[MySQL Compatibility 1/4][Bug] Fix bug that set sql_mode with concat() function failed

fe/fe-core/src/main/java/org/apache/doris/analysis/ExpressionFunctions.java

@@ -22,6 +22,8 @@
 import org.apache.doris.catalog.ScalarType;
 import org.apache.doris.catalog.Type;
 import org.apache.doris.common.AnalysisException;
+import org.apache.doris.qe.ConnectContext;
+import org.apache.doris.qe.VariableMgr;
 import org.apache.doris.rewrite.FEFunction;
 import org.apache.doris.rewrite.FEFunctions;
 
@@ -56,18 +58,18 @@ private ExpressionFunctions() {
     public Expr evalExpr(Expr constExpr) {
         // Function's arg are all LiteralExpr.
         for (Expr child : constExpr.getChildren()) {
-            if (!(child instanceof LiteralExpr)) {
+            if (!(child instanceof LiteralExpr) && !(child instanceof SysVariableDesc)) {
                 return constExpr;
             }
         }
 
         if (constExpr instanceof ArithmeticExpr
-                || constExpr instanceof FunctionCallExpr 
+                || constExpr instanceof FunctionCallExpr
                 || constExpr instanceof TimestampArithmeticExpr) {
             Function fn = constExpr.getFn();
-            
+
             Preconditions.checkNotNull(fn, "Expr's fn can't be null.");
-            
+
             // return NullLiteral directly iff:
             // 1. Not UDF
             // 2. Not in NonNullResultWithNullParamFunctions
@@ -96,6 +98,14 @@ public Expr evalExpr(Expr constExpr) {
                     return constExpr;
                 }
             }
+        } else if (constExpr instanceof SysVariableDesc) {
+            try {
+                VariableMgr.fillValue(ConnectContext.get().getSessionVariable(), (SysVariableDesc) constExpr);
+                return ((SysVariableDesc) constExpr).getLiteralExpr();
+            } catch (AnalysisException e) {
+                LOG.warn("failed to get session variable value: " + ((SysVariableDesc) constExpr).getName());
+                return constExpr;
+            }
         }
         return constExpr;
     }

fe/fe-core/src/main/java/org/apache/doris/analysis/SetVar.java

@@ -17,7 +17,6 @@
 
 package org.apache.doris.analysis;
 
-import com.google.common.base.Strings;
 import org.apache.doris.catalog.Catalog;
 import org.apache.doris.common.AnalysisException;
 import org.apache.doris.common.ErrorCode;
@@ -30,6 +29,8 @@
 import org.apache.doris.qe.SessionVariable;
 import org.apache.doris.system.HeartbeatFlags;
 
+import com.google.common.base.Strings;
+
 // change one variable.
 public class SetVar {
 

fe/fe-core/src/main/java/org/apache/doris/analysis/SysVariableDesc.java

@@ -17,7 +17,6 @@
 
 package org.apache.doris.analysis;
 
-import com.google.common.base.Strings;
 import org.apache.doris.catalog.Type;
 import org.apache.doris.common.AnalysisException;
 import org.apache.doris.common.DdlException;
@@ -32,6 +31,8 @@
 import org.apache.doris.thrift.TIntLiteral;
 import org.apache.doris.thrift.TStringLiteral;
 
+import com.google.common.base.Strings;
+
 // System variable
 // Converted to StringLiteral in analyze, if this variable is not exist, throw AnalysisException.
 public class SysVariableDesc extends Expr {
@@ -42,6 +43,8 @@ public class SysVariableDesc extends Expr {
     private double floatValue;
     private String strValue;
 
