jackjlli commented on code in PR #8483:
URL: https://github.com/apache/pinot/pull/8483#discussion_r856594342
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pinot-controller/src/main/java/org/apache/pinot/controller/helix/core/assignment/instance/InstanceReplicaGroupPartitionSelector.java:
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@@ -180,14 +266,110 @@ public void selectInstances(Map<Integer,
List<InstanceConfig>> poolToInstanceCon
numInstancesToSelect = numInstanceConfigs;
}
- List<String> instancesToSelect = new ArrayList<>(numInstancesToSelect);
- for (int i = 0; i < numInstancesToSelect; i++) {
- instancesToSelect.add(instanceConfigs.get(i).getInstanceName());
+ List<String> instancesToSelect;
+ if (_replicaGroupPartitionConfig.isMinimizeDataMovement() &&
_existingInstancePartitions != null) {
+ // Minimize data movement.
+ List<String> existingInstances =
_existingInstancePartitions.getInstances(0, 0);
+ Set<String> candidateInstances = new LinkedHashSet<>();
+ instanceConfigs.forEach(k ->
candidateInstances.add(k.getInstanceName()));
+ instancesToSelect =
+ getInstancesWithMinimumMovement(numInstancesToSelect,
candidateInstances, existingInstances);
+ } else {
+ // Select instances sequentially.
+ instancesToSelect = new ArrayList<>(numInstancesToSelect);
+ for (int i = 0; i < numInstancesToSelect; i++) {
+ instancesToSelect.add(instanceConfigs.get(i).getInstanceName());
+ }
}
instancesToSelect.sort(null);
LOGGER.info("Selecting instances: {} for table: {}", instancesToSelect,
_tableNameWithType);
// Set the instances as partition 0 replica 0
instancePartitions.setInstances(0, 0, instancesToSelect);
}
}
+
+ /**
+ * Select instances with minimum movement.
+ * This algorithm can solve the following scenarios:
Review Comment:
TODO comments added.
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