Don't rewrite IF to CASE

prestodb · Apr 20, 2021 · 413584a · 413584a
1 parent d0e46d5
commit 413584a
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diff --git a/...n/java/com/facebook/presto/sql/planner/iterative/rule/CanonicalizeExpressionRewriter.java b/...n/java/com/facebook/presto/sql/planner/iterative/rule/CanonicalizeExpressionRewriter.java
@@ -19,17 +19,12 @@
 import com.facebook.presto.sql.tree.ExpressionTreeRewriter;
 import com.facebook.presto.sql.tree.Extract;
 import com.facebook.presto.sql.tree.FunctionCall;
-import com.facebook.presto.sql.tree.IfExpression;
 import com.facebook.presto.sql.tree.IsNotNullPredicate;
 import com.facebook.presto.sql.tree.IsNullPredicate;
 import com.facebook.presto.sql.tree.NotExpression;
 import com.facebook.presto.sql.tree.QualifiedName;
-import com.facebook.presto.sql.tree.SearchedCaseExpression;
-import com.facebook.presto.sql.tree.WhenClause;
 import com.google.common.collect.ImmutableList;
 
-import java.util.Optional;
-
 public class CanonicalizeExpressionRewriter
 {
     private CanonicalizeExpressionRewriter() {}
@@ -49,17 +44,6 @@ public Expression rewriteIsNotNullPredicate(IsNotNullPredicate node, Void contex
             return new NotExpression(new IsNullPredicate(value));
         }
 
-        @Override
-        public Expression rewriteIfExpression(IfExpression node, Void context, ExpressionTreeRewriter<Void> treeRewriter)
-        {
-            Expression condition = treeRewriter.rewrite(node.getCondition(), context);
-            Expression trueValue = treeRewriter.rewrite(node.getTrueValue(), context);
-
-            Optional<Expression> falseValue = node.getFalseValue().map((value) -> treeRewriter.rewrite(value, context));
-
-            return new SearchedCaseExpression(ImmutableList.of(new WhenClause(condition, trueValue)), falseValue);
-        }
-
         @Override
         public Expression rewriteCurrentTime(CurrentTime node, Void context, ExpressionTreeRewriter<Void> treeRewriter)
         {

diff --git a/presto-main/src/test/java/com/facebook/presto/sql/TestExpressionInterpreter.java b/presto-main/src/test/java/com/facebook/presto/sql/TestExpressionInterpreter.java
@@ -1210,10 +1210,6 @@ public void testIf()
         assertOptimizedEquals("IF(false, 1.01, 1.02)", "1.02");
         assertOptimizedEquals("IF(true, 1234567890.123, 1.02)", "1234567890.123");
         assertOptimizedEquals("IF(false, 1.01, 1234567890.123)", "1234567890.123");
-
-        // todo optimize case statement
-        assertOptimizedEquals("IF(unbound_boolean, 1 + 2, 3 + 4)", "CASE WHEN unbound_boolean THEN (1 + 2) ELSE (3 + 4) END");
-        assertOptimizedEquals("IF(unbound_boolean, BIGINT '1' + 2, 3 + 4)", "CASE WHEN unbound_boolean THEN (BIGINT '1' + 2) ELSE (3 + 4) END");
     }
 
     @Test
@@ -1351,9 +1347,6 @@ public void testBind()
     @Test
     public void testFailedExpressionOptimization()
     {
-        assertOptimizedEquals("if(unbound_boolean, 1, 0 / 0)", "CASE WHEN unbound_boolean THEN 1 ELSE 0 / 0 END");
-        assertOptimizedEquals("if(unbound_boolean, 0 / 0, 1)", "CASE WHEN unbound_boolean THEN 0 / 0 ELSE 1 END");
-
         assertOptimizedMatches("CASE unbound_long WHEN 1 THEN 1 WHEN 0 / 0 THEN 2 END",
                 "CASE unbound_long WHEN BIGINT '1' THEN 1 WHEN cast(fail(8, 'ignored failure message') as bigint) THEN 2 END");
 

diff --git a/...va/com/facebook/presto/sql/planner/iterative/rule/TestCanonicalizeExpressionRewriter.java b/...va/com/facebook/presto/sql/planner/iterative/rule/TestCanonicalizeExpressionRewriter.java
@@ -27,12 +27,6 @@ public void testRewriteIsNotNullPredicate()
         assertRewritten("x is NOT NULL", "NOT (x IS NULL)");
     }
 
-    @Test
-    public void testRewriteIfExpression()
-    {
-        assertRewritten("IF(x = 0, 0, 1)", "CASE WHEN x = 0 THEN 0 ELSE 1 END");
-    }
-
     @Test
     public void testRewriteCurrentTime()
     {