improved sql parser.

src/main/java/com/alibaba/druid/sql/SQLUtils.java

@@ -24,6 +24,7 @@ import com.alibaba.druid.sql.ast.statement.*;
 import com.alibaba.druid.sql.dialect.db2.visitor.DB2OutputVisitor;
 import com.alibaba.druid.sql.dialect.db2.visitor.DB2SchemaStatVisitor;
 import com.alibaba.druid.sql.dialect.h2.visitor.H2OutputVisitor;
+import com.alibaba.druid.sql.dialect.h2.visitor.H2SchemaStatVisitor;
 import com.alibaba.druid.sql.dialect.mysql.visitor.MySqlOutputVisitor;
 import com.alibaba.druid.sql.dialect.mysql.visitor.MySqlSchemaStatVisitor;
 import com.alibaba.druid.sql.dialect.odps.visitor.OdpsOutputVisitor;
@@ -402,8 +403,7 @@ public class SQLUtils {
         }
 
         if (JdbcConstants.MYSQL.equals(dbType) || //
-                JdbcConstants.MARIADB.equals(dbType) || //
-                JdbcConstants.H2.equals(dbType)) {
+                JdbcConstants.MARIADB.equals(dbType)) {
             return new MySqlSchemaStatVisitor();
         }
 
@@ -423,6 +423,10 @@ public class SQLUtils {
             return new OdpsSchemaStatVisitor();
         }
 
+        if (JdbcConstants.H2.equals(dbType)) {
+            return new H2SchemaStatVisitor();
+        }
+
         return new SchemaStatVisitor();
     }
 

src/main/java/com/alibaba/druid/sql/ast/statement/SQLReplaceStatement.java

@@ -1,3 +1,18 @@
+/*
+ * Copyright 1999-2017 Alibaba Group Holding Ltd.
+ *
+ * Licensed 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 com.alibaba.druid.sql.ast.statement;
 
 import com.alibaba.druid.sql.ast.SQLExpr;

src/main/java/com/alibaba/druid/sql/ast/statement/SQLSelectQueryBlock.java

@@ -25,36 +25,36 @@ import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 import com.alibaba.druid.util.FnvHash;
 
 public class SQLSelectQueryBlock extends SQLObjectImpl implements SQLSelectQuery, SQLReplaceable {
-    private boolean                     bracket         = false;
-    protected int                       distionOption;
-    protected final List<SQLSelectItem> selectList      = new ArrayList<SQLSelectItem>();
+    private boolean                      bracket         = false;
+    protected int                        distionOption;
+    protected final List<SQLSelectItem>  selectList      = new ArrayList<SQLSelectItem>();
 
-    protected SQLTableSource            from;
-    protected SQLExprTableSource        into;
-    protected SQLExpr                   where;
+    protected SQLTableSource             from;
+    protected SQLExprTableSource         into;
+    protected SQLExpr                    where;
 
     // for oracle & oceanbase
-    protected SQLExpr                   startWith;
-    protected SQLExpr                   connectBy;
-    protected boolean                   prior           = false;
-    protected boolean                   noCycle         = false;
-    protected SQLOrderBy                orderBySiblings;
+    protected SQLExpr                    startWith;
+    protected SQLExpr                    connectBy;
+    protected boolean                    prior           = false;
+    protected boolean                    noCycle         = false;
+    protected SQLOrderBy                 orderBySiblings;
 
-    protected SQLSelectGroupByClause    groupBy;
-    protected SQLOrderBy                orderBy;
-    protected boolean                   parenthesized   = false;
-    protected boolean                   forUpdate       = false;
-    protected boolean                   noWait          = false;
-    protected SQLExpr                   waitTime;
-
-    protected SQLLimit                  limit;
+    protected SQLSelectGroupByClause     groupBy;
+    protected SQLOrderBy                 orderBy;
+    protected boolean                    parenthesized   = false;
+    protected boolean                    forUpdate       = false;
+    protected boolean                    noWait          = false;
+    protected SQLExpr                    waitTime;
+    protected SQLLimit                   limit;
 
     // for oracle
-    protected List<SQLExpr>             forUpdateOf;
-
-    protected List<SQLExpr>             distributeBy;
+    protected List<SQLExpr>              forUpdateOf;
+    protected List<SQLExpr>              distributeBy;
     protected List<SQLSelectOrderByItem> sortBy;
 
+    protected String                     cachedSelectList; // optimized for SelectListCache
+
     public SQLSelectQueryBlock(){
 
     }
@@ -397,6 +397,15 @@ public class SQLSelectQueryBlock extends SQLObjectImpl implements SQLSelectQuery
         return forUpdateOf.size();
     }
 
