[GitHub] [iceberg] pvary commented on a change in pull request #2407: Hive: Synchronize equivalent HMS and Iceberg properties

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

pvary commented on a change in pull request #2407:
URL: https://github.com/apache/iceberg/pull/2407#discussion_r608361767



##########
File path: hive-metastore/src/main/java/org/apache/iceberg/hive/HiveTableOperations.java
##########
@@ -86,6 +90,28 @@
       .impl(HiveMetaStoreClient.class, "alter_table",
           String.class, String.class, Table.class, EnvironmentContext.class)
       .build();
+  private static final BiMap<String, String> ICEBERG_TO_HMS_TRANSLATION = ImmutableBiMap.of(
+      // gc.enabled in Iceberg and external.table.purge in Hive are meant to do the same things but with different names
+      GC_ENABLED, "external.table.purge"
+  );
+
+
+  /**
+   * Provides key translation where necessary between Iceberg and HMS props. This translation is needed because some
+   * properties control the same behaviour but are named differently in Iceberg and Hive. Therefore changes to these
+   * property pairs should be synchronized.
+   *
+   * Example: Deleting data files upon DROP TABLE is enabled using gc.enabled=true in Iceberg and
+   * external.table.purge=true in Hive. Hive and Iceberg users are unaware of each other's control flags, therefore
+   * inconsistent behaviour can occur from e.g. a Hive user's point of view if external.table.purge=true is set on the
+   * HMS table but gc.enabled=false is set on the Iceberg table, resulting in no data file deletion.
+   *
+   * @param hmsProp The HMS property that should be translated to Iceberg property
+   * @return Iceberg property equivalent to the hmsProp. If no such translation exists, the original hmsProp is returned
+   */
+  public static String translateToIcebergProp(String hmsProp) {
+    return ICEBERG_TO_HMS_TRANSLATION.inverse().getOrDefault(hmsProp, hmsProp);

Review comment:
       How costly  is the inverse call?




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