Reuse blocks for dictionaries

Author: pettyjamesm

core/trino-main/src/main/java/io/trino/operator/FlatGroupByHash.java

@@ -403,11 +403,10 @@ public AddDictionaryPageWork(Block[] blocks)
         {
             verify(canProcessDictionary(blocks), "invalid call to addDictionaryPage");
             this.dictionaryBlock = (DictionaryBlock) blocks[0];
-
-            this.dictionaries = Arrays.stream(blocks)
-                    .map(block -> (DictionaryBlock) block)
-                    .map(DictionaryBlock::getDictionary)
-                    .toArray(Block[]::new);
+            this.dictionaries = blocks;
+            for (int i = 0; i < dictionaries.length; i++) {
+                dictionaries[i] = ((DictionaryBlock) dictionaries[i]).getDictionary();
+            }
             updateDictionaryLookBack(dictionaries[0]);
         }
 
@@ -630,13 +629,12 @@ public GetDictionaryGroupIdsWork(Block[] blocks)
             verify(canProcessDictionary(blocks), "invalid call to processDictionary");
 
             this.dictionaryBlock = (DictionaryBlock) blocks[0];
-            this.groupIds = new int[dictionaryBlock.getPositionCount()];
-
-            this.dictionaries = Arrays.stream(blocks)
-                    .map(block -> (DictionaryBlock) block)
-                    .map(DictionaryBlock::getDictionary)
-                    .toArray(Block[]::new);
+            this.dictionaries = blocks;
+            for (int i = 0; i < dictionaries.length; i++) {
+                dictionaries[i] = ((DictionaryBlock) dictionaries[i]).getDictionary();
+            }
             updateDictionaryLookBack(dictionaries[0]);
+            this.groupIds = new int[dictionaryBlock.getPositionCount()];
         }
 
         @Override