+    public void cloneSelectListTo(SQLSelectQueryBlock x) {
+        x.distionOption = distionOption;
+        for (SQLSelectItem item : this.selectList) {
+            SQLSelectItem item2 = item.clone();
+            item2.setParent(x);
+            x.selectList.add(item2);
+        }
+    }
+
     public void cloneTo(SQLSelectQueryBlock x) {
 
         x.distionOption = distionOption;
@@ -580,4 +589,12 @@ public class SQLSelectQueryBlock extends SQLObjectImpl implements SQLSelectQuery
 
         setLimit(limit);
     }
+
+    public String getCachedSelectList() {
+        return cachedSelectList;
+    }
+
+    public void setCachedSelectList(String cachedSelectList) {
+        this.cachedSelectList = cachedSelectList;
+    }
 }

src/main/java/com/alibaba/druid/sql/dialect/db2/parser/DB2SelectParser.java

@@ -21,10 +21,7 @@ import com.alibaba.druid.sql.ast.SQLSetQuantifier;
 import com.alibaba.druid.sql.ast.statement.SQLSelectQuery;
 import com.alibaba.druid.sql.dialect.db2.ast.stmt.DB2SelectQueryBlock;
 import com.alibaba.druid.sql.dialect.db2.ast.stmt.DB2SelectQueryBlock.Isolation;
-import com.alibaba.druid.sql.parser.ParserException;
-import com.alibaba.druid.sql.parser.SQLExprParser;
-import com.alibaba.druid.sql.parser.SQLSelectParser;
-import com.alibaba.druid.sql.parser.Token;
+import com.alibaba.druid.sql.parser.*;
 
 public class DB2SelectParser extends SQLSelectParser {
 
@@ -32,6 +29,10 @@ public class DB2SelectParser extends SQLSelectParser {
         super(exprParser);
     }
 
+    public DB2SelectParser(SQLExprParser exprParser, SQLSelectListCache selectListCache){
+        super(exprParser, selectListCache);
+    }
+
     public DB2SelectParser(String sql){
         this(new DB2ExprParser(sql));
     }

src/main/java/com/alibaba/druid/sql/dialect/db2/parser/DB2StatementParser.java

@@ -39,7 +39,7 @@ public class DB2StatementParser extends SQLStatementParser {
     }
     
     public DB2SelectParser createSQLSelectParser() {
-        return new DB2SelectParser(this.exprParser);
+        return new DB2SelectParser(this.exprParser, selectListCache);
     }
     
     public boolean parseStatementListDialect(List<SQLStatement> statementList) {

src/main/java/com/alibaba/druid/sql/dialect/h2/ast/H2MergeStatement.java

@@ -1,33 +0,0 @@
-package com.alibaba.druid.sql.dialect.h2.ast;
-
-import com.alibaba.druid.sql.ast.SQLName;
-import com.alibaba.druid.sql.ast.SQLStatementImpl;
-import com.alibaba.druid.sql.ast.statement.SQLExprTableSource;
-
-import java.util.ArrayList;
-import java.util.List;
-
-public class H2MergeStatement extends SQLStatementImpl {
-    private SQLExprTableSource table;
-
-    private final List<SQLName> keyColumns = new ArrayList<SQLName>();
-
-    public SQLExprTableSource getTable() {
-        return table;
-    }
-
-    public void setTable(SQLName table) {
-        this.setTable(new SQLExprTableSource(table));
-    }
-
-    public void setTable(SQLExprTableSource table) {
-        if (table != null) {
-            table.setParent(this);
-        }
-        this.table = table;
-    }
-
-    public List<SQLName> getKeyColumns() {
-        return keyColumns;
-    }
-}

src/main/java/com/alibaba/druid/sql/dialect/h2/parser/H2ExprParser.java

@@ -1,3 +1,18 @@
+/*
+ * Copyright 1999-2017 Alibaba Group Holding Ltd.
+ *
+ * Licensed 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 com.alibaba.druid.sql.dialect.h2.parser;
 
 import com.alibaba.druid.sql.parser.Lexer;

src/main/java/com/alibaba/druid/sql/dialect/h2/parser/H2Lexer.java

@@ -1,3 +1,18 @@
+/*
+ * Copyright 1999-2017 Alibaba Group Holding Ltd.
+ *
+ * Licensed 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 com.alibaba.druid.sql.dialect.h2.parser;
 
 import com.alibaba.druid.sql.parser.Keywords;

src/main/java/com/alibaba/druid/sql/dialect/h2/parser/H2SelectParser.java

@@ -1,6 +1,22 @@
+/*
+ * Copyright 1999-2017 Alibaba Group Holding Ltd.
+ *
+ * Licensed 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 com.alibaba.druid.sql.dialect.h2.parser;
 
 import com.alibaba.druid.sql.parser.SQLExprParser;
+import com.alibaba.druid.sql.parser.SQLSelectListCache;
 import com.alibaba.druid.sql.parser.SQLSelectParser;
 
 public class H2SelectParser extends SQLSelectParser {
@@ -9,6 +25,10 @@ public class H2SelectParser extends SQLSelectParser {
         super(exprParser);
     }
 
