+    private static final String DRIVER_CLASS = 
"hoodie.deltastreamer.jdbc.driver.class";
+
+    /**
+     * {@value #DRIVER_PROP} used internally to build jdbc params.
+     */
+    private static final String DRIVER_PROP = "driver";
+
+    /**
+     * {@value #RDBMS_TABLE_NAME} RDBMS table to pull.
+     */
+    private static final String RDBMS_TABLE_NAME = 
"hoodie.deltastreamer.jdbc.table.name";
+
+    /**
+     * {@value #RDBMS_TABLE_PROP} used internally for jdbc.
+     */
+    private static final String RDBMS_TABLE_PROP = "dbtable";
+
+    /**
+     * {@value #INCREMENTAL_COLUMN} if ran in incremental mode, this field 
will be used to pull new data incrementally.
+     */
+    private static final String INCREMENTAL_COLUMN = 
"hoodie.deltastreamer.jdbc.table.incremental.column.name";
+
+    /**
+     * {@value #IS_INCREMENTAL} will the JDBC source do an incremental pull?
+     */
+    private static final String IS_INCREMENTAL = 
"hoodie.deltastreamer.jdbc.incremental.pull";
+
+    /**
+     * {@value #EXTRA_OPTIONS} used to set any extra options the user 
specifies for jdbc.
+     */
+    private static final String EXTRA_OPTIONS = 
"hoodie.deltastreamer.jdbc.extra.options.";
+
+    /**
+     * {@value #STORAGE_LEVEL} is used to control the persistence level. 
Default value: MEMORY_AND_DISK_SER.
+     */
+    private static final String STORAGE_LEVEL = 
"hoodie.deltastreamer.jdbc.storage.level";
+
+    /**
+     * {@value #FALLBACK_TO_FULL_FETCH} is a boolean, which if set true, makes 
incremental fetch to fallback to full fetch in case of any error.
+     */
+    private static final String FALLBACK_TO_FULL_FETCH = 
"hoodie.deltastreamer.jdbc.incremental.fallback_to_full";

Review comment:
       if you consider my other comment "incr", then you could change this 
config to "hoodie.deltastreamer.jdbc.incr.fallback.to.full.fetch".
   1. incremental -> incr 
   2. replace "_" with "."
   3. suffix "fetch". 
   
   I mean, only (1) is debatable. but do fix other two. 

##########
File path: 
hudi-utilities/src/main/java/org/apache/hudi/utilities/sources/JdbcSource.java
##########
@@ -0,0 +1,339 @@
+/*
+ * 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.utilities.sources;
+
+import org.apache.hudi.DataSourceUtils;
+import org.apache.hudi.common.config.TypedProperties;
+import org.apache.hudi.common.util.Option;
+import org.apache.hudi.common.util.StringUtils;
+import org.apache.hudi.common.util.collection.Pair;
+import org.apache.hudi.exception.HoodieException;
+import org.apache.hudi.utilities.SqlQueryBuilder;
+import org.apache.hudi.utilities.schema.SchemaProvider;
+
+import org.apache.hadoop.fs.FSDataInputStream;
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.io.IOUtils;
+import org.apache.log4j.LogManager;
+import org.apache.log4j.Logger;
+import org.apache.spark.api.java.JavaSparkContext;
+import org.apache.spark.sql.Column;
+import org.apache.spark.sql.DataFrameReader;
+import org.apache.spark.sql.Dataset;
+import org.apache.spark.sql.Row;
+import org.apache.spark.sql.SparkSession;
+import org.apache.spark.sql.functions;
+import org.apache.spark.sql.types.DataTypes;
+import org.apache.spark.storage.StorageLevel;
+
+import java.net.URI;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * Reads data from RDBMS data sources.
+ */
+
+public class JdbcSource extends RowSource {
+
+  private static final Logger LOG = LogManager.getLogger(JdbcSource.class);
+  private static final List<String> DB_LIMIT_CLAUSE = Arrays.asList("mysql", 
"postgresql", "h2");
+  private static final String URI_JDBC_PREFIX = "jdbc:";
+
+  public JdbcSource(TypedProperties props, JavaSparkContext sparkContext, 
SparkSession sparkSession,
+                    SchemaProvider schemaProvider) {
+    super(props, sparkContext, sparkSession, schemaProvider);
+  }
+
+  /**
+   * Validates all user properties and prepares the {@link DataFrameReader} to 
read from RDBMS.
