marton-bod commented on a change in pull request #2407:
URL: https://github.com/apache/iceberg/pull/2407#discussion_r608586651
##########
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:
It does not really have any cost. On the first ever call to `inverse()`,
it creates the `Inverse` object (and then caches it) which is just a wrapper on
the original data structure, which reimplements the `get()` method to query the
the same data in the opposite direction.
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