+    public H2SelectParser(SQLExprParser exprParser, SQLSelectListCache selectListCache){
+        super(exprParser, selectListCache);
+    }
+
     public H2SelectParser(String sql){
         this(new H2ExprParser(sql));
     }

src/main/java/com/alibaba/druid/sql/dialect/h2/parser/H2StatementParser.java

@@ -1,3 +1,18 @@
+/*
+ * Copyright 1999-2017 Alibaba Group Holding Ltd.
+ *
+ * Licensed 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 com.alibaba.druid.sql.dialect.h2.parser;
 
 import com.alibaba.druid.sql.ast.SQLName;
@@ -6,7 +21,6 @@ import com.alibaba.druid.sql.ast.expr.SQLQueryExpr;
 import com.alibaba.druid.sql.ast.statement.SQLInsertStatement;
 import com.alibaba.druid.sql.ast.statement.SQLReplaceStatement;
 import com.alibaba.druid.sql.ast.statement.SQLSelect;
-import com.alibaba.druid.sql.dialect.h2.ast.H2MergeStatement;
 import com.alibaba.druid.sql.parser.*;
 import com.alibaba.druid.util.FnvHash;
 import com.alibaba.druid.util.JdbcConstants;
@@ -25,7 +39,7 @@ public class H2StatementParser extends SQLStatementParser {
     }
 
     public H2SelectParser createSQLSelectParser() {
-        return new H2SelectParser(this.exprParser);
+        return new H2SelectParser(this.exprParser, selectListCache);
     }
 
     public SQLStatement parseMerge() {

src/main/java/com/alibaba/druid/sql/dialect/h2/visitor/H2ASTVisitor.java

@@ -1,3 +1,18 @@
+/*
+ * Copyright 1999-2017 Alibaba Group Holding Ltd.
+ *
+ * Licensed 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 com.alibaba.druid.sql.dialect.h2.visitor;
 
 import com.alibaba.druid.sql.visitor.SQLASTVisitor;

src/main/java/com/alibaba/druid/sql/dialect/h2/visitor/H2ASTVisitorAdapter.java

@@ -1,3 +1,18 @@
+/*
+ * Copyright 1999-2017 Alibaba Group Holding Ltd.
+ *
+ * Licensed 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 com.alibaba.druid.sql.dialect.h2.visitor;
 
 import com.alibaba.druid.sql.visitor.SQLASTVisitorAdapter;

src/main/java/com/alibaba/druid/sql/dialect/h2/visitor/H2EvalVisitor.java

@@ -1,3 +1,18 @@
+/*
+ * Copyright 1999-2017 Alibaba Group Holding Ltd.
+ *
+ * Licensed 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 com.alibaba.druid.sql.dialect.h2.visitor;
 
 import com.alibaba.druid.sql.ast.expr.*;

src/main/java/com/alibaba/druid/sql/dialect/h2/visitor/H2OutputVisitor.java

@@ -1,3 +1,18 @@
+/*
+ * Copyright 1999-2017 Alibaba Group Holding Ltd.
+ *
+ * Licensed 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 com.alibaba.druid.sql.dialect.h2.visitor;
 
 import com.alibaba.druid.sql.ast.SQLExpr;

src/main/java/com/alibaba/druid/sql/dialect/h2/visitor/H2SchemaStatVisitor.java

@@ -1,6 +1,21 @@
+/*
+ * Copyright 1999-2017 Alibaba Group Holding Ltd.
+ *
+ * Licensed 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 com.alibaba.druid.sql.dialect.h2.visitor;
 
 import com.alibaba.druid.sql.visitor.SchemaStatVisitor;
 
 public class H2SchemaStatVisitor extends SchemaStatVisitor implements H2ASTVisitor {
-}
+}

src/main/java/com/alibaba/druid/sql/dialect/mysql/ast/statement/MySqlSelectQueryBlock.java

