Avoid creating new objects when region is same as original page

trinodb · May 8, 2023 · 122f513 · 122f513
1 parent 16eca5e
commit 122f513
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Showing 2 changed files with 8 additions and 1 deletion.
diff --git a/core/trino-spi/src/main/java/io/trino/spi/Page.java b/core/trino-spi/src/main/java/io/trino/spi/Page.java
@@ -153,6 +153,10 @@ public Page getRegion(int positionOffset, int length)
             throw new IndexOutOfBoundsException(format("Invalid position %s and length %s in page with %s positions", positionOffset, length, positionCount));
         }
 
+        if (positionOffset == 0 && length == positionCount) {
+            return this;
+        }
+
         int channelCount = getChannelCount();
         Block[] slicedBlocks = new Block[channelCount];
         for (int i = 0; i < channelCount; i++) {

diff --git a/core/trino-spi/src/test/java/io/trino/spi/TestPage.java b/core/trino-spi/src/test/java/io/trino/spi/TestPage.java
@@ -32,14 +32,17 @@
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
 import static org.testng.Assert.assertEquals;
 import static org.testng.Assert.assertNotEquals;
+import static org.testng.Assert.assertSame;
 import static org.testng.Assert.assertTrue;
 
 public class TestPage
 {
     @Test
     public void testGetRegion()
     {
-        assertEquals(new Page(10).getRegion(5, 5).getPositionCount(), 5);
+        Page page = new Page(10);
+        assertEquals(page.getRegion(5, 5).getPositionCount(), 5);
+        assertSame(page.getRegion(0, 10), page);
     }
 
     @Test