hudi/rfc/rfc-55/rfc-55.md

RFC-55: Improve hudi-sync classes design and simplify configs

Proposers

• @<proposer1 @fengjian428>
• @<proposer2 @xushiyan>

Approvers

• @<approver1 @vinothchandar>
• @<approver2 @codope>

Status

JIRA: HUDI-3730

Abstract

Hudi support sync to various metastores via different processing framework like Spark, Flink, and Kafka connect.

There are some room for improvement

• The way to generate Sync configs are inconsistent in different framework
• The abstraction of SyncClasses was designed for HiveSync, hence there are duplicated code, unused method, and parameters.

We need a standard way to run hudi sync. We also need a unified abstraction of XXXSyncTool , XXXSyncClient and XXXSyncConfig to handle supported metastores, like hive metastore, bigquery, datahub, etc.

Classes design

Below are the proposed key classes to handle the main sync logic. They are extensible for different metastores.

HoodieSyncTool

Renamed from AbstractSyncTool.

public abstract class HoodieSyncTool implements AutoCloseable {

  protected HoodieSyncClient syncClient;

  /**
   * Sync tool class is the entrypoint to run meta sync.
   *
   * @param props A bag of properties passed by users. It can contain all hoodie.* and any other config.
   * @param hadoopConf Hadoop specific configs.
   */
  public HoodieSyncTool(Properties props, Configuration hadoopConf);

  public abstract void syncHoodieTable();

  public static void main(String[] args) {
     // instantiate HoodieSyncConfig and concrete sync tool, and run sync.
  }
}

HoodieSyncConfig

public class HoodieSyncConfig extends HoodieConfig {

  public static class HoodieSyncConfigParams {
    // POJO class to take command line parameters
    @Parameter()
    private String basePath; // common essential parameters

    public Properties toProps();
  }

   /**
    * XXXSyncConfig is meant to be created and used by XXXSyncTool exclusively and internally.
    * 
    * @param props passed from XXXSyncTool.
    * @param hadoopConf passed from XXXSyncTool.
    */
  public HoodieSyncConfig(Properties props, Configuration hadoopConf);
}

public class HiveSyncConfig extends HoodieSyncConfig {

  public static class HiveSyncConfigParams {

    @Parameter()
    private String syncMode;

    // delegate common parameters to other XXXParams class
    // this overcomes single-inheritance's inconvenience
    // see https://jcommander.org/#_parameter_delegates
    @ParametersDelegate()
    private HoodieSyncConfigParams hoodieSyncConfigParams = new HoodieSyncConfigParams();

    public Properties toProps();
  }

  public HoodieSyncConfig(Properties props);
}

HoodieSyncClient

Renamed from AbstractSyncHoodieClient.

public abstract class HoodieSyncClient implements AutoCloseable {
  // metastore-agnostic APIs
}

Config simplification

Compatible changes

• support all sync related configs to use suffix as hoodie.meta.sync.*
  • move hoodie.meta_sync.* or any other variance to alias
  • rename module hudi-sync to hudi-meta-sync (no bundle name change)
  • rename hoodieSync* variables or methods to hoodieMetaSync*
• database and table should not be required by sync tool; they should be inferred from table properties
• users should not need to set PartitionValueExtractor; partition value extractors should be inferred automatically
• infer repeated sync configs from original configs
  • META_SYNC_BASE_FILE_FORMAT
    • infer from org.apache.hudi.common.table.HoodieTableConfig.BASE_FILE_FORMAT
  • META_SYNC_ASSUME_DATE_PARTITION
    • infer from org.apache.hudi.common.config.HoodieMetadataConfig.ASSUME_DATE_PARTITIONING
  • META_SYNC_DECODE_PARTITION
    • infer from org.apache.hudi.common.table.HoodieTableConfig.URL_ENCODE_PARTITIONING
  • META_SYNC_USE_FILE_LISTING_FROM_METADATA
    • infer from org.apache.hudi.common.config.HoodieMetadataConfig.ENABLE

Breaking changes

The breaking changes should be made at once together with other user-facing config changes at a chosen proper release.

• remove all sync related option constants from DataSourceOptions
• remove USE_JDBC and fully adopt SYNC_MODE
• remove HIVE_SYNC_ENDABLED and related arguments from sync tools and delta streamers. Use SYNC_ENABLED
• remove repeated sync configs, use original configs
  • META_SYNC_BASE_FILE_FORMAT -> org.apache.hudi.common.table.HoodieTableConfig.BASE_FILE_FORMAT
  • META_SYNC_ASSUME_DATE_PARTITION -> org.apache.hudi.common.config.HoodieMetadataConfig.ASSUME_DATE_PARTITIONING
  • META_SYNC_DECODE_PARTITION -> org.apache.hudi.common.table.HoodieTableConfig.URL_ENCODE_PARTITIONING
  • META_SYNC_USE_FILE_LISTING_FROM_METADATA -> org.apache.hudi.common.config.HoodieMetadataConfig.ENABLE

Rollout/Adoption Plan

• Users who set USE_JDBC will need to change to set SYNC_MODE=jdbc
• Users who set --enable-hive-sync or HIVE_SYNC_ENABLED will need to drop the argument or config and change to --enable-sync or SYNC_ENABLED.
• Users who import from DataSourceOptions for meta sync constants will need to import relevant configs from HoodieSyncConfig and subclasses.
• Users who set AwsGlueCatalogSyncTool as sync tool class need to update the class name to AWSGlueCatalogSyncTool

Test Plan

• CI covers most operations for Hive sync with HMS
• end-to-end testing with setup for Glue Catalog, BigQuery, DataHub instance
• manual testing with partitions added and removed