+   *
+   * @param session    The {@link SparkSession}.
+   * @param properties The JDBC connection properties and data source options.
+   * @return The {@link DataFrameReader} to read from RDBMS
+   * @throws HoodieException
+   */
+  private static DataFrameReader validatePropsAndGetDataFrameReader(final 
SparkSession session,
+                                                                    final 
TypedProperties properties)
+      throws HoodieException {
+    DataFrameReader dataFrameReader;
+    FSDataInputStream passwordFileStream = null;
+    try {
+      dataFrameReader = session.read().format("jdbc");
+      dataFrameReader = dataFrameReader.option(Config.URL_PROP, 
properties.getString(Config.URL));
+      dataFrameReader = dataFrameReader.option(Config.USER_PROP, 
properties.getString(Config.USER));
+      dataFrameReader = dataFrameReader.option(Config.DRIVER_PROP, 
properties.getString(Config.DRIVER_CLASS));
+      dataFrameReader = dataFrameReader
+          .option(Config.RDBMS_TABLE_PROP, 
properties.getString(Config.RDBMS_TABLE_NAME));
+
+      if (properties.containsKey(Config.PASSWORD)) {
+        LOG.info("Reading JDBC password from properties file....");
+        dataFrameReader = dataFrameReader.option(Config.PASSWORD_PROP, 
properties.getString(Config.PASSWORD));
+      } else if (properties.containsKey(Config.PASSWORD_FILE)
+          && 
!StringUtils.isNullOrEmpty(properties.getString(Config.PASSWORD_FILE))) {
+        LOG.info(String.format("Reading JDBC password from password file %s", 
properties.getString(Config.PASSWORD_FILE)));
+        FileSystem fileSystem = 
FileSystem.get(session.sparkContext().hadoopConfiguration());
+        passwordFileStream = fileSystem.open(new 
Path(properties.getString(Config.PASSWORD_FILE)));
+        byte[] bytes = new byte[passwordFileStream.available()];
+        passwordFileStream.read(bytes);
+        dataFrameReader = dataFrameReader.option(Config.PASSWORD_PROP, new 
String(bytes));
+      } else {
+        throw new IllegalArgumentException(String.format("JDBCSource needs 
either a %s or %s to connect to RDBMS "
+            + "datasource", Config.PASSWORD_FILE, Config.PASSWORD));
+      }
+
+      addExtraJdbcOptions(properties, dataFrameReader);
+
+      if (properties.getBoolean(Config.IS_INCREMENTAL)) {
+        DataSourceUtils.checkRequiredProperties(properties, 
Collections.singletonList(Config.INCREMENTAL_COLUMN));
+      }
+      return dataFrameReader;
+    } catch (Exception e) {
+      throw new HoodieException(e);
+    } finally {
+      IOUtils.closeStream(passwordFileStream);
+    }
+  }
+
+  /**
+   * Accepts spark JDBC options from the user in terms of EXTRA_OPTIONS adds 
them to {@link DataFrameReader} Example: In
+   * a normal spark code you would do something like: 
session.read.format('jdbc') .option(fetchSize,1000)
+   * .option(timestampFormat,"yyyy-mm-dd hh:mm:ss")
+   * <p>
+   * The way to pass these properties to HUDI is through the config file. Any 
property starting with
+   * hoodie.deltastreamer.jdbc.extra.options. will be added.
+   * <p>
+   * Example: hoodie.deltastreamer.jdbc.extra.options.fetchSize=100
+   * hoodie.deltastreamer.jdbc.extra.options.upperBound=1
+   * hoodie.deltastreamer.jdbc.extra.options.lowerBound=100
+   *
+   * @param properties      The JDBC connection properties and data source 
options.
+   * @param dataFrameReader The {@link DataFrameReader} to which data source 
options will be added.
