[GitHub] [druid] clintropolis commented on a change in pull request #12073: Update Aggregator and AggregatorFactory interfaces to improve mem estimates

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clintropolis commented on a change in pull request #12073:
URL: https://github.com/apache/druid/pull/12073#discussion_r783009496



##########
File path: processing/src/main/java/org/apache/druid/segment/DimensionDictionary.java
##########
@@ -160,4 +173,16 @@ public int getIdForNull()
       lock.readLock().unlock();
     }
   }
+
+  private long getObjectSize(@Nonnull T object)

Review comment:
       hmm, this method is presumptuous and breaks the contract of this class being generic. I think a size estimator function should be passed into this method, it needs to be public so that callers can override it, or maybe it should be abstract and some `StringDimensionDictionary` should be implemented to minimize function calls since its going to be a pretty hot method

##########
File path: processing/src/main/java/org/apache/druid/query/aggregation/AggregatorAndSize.java
##########
@@ -0,0 +1,49 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.query.aggregation;
+
+/**
+ * Encapsulates an {@link Aggregator} and the initial size in bytes required by
+ * the Aggregator.
+ */
+public class AggregatorAndSize
+{
+
+  // TODO: include default overhead for object sizes

Review comment:
       nit: unresolved todo

##########
File path: processing/src/main/java/org/apache/druid/segment/DimensionIndexer.java
##########
@@ -127,7 +127,7 @@
    * @return An array containing an encoded representation of the input row value.
    */
   @Nullable
-  EncodedKeyComponentType processRowValsToUnsortedEncodedKeyComponent(@Nullable Object dimValues, boolean reportParseExceptions);
+  EncodedDimensionValue<EncodedKeyComponentType> processRowValsToUnsortedEncodedKeyComponent(@Nullable Object dimValues, boolean reportParseExceptions);

Review comment:
       nit: javadoc params and return type needs updated.. but this isn't really new, it basically needed updated long ago, it is not always an array 😅 

##########
File path: server/src/main/java/org/apache/druid/segment/realtime/plumber/RealtimePlumber.java
##########
@@ -271,6 +271,7 @@ private Sink getSink(long timestamp)
           config.getAppendableIndexSpec(),
           config.getMaxRowsInMemory(),
           config.getMaxBytesInMemoryOrDefault(),
+          true,

Review comment:
       i've noticed a few places that aren't wired up to config are using true, so using the new behavior with no way out, is that intentional? this one in particular probably doesn't matter all that much these days (i hope), but i'm less sure about all of them, and it isn't consistent because i see some hard coded false in there too

##########
File path: processing/src/main/java/org/apache/druid/segment/incremental/IncrementalIndex.java
##########
@@ -557,12 +573,17 @@ IncrementalIndexRowResult toIncrementalIndexRow(InputRow row)
         DimensionIndexer indexer = desc.getIndexer();
         Object dimsKey = null;
         try {
-          dimsKey = indexer.processRowValsToUnsortedEncodedKeyComponent(row.getRaw(dimension), true);
+          final EncodedDimensionValue<?> encodedDimensionValue
+              = indexer.processRowValsToUnsortedEncodedKeyComponent(row.getRaw(dimension), true);

Review comment:
       i guess due to the way this refactor was done (compared to aggs) there is no real way to turn off calculating the estimates, even if we aren't using them. maybe it doesn't matter if there is no/minimal performance impact




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