change

src/connector/jdbc/src/main/java/com/taosdata/jdbc/AbstractDatabaseMetaData.java

@@ -497,12 +497,12 @@ public abstract class AbstractDatabaseMetaData implements DatabaseMetaData {
 
     public ResultSet getProcedures(String catalog, String schemaPattern, String procedureNamePattern)
             throws SQLException {
-        throw new SQLException(TSDBConstants.UNSUPPORT_METHOD_EXCEPTIONZ_MSG);
+        return null;
     }
 
     public ResultSet getProcedureColumns(String catalog, String schemaPattern, String procedureNamePattern,
                                          String columnNamePattern) throws SQLException {
-        throw new SQLException(TSDBConstants.UNSUPPORT_METHOD_EXCEPTIONZ_MSG);
+        return null;
     }
 
     public abstract ResultSet getTables(String catalog, String schemaPattern, String tableNamePattern, String[] types)

src/connector/jdbc/src/main/java/com/taosdata/jdbc/TSDBDatabaseMetaData.java

@@ -20,13 +20,11 @@ import java.util.List;
 
 public class TSDBDatabaseMetaData implements java.sql.DatabaseMetaData {
 
-    private String dbProductName = null;
-    private String url = null;
-    private String userName = null;
-    private Connection conn = null;
+    private String url;
+    private String userName;
+    private Connection conn;
 
-    public TSDBDatabaseMetaData(String dbProductName, String url, String userName) {
-        this.dbProductName = dbProductName;
+    public TSDBDatabaseMetaData(String url, String userName) {
         this.url = url;
         this.userName = userName;
     }
@@ -116,7 +114,9 @@ public class TSDBDatabaseMetaData implements java.sql.DatabaseMetaData {
         return false;
     }
 
+
     public boolean supportsMixedCaseIdentifiers() throws SQLException {
+        //像database、table这些对象的标识符，在存储时是否采用大小写混合的模式
         return false;
     }
 
@@ -125,7 +125,7 @@ public class TSDBDatabaseMetaData implements java.sql.DatabaseMetaData {
     }
 
     public boolean storesLowerCaseIdentifiers() throws SQLException {
-        return false;
+        return true;
     }
 
     public boolean storesMixedCaseIdentifiers() throws SQLException {
@@ -133,6 +133,7 @@ public class TSDBDatabaseMetaData implements java.sql.DatabaseMetaData {
     }
 
     public boolean supportsMixedCaseQuotedIdentifiers() throws SQLException {
+        //像database、table这些对象的标识符，在存储时是否采用大小写混合、并带引号的模式
         return false;
     }
 
@@ -193,10 +194,12 @@ public class TSDBDatabaseMetaData implements java.sql.DatabaseMetaData {
     }
 
     public boolean nullPlusNonNullIsNull() throws SQLException {
+        // null + non-null != null
         return false;
     }
 
     public boolean supportsConvert() throws SQLException {
+        // 是否支持转换函数convert
         return false;
     }
 
@@ -221,7 +224,7 @@ public class TSDBDatabaseMetaData implements java.sql.DatabaseMetaData {
     }
 
     public boolean supportsGroupBy() throws SQLException {
-        return false;
+        return true;
     }
 
     public boolean supportsGroupByUnrelated() throws SQLException {
@@ -493,7 +496,7 @@ public class TSDBDatabaseMetaData implements java.sql.DatabaseMetaData {
     }
 
     public int getDefaultTransactionIsolation() throws SQLException {
-        return 0;
+        return Connection.TRANSACTION_NONE;
     }
 
     public boolean supportsTransactions() throws SQLException {
@@ -501,6 +504,8 @@ public class TSDBDatabaseMetaData implements java.sql.DatabaseMetaData {
     }
 
     public boolean supportsTransactionIsolationLevel(int level) throws SQLException {
+        if (level == Connection.TRANSACTION_NONE)
+            return true;
         return false;
     }
 
