[GitHub] [iceberg] chenjunjiedada commented on a diff in pull request #7077: Flink 1.16: Change distribution modes

["chenjunjiedada (via GitHub)" <gi...@apache.org>]

chenjunjiedada commented on code in PR #7077:
URL: https://github.com/apache/iceberg/pull/7077#discussion_r1133170289


##########
flink/v1.16/flink/src/main/java/org/apache/iceberg/flink/FlinkWriteConf.java:
##########
@@ -153,16 +167,89 @@ public String orcCompressionStrategy() {
         .parse();
   }
 
-  public DistributionMode distributionMode() {
+  public DistributionMode distributionMode(
+      List<Integer> equalityFieldIds, List<String> equalityFieldColumns) {
     String modeName =
         confParser
             .stringConf()
             .option(FlinkWriteOptions.DISTRIBUTION_MODE.key())
             .flinkConfig(FlinkWriteOptions.DISTRIBUTION_MODE)
             .tableProperty(TableProperties.WRITE_DISTRIBUTION_MODE)
-            .defaultValue(TableProperties.WRITE_DISTRIBUTION_MODE_NONE)
-            .parse();
-    return DistributionMode.fromName(modeName);
+            .parseOptional();
+
+    DistributionMode writeMode =
+        modeName == null
+            ? defaultWriteDistributionMode(equalityFieldIds)
+            : DistributionMode.fromName(modeName);
+
+    switch (writeMode) {
+      case NONE:
+        if (equalityFieldIds.isEmpty()) {
+          return NONE;
+        } else {
+          LOG.warn("Switch to use 'hash' distribution mode, because there are equality fields set");
+          return HASH;
+        }
+
+      case HASH:
+        PartitionSpec partitionSpec = table.spec();
+        if (equalityFieldIds.isEmpty()) {
+          if (partitionSpec.isUnpartitioned()) {
+            LOG.warn(
+                "Fallback to use 'none' distribution mode, because there are no equality fields set and table is unpartitioned");
+            return NONE;
+          }
+        } else {
+          if (partitionSpec.isPartitioned()) {
+            for (PartitionField partitionField : partitionSpec.fields()) {
+              Preconditions.checkState(
+                  equalityFieldIds.contains(partitionField.sourceId()),
+                  "In 'hash' distribution mode with equality fields set, partition field '%s' "
+                      + "should be included in equality fields: '%s'",
+                  partitionField,
+                  equalityFieldColumns);
+            }
+          }
+        }
+        return HASH;
+
+      case RANGE:

Review Comment:
   If the sort order is defined, it would be better to throw an exception to tell the user that flink writer can't guarantee the order rather than fallback to these writers. 



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