+   */
+  private static void addExtraJdbcOptions(TypedProperties properties, 
DataFrameReader dataFrameReader) {
+    Set<Object> objects = properties.keySet();
+    for (Object property : objects) {
+      String prop = property.toString();
+      if (prop.startsWith(Config.EXTRA_OPTIONS)) {
+        String key = String.join("", prop.split(Config.EXTRA_OPTIONS));
+        String value = properties.getString(prop);
+        if (!StringUtils.isNullOrEmpty(value)) {
+          LOG.info(String.format("Adding %s -> %s to jdbc options", key, 
value));
+          dataFrameReader.option(key, value);
+        }
+      }
+    }
+  }
+
+  @Override
+  protected Pair<Option<Dataset<Row>>, String> fetchNextBatch(Option<String> 
lastCkptStr, long sourceLimit) throws HoodieException {
+    try {
+      DataSourceUtils.checkRequiredProperties(props, Arrays.asList(Config.URL, 
Config.DRIVER_CLASS, Config.USER, Config.RDBMS_TABLE_NAME, 
Config.IS_INCREMENTAL));
+      return fetch(lastCkptStr, sourceLimit);
+    } catch (Exception e) {
+      LOG.error("Exception while running JDBCSource ", e);
+      throw new HoodieException(e);
+    }
+  }
+
+  /**
+   * Decide to do a full RDBMS table scan or an incremental scan based on the 
lastCkptStr. If previous checkpoint
+   * value exists then we do an incremental scan with a PPD query or else we 
do a full scan. In certain cases where the
+   * incremental query fails, we fallback to a full scan.
+   *
+   * @param lastCkptStr Last checkpoint.
+   * @return The pair of {@link Dataset} and current checkpoint.
+   */
+  private Pair<Option<Dataset<Row>>, String> fetch(Option<String> lastCkptStr, 
long sourceLimit) {
+    Dataset<Row> dataset;
+    if (lastCkptStr.isPresent() && 
!StringUtils.isNullOrEmpty(lastCkptStr.get())) {
+      dataset = incrementalFetch(lastCkptStr, sourceLimit);
+    } else {
+      LOG.info("No checkpoint references found. Doing a full rdbms table 
fetch");
+      dataset = fullFetch(sourceLimit);
+    }
+    
dataset.persist(StorageLevel.fromString(props.getString(Config.STORAGE_LEVEL, 
"MEMORY_AND_DISK_SER")));
+    boolean isIncremental = props.getBoolean(Config.IS_INCREMENTAL);
+    Pair<Option<Dataset<Row>>, String> pair = Pair.of(Option.of(dataset), 
checkpoint(dataset, isIncremental, lastCkptStr));
+    dataset.unpersist();
+    return pair;
+  }
+
+  /**
+   * Does an incremental scan with PPQ query prepared on the bases of previous 
checkpoint.
+   *
+   * @param lastCheckpoint Last checkpoint.
+   *                       Note that the records fetched will be exclusive of 
the last checkpoint (i.e. incremental column value > lastCheckpoint).
+   * @return The {@link Dataset} after incremental fetch from RDBMS.
+   */
+  private Dataset<Row> incrementalFetch(Option<String> lastCheckpoint, long 
sourceLimit) {
+    try {
+      final String ppdQuery = "(%s) rdbms_table";
+      final SqlQueryBuilder queryBuilder = SqlQueryBuilder.select("*")
+          .from(props.getString(Config.RDBMS_TABLE_NAME))
+          .where(String.format(" %s > '%s'", 
props.getString(Config.INCREMENTAL_COLUMN), lastCheckpoint.get()));
+
+      if (sourceLimit > 0) {
+        URI jdbcURI = 
URI.create(props.getString(Config.URL).substring(URI_JDBC_PREFIX.length()));
+        if (DB_LIMIT_CLAUSE.contains(jdbcURI.getScheme())) {
+          
queryBuilder.orderBy(props.getString(Config.INCREMENTAL_COLUMN)).limit(sourceLimit);
+        }
+      }
+      String query = String.format(ppdQuery, queryBuilder.toString());
+      LOG.info("PPD QUERY: " + query);
+      LOG.info(String.format("Referenced last checkpoint and prepared new 
predicate pushdown query for jdbc pull %s", query));
+      return validatePropsAndGetDataFrameReader(sparkSession, 
props).option(Config.RDBMS_TABLE_PROP, query).load();
+    } catch (Exception e) {
+      LOG.error("Error while performing an incremental fetch. Not all database 
support the PPD query we generate to do an incremental scan", e);
+      if (props.containsKey(Config.FALLBACK_TO_FULL_FETCH) && 
props.getBoolean(Config.FALLBACK_TO_FULL_FETCH)) {
+        LOG.warn("Falling back to full scan.");
+        return fullFetch(sourceLimit);
+      }
+      throw e;
+    }
+  }
+
+  /**
+   * Does a full scan on the RDBMS data source.