+    private LiteralExpr literalExpr;
+
     public SysVariableDesc(String name) {
         this(name, SetType.SESSION);
     }
@@ -89,18 +92,48 @@ public SetType getSetType() {
 
     public void setBoolValue(boolean value) {
         this.boolValue = value;
+        this.literalExpr = new BoolLiteral(value);
     }
 
     public void setIntValue(long value) {
         this.intValue = value;
+        this.literalExpr = new IntLiteral(value);
     }
 
     public void setFloatValue(double value) {
         this.floatValue = value;
+        this.literalExpr = new FloatLiteral(value);
     }
 
     public void setStringValue(String value) {
         this.strValue = value;
+        this.literalExpr = new StringLiteral(value);
+    }
+
+    public Expr getLiteralExpr() {
+        return this.literalExpr;
+    }
+
+    @Override
+    public Expr getResultValue() throws AnalysisException {
+        Expr expr = super.getResultValue();
+        if (!Strings.isNullOrEmpty(name) && name.equalsIgnoreCase(SessionVariable.SQL_MODE)) {
+            // SQL_MODE is a special variable. Its type is int, but it is usually set using a string.
+            // Such as `set sql_mode =  concat(@@sql_mode, "STRICT_TRANS_TABLES");`
+            // So we return the string type here so that it can correctly match the subsequent function signature.
+            // We will convert the string to int in VariableMgr.
+            try {
+                return new StringLiteral(SqlModeHelper.decode(intValue));
+            } catch (DdlException e) {
+                throw new AnalysisException(e.getMessage());
+            }
+        }
+        return expr;
+    }
+
+    @Override
+    protected boolean isConstantImpl() {
+        return true;
     }
 
     @Override

fe/fe-core/src/test/java/org/apache/doris/analysis/SetVariableTest.java

@@ -0,0 +1,63 @@
+// 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.doris.analysis;
+
+import org.apache.doris.qe.ConnectContext;
+import org.apache.doris.qe.SqlModeHelper;
+import org.apache.doris.qe.StmtExecutor;
+import org.apache.doris.utframe.UtFrameUtils;
+
+import org.junit.Assert;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import java.util.UUID;
+
+public class SetVariableTest {
+    // use a unique dir so that it won't be conflict with other unit test which
+    // may also start a Mocked Frontend
+    private static String runningDir = "fe/mocked/QueryPlanTest/" + UUID.randomUUID().toString() + "/";
+
+    private static ConnectContext connectContext;
+
+    @BeforeClass
+    public static void beforeClass() throws Exception {
+        UtFrameUtils.createMinDorisCluster(runningDir);
+        // create connect context
+        connectContext = UtFrameUtils.createDefaultCtx();
+    }
+
+    @Test
+    public void testSqlMode() throws Exception {
+        String setStr = "set sql_mode = concat(@@sql_mode, 'STRICT_TRANS_TABLES');";
+        connectContext.getState().reset();
+        StmtExecutor stmtExecutor = new StmtExecutor(connectContext, setStr);
+        stmtExecutor.execute();
+        Assert.assertEquals("STRICT_TRANS_TABLES",
+                SqlModeHelper.decode(connectContext.getSessionVariable().getSqlMode()));
+    }
+
+    @Test
+    public void testExecMemLimit() throws Exception {
+        String setStr = "set exec_mem_limit = @@exec_mem_limit * 10";
+        connectContext.getState().reset();
+        StmtExecutor stmtExecutor = new StmtExecutor(connectContext, setStr);
+        stmtExecutor.execute();
+        Assert.assertEquals(21474836480L, connectContext.getSessionVariable().getMaxExecMemByte());
+    }
+}

fe/fe-core/src/test/java/org/apache/doris/planner/QueryPlanTest.java

@@ -17,7 +17,6 @@
 
 package org.apache.doris.planner;
 
-import com.google.common.collect.Lists;
 import org.apache.doris.analysis.CreateDbStmt;
 import org.apache.doris.analysis.CreateTableStmt;
 import org.apache.doris.analysis.DropDbStmt;
@@ -47,6 +46,8 @@
 import org.junit.BeforeClass;
 import org.junit.Test;
 
+import com.google.common.collect.Lists;
+
 import java.io.File;
 import java.util.List;
 import java.util.UUID;