@@ -522,28 +527,27 @@ public class TSDBDatabaseMetaData implements java.sql.DatabaseMetaData {
 
     public ResultSet getProcedures(String catalog, String schemaPattern, String procedureNamePattern)
             throws SQLException {
-        throw new SQLException(TSDBConstants.UNSUPPORT_METHOD_EXCEPTIONZ_MSG);
+        return null;
     }
 
     public ResultSet getProcedureColumns(String catalog, String schemaPattern, String procedureNamePattern,
                                          String columnNamePattern) throws SQLException {
-        throw new SQLException(TSDBConstants.UNSUPPORT_METHOD_EXCEPTIONZ_MSG);
+        return null;
     }
 
-    public ResultSet getTables(String catalog, String schemaPattern, String tableNamePattern, String[] types)
-            throws SQLException {
-        Statement stmt = null;
-        if (null != conn && !conn.isClosed()) {
-            stmt = conn.createStatement();
-            if (catalog == null || catalog.length() < 1) {
-                catalog = conn.getCatalog();
-            }
+    public ResultSet getTables(String catalog, String schemaPattern, String tableNamePattern, String[] types) throws SQLException {
+        if (conn == null || conn.isClosed()) {
+            throw new SQLException(TSDBConstants.FixErrMsg(TSDBConstants.JNI_CONNECTION_NULL));
+        }
+
+        try (Statement stmt = conn.createStatement()) {
+            if (catalog == null || catalog.isEmpty())
+                return null;
+
             stmt.executeUpdate("use " + catalog);
             ResultSet resultSet0 = stmt.executeQuery("show tables");
             GetTablesResultSet getTablesResultSet = new GetTablesResultSet(resultSet0, catalog, schemaPattern, tableNamePattern, types);
             return getTablesResultSet;
-        } else {
-            throw new SQLException(TSDBConstants.FixErrMsg(TSDBConstants.JNI_CONNECTION_NULL));
         }
     }
 
@@ -552,14 +556,12 @@ public class TSDBDatabaseMetaData implements java.sql.DatabaseMetaData {
     }
 
     public ResultSet getCatalogs() throws SQLException {
+        if (conn == null || conn.isClosed())
+            throw new SQLException(TSDBConstants.FixErrMsg(TSDBConstants.JNI_CONNECTION_NULL));
 
-        if (conn != null && !conn.isClosed()) {
-            Statement stmt = conn.createStatement();
-            ResultSet resultSet0 = stmt.executeQuery("show databases");
-            CatalogResultSet resultSet = new CatalogResultSet(resultSet0);
-            return resultSet;
-        } else {
-            return getEmptyResultSet();
+        try (Statement stmt = conn.createStatement()) {
+            ResultSet rs = stmt.executeQuery("show databases");
+            return new CatalogResultSet(rs);
         }
     }
 
@@ -567,7 +569,7 @@ public class TSDBDatabaseMetaData implements java.sql.DatabaseMetaData {
         DatabaseMetaDataResultSet resultSet = new DatabaseMetaDataResultSet();
 
         // set up ColumnMetaDataList
-        List<ColumnMetaData> columnMetaDataList = new ArrayList<ColumnMetaData>(1);
+        List<ColumnMetaData> columnMetaDataList = new ArrayList<>(1);
         ColumnMetaData colMetaData = new ColumnMetaData();
         colMetaData.setColIndex(0);
         colMetaData.setColName("TABLE_TYPE");
@@ -576,7 +578,7 @@ public class TSDBDatabaseMetaData implements java.sql.DatabaseMetaData {
         columnMetaDataList.add(colMetaData);
 
         // set up rowDataList
-        List<TSDBResultSetRowData> rowDataList = new ArrayList<TSDBResultSetRowData>(2);
+        List<TSDBResultSetRowData> rowDataList = new ArrayList<>(2);
         TSDBResultSetRowData rowData = new TSDBResultSetRowData();
         rowData.setString(0, "TABLE");
         rowDataList.add(rowData);
@@ -596,11 +598,10 @@ public class TSDBDatabaseMetaData implements java.sql.DatabaseMetaData {
         Statement stmt = null;
         if (null != conn && !conn.isClosed()) {
             stmt = conn.createStatement();
-            if (catalog == null || catalog.length() < 1) {
-                catalog = conn.getCatalog();
-            }
-            stmt.executeUpdate("use " + catalog);
+            if (catalog == null || catalog.isEmpty())
+                return null;
 