@@ -20,6 +20,7 @@ import java.util.List;
 
 import com.alibaba.druid.sql.SQLUtils;
 import com.alibaba.druid.sql.ast.*;
+import com.alibaba.druid.sql.ast.statement.SQLSelectItem;
 import com.alibaba.druid.sql.ast.statement.SQLSelectQueryBlock;
 import com.alibaba.druid.sql.dialect.mysql.ast.MySqlObject;
 import com.alibaba.druid.sql.dialect.mysql.visitor.MySqlASTVisitor;
@@ -28,21 +29,16 @@ import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 import oracle.sql.SQLUtil;
 
 public class MySqlSelectQueryBlock extends SQLSelectQueryBlock implements MySqlObject {
-
     private boolean              hignPriority;
     private boolean              straightJoin;
-
     private boolean              smallResult;
     private boolean              bigResult;
     private boolean              bufferResult;
     private Boolean              cache;
     private boolean              calcFoundRows;
-
     private SQLName              procedureName;
     private List<SQLExpr>        procedureArgumentList;
-
-    private boolean              lockInShareMode = false;
-
+    private boolean              lockInShareMode;
     private List<SQLCommentHint> hints;
 
     public MySqlSelectQueryBlock(){

src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlSelectParser.java

@@ -31,10 +31,7 @@ import com.alibaba.druid.sql.dialect.mysql.ast.expr.MySqlOutFileExpr;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlSelectQueryBlock;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlUpdateStatement;
 import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlUpdateTableSource;
-import com.alibaba.druid.sql.parser.ParserException;
-import com.alibaba.druid.sql.parser.SQLExprParser;
-import com.alibaba.druid.sql.parser.SQLSelectParser;
-import com.alibaba.druid.sql.parser.Token;
+import com.alibaba.druid.sql.parser.*;
 import com.alibaba.druid.util.FnvHash;
 
 import java.util.List;
@@ -48,6 +45,10 @@ public class MySqlSelectParser extends SQLSelectParser {
         super(exprParser);
     }
 
+    public MySqlSelectParser(SQLExprParser exprParser, SQLSelectListCache selectListCache){
+        super(exprParser, selectListCache);
+    }
+
     public MySqlSelectParser(String sql){
         this(new MySqlExprParser(sql));
     }
@@ -93,6 +94,12 @@ public class MySqlSelectParser extends SQLSelectParser {
             queryBlock.addBeforeComment(lexer.readAndResetComments());
         }
 
+        if (lexer.token() == Token.SELECT) {
+            if (selectListCache != null) {
+                selectListCache.match(lexer, queryBlock);
+            }
+        }
+
         if (lexer.token() == Token.SELECT) {
             lexer.nextToken();
 

src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlStatementParser.java

@@ -108,7 +108,7 @@ public class MySqlStatementParser extends SQLStatementParser {
     }
 
     public SQLStatement parseSelect() {
-        MySqlSelectParser selectParser = new MySqlSelectParser(this.exprParser);
+        MySqlSelectParser selectParser = createSQLSelectParser();
 
         SQLSelect select = selectParser.select();
 
@@ -120,7 +120,7 @@ public class MySqlStatementParser extends SQLStatementParser {
     }
 
     public SQLUpdateStatement parseUpdateStatement() {
-        return new MySqlSelectParser(this.exprParser).parseUpdateStatment();
+        return new MySqlSelectParser(this.exprParser, selectListCache).parseUpdateStatment();
     }
 
     protected MySqlUpdateStatement createUpdateStatement() {
@@ -2262,8 +2262,8 @@ public class MySqlStatementParser extends SQLStatementParser {
         return insertStatement;
     }
 
-    public SQLSelectParser createSQLSelectParser() {
-        return new MySqlSelectParser(this.exprParser);
+    public MySqlSelectParser createSQLSelectParser() {
+        return new MySqlSelectParser(this.exprParser, selectListCache);
     }
 
     public SQLStatement parseSet() {

src/main/java/com/alibaba/druid/sql/dialect/mysql/visitor/MySqlOutputVisitor.java

@@ -116,62 +116,68 @@ public class MySqlOutputVisitor extends SQLASTOutputVisitor implements MySqlASTV
             printlnComments(x.getBeforeCommentsDirect());
         }
 
-        print0(ucase ? "SELECT " : "select ");
+        String cachedSelectList = x.getCachedSelectList();
 
-        for (int i = 0, size = x.getHintsSize(); i < size; ++i) {
-            SQLCommentHint hint = x.getHints().get(i);
-            hint.accept(this);
-            print(' ');
-        }
+        if (cachedSelectList != null) {
+            print0(cachedSelectList);
+        } else {
+            print0(ucase ? "SELECT " : "select ");
 