+   *
+   * @return The {@link Dataset} after running full scan.
+   */
+  private Dataset<Row> fullFetch(long sourceLimit) {
+    final String ppdQuery = "(%s) rdbms_table";
+    final SqlQueryBuilder queryBuilder = SqlQueryBuilder.select("*")
+        .from(props.getString(Config.RDBMS_TABLE_NAME));
+    if (sourceLimit > 0) {
+      URI jdbcURI = 
URI.create(props.getString(Config.URL).substring(URI_JDBC_PREFIX.length()));
+      if (DB_LIMIT_CLAUSE.contains(jdbcURI.getScheme())) {
+        if (props.containsKey(Config.INCREMENTAL_COLUMN)) {
+          
queryBuilder.orderBy(props.getString(Config.INCREMENTAL_COLUMN)).limit(sourceLimit);
+        } else {
+          queryBuilder.limit(sourceLimit);
+        }
+      }
+    }
+    String query = String.format(ppdQuery, queryBuilder.toString());
+    return validatePropsAndGetDataFrameReader(sparkSession, 
props).option(Config.RDBMS_TABLE_PROP, query).load();
+  }
+
+  private String checkpoint(Dataset<Row> rowDataset, boolean isIncremental, 
Option<String> lastCkptStr) {
+    try {
+      if (isIncremental) {
+        Column incrementalColumn = 
rowDataset.col(props.getString(Config.INCREMENTAL_COLUMN));
+        final String max = 
rowDataset.agg(functions.max(incrementalColumn).cast(DataTypes.StringType)).first().getString(0);
+        LOG.info(String.format("Checkpointing column %s with value: %s ", 
incrementalColumn, max));
+        if (max != null) {
+          return max;
+        }
+        return lastCkptStr.isPresent() && 
!StringUtils.isNullOrEmpty(lastCkptStr.get()) ? lastCkptStr.get() : 
StringUtils.EMPTY_STRING;
+      } else {
+        return StringUtils.EMPTY_STRING;
+      }
+    } catch (Exception e) {
+      return StringUtils.EMPTY_STRING;
+    }
+  }
+
+  /**
+   * Inner class with config keys.
+   */
+  protected static class Config {
+
+    /**
+     * {@value #URL} is the jdbc url for the Hoodie datasource.
+     */
+    private static final String URL = "hoodie.deltastreamer.jdbc.url";
+
+    private static final String URL_PROP = "url";
+
+    /**
+     * {@value #USER} is the username used for JDBC connection.
+     */
+    private static final String USER = "hoodie.deltastreamer.jdbc.user";
+
+    /**
+     * {@value #USER_PROP} used internally to build jdbc params.
+     */
+    private static final String USER_PROP = "user";
+
+    /**
+     * {@value #PASSWORD} is the password used for JDBC connection.
+     */
+    private static final String PASSWORD = 
"hoodie.deltastreamer.jdbc.password";
+
+    /**
+     * {@value #PASSWORD_FILE} is the base-path for the JDBC password file.
+     */
+    private static final String PASSWORD_FILE = 
"hoodie.deltastreamer.jdbc.password.file";
+
+    /**
+     * {@value #PASSWORD_PROP} used internally to build jdbc params.
+     */
+    private static final String PASSWORD_PROP = "password";
+
+    /**
+     * {@value #DRIVER_CLASS} used for JDBC connection.
+     */
+    private static final String DRIVER_CLASS = 
"hoodie.deltastreamer.jdbc.driver.class";
+
+    /**
+     * {@value #DRIVER_PROP} used internally to build jdbc params.
+     */
+    private static final String DRIVER_PROP = "driver";
+
+    /**
+     * {@value #RDBMS_TABLE_NAME} RDBMS table to pull.
+     */
+    private static final String RDBMS_TABLE_NAME = 
"hoodie.deltastreamer.jdbc.table.name";
+
+    /**
+     * {@value #RDBMS_TABLE_PROP} used internally for jdbc.
+     */
+    private static final String RDBMS_TABLE_PROP = "dbtable";
+
+    /**
+     * {@value #INCREMENTAL_COLUMN} if ran in incremental mode, this field 
will be used to pull new data incrementally.
+     */
+    private static final String INCREMENTAL_COLUMN = 
"hoodie.deltastreamer.jdbc.table.incremental.column.name";

Review comment:
       for brevity purposes, can we do "incr" instead of "incremental". 

