[BugFix] MV rewrite may generate wrong plans if query only contains c…

…onstant call operators (backport #50757) (#50777) Signed-off-by: shuming.li <[email protected]> Co-authored-by: shuming.li <[email protected]>
StarRocks · Sep 9, 2024 · dd82d0f · dd82d0f
1 parent 963eac4
commit dd82d0f
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diff --git a/...ava/com/starrocks/sql/optimizer/rule/transformation/materialization/EquationRewriter.java b/...ava/com/starrocks/sql/optimizer/rule/transformation/materialization/EquationRewriter.java
@@ -148,7 +148,14 @@ public ScalarOperator visitCall(CallOperator call, Void context) {
                     return rewritten;
                 }
             }
-
+            // If count(1)/sum(1) cannot be rewritten by mv's defined equivalents, return null directly,
+            // otherwise it may cause a wrong plan.
+            // mv       : SELECT 1, count(distinct k1) from tbl1;
+            // query    : SELECT count(1) from tbl1;
+            // MV should not rewrite the query.
+            if (call.isAggregate() && call.isConstant()) {
+                return null;
+            }
             return super.visitCall(call, context);
         }
 

diff --git a/fe/fe-core/src/test/java/com/starrocks/planner/MaterializedViewManualTest.java b/fe/fe-core/src/test/java/com/starrocks/planner/MaterializedViewManualTest.java
@@ -356,4 +356,46 @@ public void testRewriteWithCaseWhen() {
             }
         });
     }
+
+    @Test
+    public void testWrongMVRewrite() throws Exception {
+        starRocksAssert.withTable("CREATE TABLE `tbl1` (\n" +
+                "  `k1` date,\n" +
+                "  `k2` decimal64(18, 2),\n" +
+                "  `k3` varchar(255),\n" +
+                "  `v1` varchar(255)\n" +
+                ") ENGINE=OLAP \n" +
+                "DUPLICATE KEY(`k1`, `k2`, `k3`)\n" +
+                "DISTRIBUTED BY RANDOM\n" +
+                "PROPERTIES (\n" +
+                "\"replication_num\" = \"1\"\n" +
+                ");");
+        {
+            starRocksAssert.withMaterializedView("CREATE MATERIALIZED VIEW `mv1` \n" +
+                    "DISTRIBUTED BY RANDOM\n" +
+                    "REFRESH ASYNC\n" +
+                    "PROPERTIES (\n" +
+                    "\"replication_num\" = \"1\"\n" +
+                    ")\n" +
+                    "AS SELECT 1, count(distinct k1) from tbl1");
+            sql("select count(distinct k1) from tbl1").contains("mv1");
+            sql("select count(1) from tbl1").notContain("mv1");
+            sql("select count(*) from tbl1").notContain("mv1");
+            starRocksAssert.dropMaterializedView("mv1");
+        }
+        {
+            starRocksAssert.withMaterializedView("CREATE MATERIALIZED VIEW `mv1` \n" +
+                    "DISTRIBUTED BY RANDOM\n" +
+                    "REFRESH ASYNC\n" +
+                    "PROPERTIES (\n" +
+                    "\"replication_num\" = \"1\"\n" +
+                    ")\n" +
+                    "AS SELECT 1, count(1) from tbl1");
+            sql("select count(distinct k1) from tbl1").notContain("mv1");
+            sql("select count(1) from tbl1").contains("mv1");
+            sql("select count(*) from tbl1").contains("mv1");
+            starRocksAssert.dropMaterializedView("mv1");
+        }
+        starRocksAssert.dropTable("tbl1");
+    }
 }