-        final int distionOption = x.getDistionOption();
-        if (SQLSetQuantifier.ALL == distionOption) {
-            print0(ucase ? "ALL " : "all ");
-        } else if (SQLSetQuantifier.DISTINCT == distionOption) {
-            print0(ucase ? "DISTINCT " : "distinct ");
-        } else if (SQLSetQuantifier.DISTINCTROW == distionOption) {
-            print0(ucase ? "DISTINCTROW " : "distinctrow ");
-        }
-
-        if (x.isHignPriority()) {
-            print0(ucase ? "HIGH_PRIORITY " : "high_priority ");
-        }
-
-        if (x.isStraightJoin()) {
-            print0(ucase ? "STRAIGHT_JOIN " : "straight_join ");
-        }
-
-        if (x.isSmallResult()) {
-            print0(ucase ? "SQL_SMALL_RESULT " : "sql_small_result ");
-        }
-
-        if (x.isBigResult()) {
-            print0(ucase ? "SQL_BIG_RESULT " : "sql_big_result ");
-        }
-
-        if (x.isBufferResult()) {
-            print0(ucase ? "SQL_BUFFER_RESULT " : "sql_buffer_result ");
-        }
-
-        if (x.getCache() != null) {
-            if (x.getCache().booleanValue()) {
-                print0(ucase ? "SQL_CACHE " : "sql_cache ");
-            } else {
-                print0(ucase ? "SQL_NO_CACHE " : "sql_no_cache ");
+            for (int i = 0, size = x.getHintsSize(); i < size; ++i) {
+                SQLCommentHint hint = x.getHints().get(i);
+                hint.accept(this);
+                print(' ');
             }
-        }
 
-        if (x.isCalcFoundRows()) {
-            print0(ucase ? "SQL_CALC_FOUND_ROWS " : "sql_calc_found_rows ");
-        }
+            final int distionOption = x.getDistionOption();
+            if (SQLSetQuantifier.ALL == distionOption) {
+                print0(ucase ? "ALL " : "all ");
+            } else if (SQLSetQuantifier.DISTINCT == distionOption) {
+                print0(ucase ? "DISTINCT " : "distinct ");
+            } else if (SQLSetQuantifier.DISTINCTROW == distionOption) {
+                print0(ucase ? "DISTINCTROW " : "distinctrow ");
+            }
 
-        printSelectList(x.getSelectList());
+            if (x.isHignPriority()) {
+                print0(ucase ? "HIGH_PRIORITY " : "high_priority ");
+            }
 
-        SQLExprTableSource into = x.getInto();
-        if (into != null) {
-            println();
-            print0(ucase ? "INTO " : "into ");
-            printTableSource(into);
+            if (x.isStraightJoin()) {
+                print0(ucase ? "STRAIGHT_JOIN " : "straight_join ");
+            }
+
+            if (x.isSmallResult()) {
+                print0(ucase ? "SQL_SMALL_RESULT " : "sql_small_result ");
+            }
+
+            if (x.isBigResult()) {
+                print0(ucase ? "SQL_BIG_RESULT " : "sql_big_result ");
+            }
+
+            if (x.isBufferResult()) {
+                print0(ucase ? "SQL_BUFFER_RESULT " : "sql_buffer_result ");
+            }
+
+            if (x.getCache() != null) {
+                if (x.getCache().booleanValue()) {
+                    print0(ucase ? "SQL_CACHE " : "sql_cache ");
+                } else {
+                    print0(ucase ? "SQL_NO_CACHE " : "sql_no_cache ");
+                }
+            }
+
+            if (x.isCalcFoundRows()) {
+                print0(ucase ? "SQL_CALC_FOUND_ROWS " : "sql_calc_found_rows ");
+            }
+
+            printSelectList(x.getSelectList());
+
+            SQLExprTableSource into = x.getInto();
+            if (into != null) {
+                println();
+                print0(ucase ? "INTO " : "into ");
+                printTableSource(into);
+            }
         }
 
         SQLTableSource from = x.getFrom();

src/main/java/com/alibaba/druid/sql/dialect/odps/parser/OdpsSelectParser.java

@@ -28,6 +28,7 @@ import com.alibaba.druid.sql.dialect.odps.ast.OdpsLateralViewTableSource;
 import com.alibaba.druid.sql.dialect.odps.ast.OdpsSelectQueryBlock;
 import com.alibaba.druid.sql.dialect.odps.ast.OdpsValuesTableSource;
 import com.alibaba.druid.sql.parser.SQLExprParser;
+import com.alibaba.druid.sql.parser.SQLSelectListCache;
 import com.alibaba.druid.sql.parser.SQLSelectParser;
 import com.alibaba.druid.sql.parser.Token;
 
@@ -37,6 +38,12 @@ public class OdpsSelectParser extends SQLSelectParser {
         this.exprParser = exprParser;
     }
 