##########
File path: 
hudi-utilities/src/main/java/org/apache/hudi/utilities/sources/JdbcSource.java
##########
@@ -0,0 +1,339 @@
+/*
+ * 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.utilities.sources;
+
+import org.apache.hudi.DataSourceUtils;
+import org.apache.hudi.common.config.TypedProperties;
+import org.apache.hudi.common.util.Option;
+import org.apache.hudi.common.util.StringUtils;
+import org.apache.hudi.common.util.collection.Pair;
+import org.apache.hudi.exception.HoodieException;
+import org.apache.hudi.utilities.SqlQueryBuilder;
+import org.apache.hudi.utilities.schema.SchemaProvider;
+
+import org.apache.hadoop.fs.FSDataInputStream;
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.io.IOUtils;
+import org.apache.log4j.LogManager;
+import org.apache.log4j.Logger;
+import org.apache.spark.api.java.JavaSparkContext;
+import org.apache.spark.sql.Column;
+import org.apache.spark.sql.DataFrameReader;
+import org.apache.spark.sql.Dataset;
+import org.apache.spark.sql.Row;
+import org.apache.spark.sql.SparkSession;
+import org.apache.spark.sql.functions;
+import org.apache.spark.sql.types.DataTypes;
+import org.apache.spark.storage.StorageLevel;
+
+import java.net.URI;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * Reads data from RDBMS data sources.
+ */
+
+public class JdbcSource extends RowSource {
+
+  private static final Logger LOG = LogManager.getLogger(JdbcSource.class);
+  private static final List<String> DB_LIMIT_CLAUSE = Arrays.asList("mysql", 
"postgresql", "h2");
+  private static final String URI_JDBC_PREFIX = "jdbc:";
+
+  public JdbcSource(TypedProperties props, JavaSparkContext sparkContext, 
SparkSession sparkSession,
+                    SchemaProvider schemaProvider) {
+    super(props, sparkContext, sparkSession, schemaProvider);
+  }
+
+  /**
+   * Validates all user properties and prepares the {@link DataFrameReader} to 
read from RDBMS.
+   *
+   * @param session    The {@link SparkSession}.
+   * @param properties The JDBC connection properties and data source options.
+   * @return The {@link DataFrameReader} to read from RDBMS
+   * @throws HoodieException
+   */
+  private static DataFrameReader validatePropsAndGetDataFrameReader(final 
SparkSession session,
+                                                                    final 
TypedProperties properties)
+      throws HoodieException {
+    DataFrameReader dataFrameReader;
+    FSDataInputStream passwordFileStream = null;
+    try {
+      dataFrameReader = session.read().format("jdbc");
+      dataFrameReader = dataFrameReader.option(Config.URL_PROP, 
properties.getString(Config.URL));
+      dataFrameReader = dataFrameReader.option(Config.USER_PROP, 
properties.getString(Config.USER));
+      dataFrameReader = dataFrameReader.option(Config.DRIVER_PROP, 
properties.getString(Config.DRIVER_CLASS));
+      dataFrameReader = dataFrameReader
+          .option(Config.RDBMS_TABLE_PROP, 
properties.getString(Config.RDBMS_TABLE_NAME));
+
+      if (properties.containsKey(Config.PASSWORD)) {
+        LOG.info("Reading JDBC password from properties file....");
+        dataFrameReader = dataFrameReader.option(Config.PASSWORD_PROP, 
properties.getString(Config.PASSWORD));
+      } else if (properties.containsKey(Config.PASSWORD_FILE)
+          && 
!StringUtils.isNullOrEmpty(properties.getString(Config.PASSWORD_FILE))) {
+        LOG.info(String.format("Reading JDBC password from password file %s", 
properties.getString(Config.PASSWORD_FILE)));
+        FileSystem fileSystem = 
FileSystem.get(session.sparkContext().hadoopConfiguration());
+        passwordFileStream = fileSystem.open(new 
Path(properties.getString(Config.PASSWORD_FILE)));
+        byte[] bytes = new byte[passwordFileStream.available()];
+        passwordFileStream.read(bytes);
+        dataFrameReader = dataFrameReader.option(Config.PASSWORD_PROP, new 
String(bytes));
+      } else {
+        throw new IllegalArgumentException(String.format("JDBCSource needs 
either a %s or %s to connect to RDBMS "
+            + "datasource", Config.PASSWORD_FILE, Config.PASSWORD));
+      }
+
+      addExtraJdbcOptions(properties, dataFrameReader);
+
+      if (properties.getBoolean(Config.IS_INCREMENTAL)) {
+        DataSourceUtils.checkRequiredProperties(properties, 
Collections.singletonList(Config.INCREMENTAL_COLUMN));
+      }
+      return dataFrameReader;
+    } catch (Exception e) {
+      throw new HoodieException(e);
+    } finally {
+      IOUtils.closeStream(passwordFileStream);
+    }
+  }
+
+  /**
+   * Accepts spark JDBC options from the user in terms of EXTRA_OPTIONS adds 
them to {@link DataFrameReader} Example: In
+   * a normal spark code you would do something like: 
session.read.format('jdbc') .option(fetchSize,1000)
+   * .option(timestampFormat,"yyyy-mm-dd hh:mm:ss")
+   * <p>
+   * The way to pass these properties to HUDI is through the config file. Any 
property starting with
+   * hoodie.deltastreamer.jdbc.extra.options. will be added.