+    public OdpsSelectParser(SQLExprParser exprParser, SQLSelectListCache selectListCache){
+        super(exprParser.getLexer());
+        this.exprParser = exprParser;
+        this.selectListCache = selectListCache;
+    }
+
     @Override
     public SQLSelectQuery query() {
         if (lexer.token() == Token.LPAREN) {

src/main/java/com/alibaba/druid/sql/dialect/odps/parser/OdpsStatementParser.java

@@ -266,7 +266,7 @@ public class OdpsStatementParser extends SQLStatementParser {
     }
 
     public SQLSelectParser createSQLSelectParser() {
-        return new OdpsSelectParser(this.exprParser);
+        return new OdpsSelectParser(this.exprParser, selectListCache);
     }
 
     public OdpsInsert parseOdpsInsert() {

src/main/java/com/alibaba/druid/sql/dialect/oracle/parser/OracleSelectParser.java

@@ -47,10 +47,7 @@ import com.alibaba.druid.sql.dialect.oracle.ast.stmt.OracleSelectSubqueryTableSo
 import com.alibaba.druid.sql.dialect.oracle.ast.stmt.OracleSelectTableReference;
 import com.alibaba.druid.sql.dialect.oracle.ast.stmt.OracleSelectTableSource;
 import com.alibaba.druid.sql.dialect.oracle.ast.stmt.OracleSelectUnPivot;
-import com.alibaba.druid.sql.parser.ParserException;
-import com.alibaba.druid.sql.parser.SQLExprParser;
-import com.alibaba.druid.sql.parser.SQLSelectParser;
-import com.alibaba.druid.sql.parser.Token;
+import com.alibaba.druid.sql.parser.*;
 
 public class OracleSelectParser extends SQLSelectParser {
 
@@ -62,6 +59,10 @@ public class OracleSelectParser extends SQLSelectParser {
         super(exprParser);
     }
 
+    public OracleSelectParser(SQLExprParser exprParser, SQLSelectListCache selectListCache){
+        super(exprParser, selectListCache);
+    }
+
     public SQLSelect select() {
         SQLSelect select = new SQLSelect();
 

src/main/java/com/alibaba/druid/sql/dialect/oracle/parser/OracleStatementParser.java

@@ -1692,7 +1692,7 @@ public class OracleStatementParser extends SQLStatementParser {
     }
 
     public OracleSelectParser createSQLSelectParser() {
-        return new OracleSelectParser(this.exprParser);
+        return new OracleSelectParser(this.exprParser, selectListCache);
     }
 
     public OracleStatement parseInsert() {

src/main/java/com/alibaba/druid/sql/dialect/postgresql/parser/PGSQLStatementParser.java

@@ -60,7 +60,7 @@ public class PGSQLStatementParser extends SQLStatementParser {
     }
 
     public PGSelectParser createSQLSelectParser() {
-        return new PGSelectParser(this.exprParser);
+        return new PGSelectParser(this.exprParser, selectListCache);
     }
 
     public SQLUpdateStatement parseUpdateStatement() {

src/main/java/com/alibaba/druid/sql/dialect/postgresql/parser/PGSelectParser.java

@@ -30,10 +30,7 @@ import com.alibaba.druid.sql.dialect.postgresql.ast.stmt.PGFunctionTableSource;
 import com.alibaba.druid.sql.dialect.postgresql.ast.stmt.PGSelectQueryBlock;
 import com.alibaba.druid.sql.dialect.postgresql.ast.stmt.PGSelectQueryBlock.IntoOption;
 import com.alibaba.druid.sql.dialect.postgresql.ast.stmt.PGValuesQuery;
-import com.alibaba.druid.sql.parser.ParserException;
-import com.alibaba.druid.sql.parser.SQLExprParser;
-import com.alibaba.druid.sql.parser.SQLSelectParser;
-import com.alibaba.druid.sql.parser.Token;
+import com.alibaba.druid.sql.parser.*;
 
 public class PGSelectParser extends SQLSelectParser {
 
@@ -41,6 +38,10 @@ public class PGSelectParser extends SQLSelectParser {
         super(exprParser);
     }
 
+    public PGSelectParser(SQLExprParser exprParser, SQLSelectListCache selectListCache){
+        super(exprParser, selectListCache);
+    }
+
     public PGSelectParser(String sql){
         this(new PGExprParser(sql));
     }

src/main/java/com/alibaba/druid/sql/dialect/sqlserver/parser/SQLServerSelectParser.java

@@ -20,10 +20,7 @@ import com.alibaba.druid.sql.ast.SQLSetQuantifier;
 import com.alibaba.druid.sql.ast.statement.*;
 import com.alibaba.druid.sql.dialect.sqlserver.ast.SQLServerSelectQueryBlock;
 import com.alibaba.druid.sql.dialect.sqlserver.ast.SQLServerTop;
-import com.alibaba.druid.sql.parser.ParserException;
-import com.alibaba.druid.sql.parser.SQLExprParser;
-import com.alibaba.druid.sql.parser.SQLSelectParser;
-import com.alibaba.druid.sql.parser.Token;
+import com.alibaba.druid.sql.parser.*;
 
 public class SQLServerSelectParser extends SQLSelectParser {
 
@@ -35,6 +32,10 @@ public class SQLServerSelectParser extends SQLSelectParser {
         super(exprParser);
     }
 
+    public SQLServerSelectParser(SQLExprParser exprParser, SQLSelectListCache selectListCache){
+        super(exprParser, selectListCache);
+    }
+
     public SQLSelect select() {
         SQLSelect select = new SQLSelect();
 

src/main/java/com/alibaba/druid/sql/dialect/sqlserver/parser/SQLServerStatementParser.java

@@ -51,7 +51,7 @@ public class SQLServerStatementParser extends SQLStatementParser {
     }
 
     public SQLSelectParser createSQLSelectParser() {
-        return new SQLServerSelectParser(this.exprParser);
+        return new SQLServerSelectParser(this.exprParser, selectListCache);
     }
 
     public SQLServerStatementParser(Lexer lexer){

src/main/java/com/alibaba/druid/sql/parser/SQLParserUtils.java

@@ -15,16 +15,20 @@
  */
 package com.alibaba.druid.sql.parser;
 
+import com.alibaba.druid.sql.ast.statement.SQLSelectQueryBlock;
+import com.alibaba.druid.sql.dialect.db2.ast.stmt.DB2SelectQueryBlock;
 import com.alibaba.druid.sql.dialect.db2.parser.DB2ExprParser;
 import com.alibaba.druid.sql.dialect.db2.parser.DB2Lexer;
 import com.alibaba.druid.sql.dialect.db2.parser.DB2StatementParser;
 import com.alibaba.druid.sql.dialect.h2.parser.H2StatementParser;
+import com.alibaba.druid.sql.dialect.mysql.ast.statement.MySqlSelectQueryBlock;
 import com.alibaba.druid.sql.dialect.mysql.parser.MySqlExprParser;
 import com.alibaba.druid.sql.dialect.mysql.parser.MySqlLexer;
 import com.alibaba.druid.sql.dialect.mysql.parser.MySqlStatementParser;
 import com.alibaba.druid.sql.dialect.odps.parser.OdpsExprParser;
 import com.alibaba.druid.sql.dialect.odps.parser.OdpsLexer;
 import com.alibaba.druid.sql.dialect.odps.parser.OdpsStatementParser;
+import com.alibaba.druid.sql.dialect.oracle.ast.stmt.OracleSelectQueryBlock;
 import com.alibaba.druid.sql.dialect.oracle.parser.OracleExprParser;
 import com.alibaba.druid.sql.dialect.oracle.parser.OracleLexer;
 import com.alibaba.druid.sql.dialect.oracle.parser.OracleStatementParser;
@@ -173,4 +177,32 @@ public class SQLParserUtils {
 
         return new Lexer(sql);
     }
+
+    public static SQLSelectQueryBlock createSelectQueryBlock(String dbType) {
+        if (JdbcConstants.MYSQL.equals(dbType)) {
+            return new MySqlSelectQueryBlock();
+        }
+
+        if (JdbcConstants.ORACLE.equals(dbType)) {
+            return new OracleSelectQueryBlock();
+        }
+
+        if (JdbcConstants.DB2.equals(dbType)) {
+            return new DB2SelectQueryBlock();
+        }
+
+        if (JdbcConstants.POSTGRESQL.equals(dbType)) {
+            return new DB2SelectQueryBlock();
+        }
+
+        if (JdbcConstants.ODPS.equals(dbType)) {
+            return new DB2SelectQueryBlock();
+        }
+
+        if (JdbcConstants.SQL_SERVER.equals(dbType)) {
+            return new DB2SelectQueryBlock();
+        }
+
+        return new SQLSelectQueryBlock();
+     }
 }