+   * <p>
+   * Example: hoodie.deltastreamer.jdbc.extra.options.fetchSize=100
+   * hoodie.deltastreamer.jdbc.extra.options.upperBound=1
+   * hoodie.deltastreamer.jdbc.extra.options.lowerBound=100
+   *
+   * @param properties      The JDBC connection properties and data source 
options.
+   * @param dataFrameReader The {@link DataFrameReader} to which data source 
options will be added.
+   */
+  private static void addExtraJdbcOptions(TypedProperties properties, 
DataFrameReader dataFrameReader) {
+    Set<Object> objects = properties.keySet();
+    for (Object property : objects) {
+      String prop = property.toString();
+      if (prop.startsWith(Config.EXTRA_OPTIONS)) {
+        String key = String.join("", prop.split(Config.EXTRA_OPTIONS));
+        String value = properties.getString(prop);
+        if (!StringUtils.isNullOrEmpty(value)) {
+          LOG.info(String.format("Adding %s -> %s to jdbc options", key, 
value));
+          dataFrameReader.option(key, value);
+        }
+      }
+    }
+  }
+
+  @Override
+  protected Pair<Option<Dataset<Row>>, String> fetchNextBatch(Option<String> 
lastCkptStr, long sourceLimit) throws HoodieException {
+    try {
+      DataSourceUtils.checkRequiredProperties(props, Arrays.asList(Config.URL, 
Config.DRIVER_CLASS, Config.USER, Config.RDBMS_TABLE_NAME, 
Config.IS_INCREMENTAL));
+      return fetch(lastCkptStr, sourceLimit);
+    } catch (Exception e) {
+      LOG.error("Exception while running JDBCSource ", e);
+      throw new HoodieException(e);
+    }
+  }
+
+  /**
+   * Decide to do a full RDBMS table scan or an incremental scan based on the 
lastCkptStr. If previous checkpoint
+   * value exists then we do an incremental scan with a PPD query or else we 
do a full scan. In certain cases where the
+   * incremental query fails, we fallback to a full scan.
+   *
+   * @param lastCkptStr Last checkpoint.
+   * @return The pair of {@link Dataset} and current checkpoint.
+   */
+  private Pair<Option<Dataset<Row>>, String> fetch(Option<String> lastCkptStr, 
long sourceLimit) {
+    Dataset<Row> dataset;
+    if (lastCkptStr.isPresent() && 
!StringUtils.isNullOrEmpty(lastCkptStr.get())) {
+      dataset = incrementalFetch(lastCkptStr, sourceLimit);
+    } else {
+      LOG.info("No checkpoint references found. Doing a full rdbms table 
fetch");
+      dataset = fullFetch(sourceLimit);
+    }
+    
dataset.persist(StorageLevel.fromString(props.getString(Config.STORAGE_LEVEL, 
"MEMORY_AND_DISK_SER")));
+    boolean isIncremental = props.getBoolean(Config.IS_INCREMENTAL);
+    Pair<Option<Dataset<Row>>, String> pair = Pair.of(Option.of(dataset), 
checkpoint(dataset, isIncremental, lastCkptStr));
+    dataset.unpersist();
+    return pair;
+  }
+
+  /**
+   * Does an incremental scan with PPQ query prepared on the bases of previous 
checkpoint.