src/main/java/com/alibaba/druid/sql/parser/SQLSelectListCache.java

@@ -0,0 +1,78 @@
+/*
+ * Copyright 1999-2017 Alibaba Group Holding Ltd.
+ *
+ * Licensed 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 com.alibaba.druid.sql.parser;
+
+import com.alibaba.druid.sql.SQLUtils;
+import com.alibaba.druid.sql.ast.statement.SQLSelectQueryBlock;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+public class SQLSelectListCache {
+    private final String dbType;
+    private List<String> sqlCache = new ArrayList<String>();
+    private List<SQLSelectQueryBlock> queryBlockCache = new ArrayList<SQLSelectQueryBlock>();
+    private List<String> printSqlList = new ArrayList<String>();
+
+    public SQLSelectListCache(String dbType) {
+        this.dbType = dbType;
+    }
+
+    public void add(String select) {
+        if (select == null || select.length() == 0) {
+            return;
+        }
+
+        SQLSelectParser selectParser = SQLParserUtils.createSQLStatementParser(select, dbType)
+                                                     .createSQLSelectParser();
+        SQLSelectQueryBlock queryBlock = SQLParserUtils.createSelectQueryBlock(dbType);
+        selectParser.accept(Token.SELECT);
+
+        selectParser.parseSelectList(queryBlock);
+
+        selectParser.accept(Token.FROM);
+        selectParser.accept(Token.EOF);
+
+        sqlCache.add(select.substring(6));
+        queryBlockCache.add(queryBlock);
+        printSqlList.add(queryBlock.toString());
+    }
+
+    public boolean match(Lexer lexer, SQLSelectQueryBlock queryBlock) {
+        if (lexer.token != Token.SELECT) {
+            return false;
+        }
+
+        int pos = lexer.pos;
+        String text = lexer.text;
+
+        for (int i = 0; i < sqlCache.size(); i++) {
+            String block = sqlCache.get(i);
+            if (text.startsWith(block, pos)) {
+                //SQLSelectQueryBlock queryBlockCached = queryBlockCache.get(i);
+                // queryBlockCached.cloneSelectListTo(queryBlock);
+                String printSql = printSqlList.get(i);
+                queryBlock.setCachedSelectList(printSql);
+
+                int len = pos + block.length();
+                lexer.reset(len, text.charAt(len), Token.FROM);
+                return true;
+            }
+        }
+        return false;
+    }
+}

src/main/java/com/alibaba/druid/sql/parser/SQLSelectParser.java

@@ -27,7 +27,8 @@ import com.alibaba.druid.util.FnvHash;
 import com.alibaba.druid.util.JdbcConstants;
 
 public class SQLSelectParser extends SQLParser {
-    protected SQLExprParser exprParser;
+    protected SQLExprParser      exprParser;
+    protected SQLSelectListCache selectListCache;
 
     public SQLSelectParser(String sql){
         super(sql);
@@ -38,8 +39,13 @@ public class SQLSelectParser extends SQLParser {
     }
 
     public SQLSelectParser(SQLExprParser exprParser){
+        this(exprParser, null);
+    }
+
+    public SQLSelectParser(SQLExprParser exprParser, SQLSelectListCache selectListCache){
         super(exprParser.getLexer(), exprParser.getDbType());
         this.exprParser = exprParser;
+        this.selectListCache = selectListCache;
     }
 
     public SQLSelect select() {

src/main/java/com/alibaba/druid/sql/parser/SQLStatementParser.java

@@ -29,9 +29,10 @@ import com.alibaba.druid.util.JdbcConstants;
 
 public class SQLStatementParser extends SQLParser {
 
-    protected SQLExprParser exprParser;
-    protected boolean       parseCompleteValues = true;
-    protected int           parseValuesSize     = 3;
+    protected SQLExprParser      exprParser;
+    protected boolean            parseCompleteValues = true;
+    protected int                parseValuesSize     = 3;
+    protected SQLSelectListCache selectListCache     = null;
 
     public SQLStatementParser(String sql){
         this(sql, null);
@@ -83,6 +84,20 @@ public class SQLStatementParser extends SQLParser {
     }
 
     public void parseStatementList(List<SQLStatement> statementList, int max, SQLObject parent) {
+        if ("select @@session.tx_read_only".equals(lexer.text)
+                && lexer.token == Token.SELECT) {
+            SQLSelect select = new SQLSelect();
+            MySqlSelectQueryBlock queryBlock = new MySqlSelectQueryBlock();
+            queryBlock.addSelectItem(new SQLPropertyExpr(new SQLVariantRefExpr("@@session"), "tx_read_only"));
+            select.setQuery(queryBlock);
+
+            SQLSelectStatement stmt = new SQLSelectStatement(select);
+            statementList.add(stmt);
+
+            lexer.reset(29, '\u001A', Token.EOF);
+            return;
+        }
+
         for (;;) {
             if (max != -1) {
                 if (statementList.size() >= max) {
@@ -2150,7 +2165,7 @@ public class SQLStatementParser extends SQLParser {
     }
 
     public SQLSelectParser createSQLSelectParser() {
-        return new SQLSelectParser(this.exprParser);
+        return new SQLSelectParser(this.exprParser, selectListCache);
     }
 
     public SQLUpdateStatement parseUpdateStatement() {
@@ -2959,4 +2974,12 @@ public class SQLStatementParser extends SQLParser {
             }
         }
     }
+
+    public SQLSelectListCache getSelectListCache() {
+        return selectListCache;
+    }
+
+    public void setSelectListCache(SQLSelectListCache selectListCache) {
+        this.selectListCache = selectListCache;
+    }
 }