+   *
+   * @param lastCheckpoint Last checkpoint.
+   *                       Note that the records fetched will be exclusive of 
the last checkpoint (i.e. incremental column value > lastCheckpoint).
+   * @return The {@link Dataset} after incremental fetch from RDBMS.
+   */
+  private Dataset<Row> incrementalFetch(Option<String> lastCheckpoint, long 
sourceLimit) {
+    try {
+      final String ppdQuery = "(%s) rdbms_table";
+      final SqlQueryBuilder queryBuilder = SqlQueryBuilder.select("*")
+          .from(props.getString(Config.RDBMS_TABLE_NAME))
+          .where(String.format(" %s > '%s'", 
props.getString(Config.INCREMENTAL_COLUMN), lastCheckpoint.get()));
+
+      if (sourceLimit > 0) {
+        URI jdbcURI = 
URI.create(props.getString(Config.URL).substring(URI_JDBC_PREFIX.length()));
+        if (DB_LIMIT_CLAUSE.contains(jdbcURI.getScheme())) {
+          
queryBuilder.orderBy(props.getString(Config.INCREMENTAL_COLUMN)).limit(sourceLimit);
+        }
+      }
+      String query = String.format(ppdQuery, queryBuilder.toString());
+      LOG.info("PPD QUERY: " + query);
+      LOG.info(String.format("Referenced last checkpoint and prepared new 
predicate pushdown query for jdbc pull %s", query));
+      return validatePropsAndGetDataFrameReader(sparkSession, 
props).option(Config.RDBMS_TABLE_PROP, query).load();
+    } catch (Exception e) {
+      LOG.error("Error while performing an incremental fetch. Not all database 
support the PPD query we generate to do an incremental scan", e);
+      if (props.containsKey(Config.FALLBACK_TO_FULL_FETCH) && 
props.getBoolean(Config.FALLBACK_TO_FULL_FETCH)) {
+        LOG.warn("Falling back to full scan.");
+        return fullFetch(sourceLimit);
+      }
+      throw e;
+    }
+  }
+
+  /**
+   * Does a full scan on the RDBMS data source.
+   *
+   * @return The {@link Dataset} after running full scan.
+   */
+  private Dataset<Row> fullFetch(long sourceLimit) {
+    final String ppdQuery = "(%s) rdbms_table";
+    final SqlQueryBuilder queryBuilder = SqlQueryBuilder.select("*")
+        .from(props.getString(Config.RDBMS_TABLE_NAME));
+    if (sourceLimit > 0) {
+      URI jdbcURI = 
URI.create(props.getString(Config.URL).substring(URI_JDBC_PREFIX.length()));
+      if (DB_LIMIT_CLAUSE.contains(jdbcURI.getScheme())) {
+        if (props.containsKey(Config.INCREMENTAL_COLUMN)) {
+          
queryBuilder.orderBy(props.getString(Config.INCREMENTAL_COLUMN)).limit(sourceLimit);
+        } else {
+          queryBuilder.limit(sourceLimit);
+        }
+      }
+    }
+    String query = String.format(ppdQuery, queryBuilder.toString());
+    return validatePropsAndGetDataFrameReader(sparkSession, 
props).option(Config.RDBMS_TABLE_PROP, query).load();
+  }
+
+  private String checkpoint(Dataset<Row> rowDataset, boolean isIncremental, 
Option<String> lastCkptStr) {
+    try {
+      if (isIncremental) {
+        Column incrementalColumn = 
rowDataset.col(props.getString(Config.INCREMENTAL_COLUMN));
+        final String max = 
rowDataset.agg(functions.max(incrementalColumn).cast(DataTypes.StringType)).first().getString(0);
+        LOG.info(String.format("Checkpointing column %s with value: %s ", 
incrementalColumn, max));
+        if (max != null) {
+          return max;
+        }
+        return lastCkptStr.isPresent() && 
!StringUtils.isNullOrEmpty(lastCkptStr.get()) ? lastCkptStr.get() : 
StringUtils.EMPTY_STRING;
+      } else {
+        return StringUtils.EMPTY_STRING;
+      }
+    } catch (Exception e) {
+      return StringUtils.EMPTY_STRING;

Review comment:
       I thought we might throw an exception here? fallback to full fetch is 
controlled elsewhere right. can you please clarify.




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