+            stmt.executeUpdate("use " + catalog);
             DatabaseMetaDataResultSet resultSet = new DatabaseMetaDataResultSet();
             // set up ColumnMetaDataList
             List<ColumnMetaData> columnMetaDataList = new ArrayList<>(24);
@@ -856,7 +857,7 @@ public class TSDBDatabaseMetaData implements java.sql.DatabaseMetaData {
     }
 
     public Connection getConnection() throws SQLException {
-        return null;
+        return this.conn;
     }
 
     public boolean supportsSavepoints() throws SQLException {
@@ -889,11 +890,13 @@ public class TSDBDatabaseMetaData implements java.sql.DatabaseMetaData {
     }
 
     public boolean supportsResultSetHoldability(int holdability) throws SQLException {
+        if (holdability == ResultSet.HOLD_CURSORS_OVER_COMMIT)
+            return true;
         return false;
     }
 
     public int getResultSetHoldability() throws SQLException {
-        return 0;
+        return ResultSet.HOLD_CURSORS_OVER_COMMIT;
     }
 
     public int getDatabaseMajorVersion() throws SQLException {

src/connector/jdbc/src/main/java/com/taosdata/jdbc/TSDBDriver.java

@@ -214,7 +214,7 @@ public class TSDBDriver extends AbstractTaosDriver {
             urlProps.setProperty(TSDBDriver.PROPERTY_KEY_HOST, url);
         }
         
-        this.dbMetaData = new TSDBDatabaseMetaData(dbProductName, urlForMeta, urlProps.getProperty(TSDBDriver.PROPERTY_KEY_USER));
+        this.dbMetaData = new TSDBDatabaseMetaData(urlForMeta, urlProps.getProperty(TSDBDriver.PROPERTY_KEY_USER));
         return urlProps;
     }
 

src/connector/jdbc/src/main/java/com/taosdata/jdbc/rs/RestfulDatabaseMetaData.java

@@ -8,7 +8,6 @@ import java.util.List;
 
 public class RestfulDatabaseMetaData extends AbstractDatabaseMetaData {
 
-
     private final String url;
     private final String userName;
     private final Connection connection;

src/connector/jdbc/src/test/java/com/taosdata/jdbc/DatabaseMetaDataTest.java

@@ -168,6 +168,7 @@ public class DatabaseMetaDataTest {
         try {
             databaseMetaData.getProcedures("", "", "");
         } catch (Exception e) {
+
         }
         try {
             databaseMetaData.getProcedureColumns("", "", "", "");
@@ -176,6 +177,7 @@ public class DatabaseMetaDataTest {
         try {
             databaseMetaData.getTables("", "", "", new String[]{""});
         } catch (Exception e) {
+
         }
         databaseMetaData.getSchemas();
         databaseMetaData.getCatalogs();

src/connector/jdbc/src/test/java/com/taosdata/jdbc/cases/MultiThreadsWithSameStatmentTest.java

+package com.taosdata.jdbc.cases;
+
+import org.junit.After;
+import org.junit.AfterClass;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.sql.*;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.IntStream;
+
+public class MultiThreadsWithSameStatmentTest {
+    private Connection conn;
+    private Statement stmt;
+
+    @Before
+    public void before() {
+        try {
+            Class.forName("com.taosdata.jdbc.TSDBDriver");
+            conn = DriverManager.getConnection("jdbc:TAOS://localhost:6030/?user=root&password=taosdata");
+            stmt = conn.createStatement();
+            stmt.execute("create database if not exists jdbctest");
+            stmt.executeUpdate("create table jdbctest.weather (ts timestamp, f1 int)");
+
+        } catch (ClassNotFoundException | SQLException e) {
+            e.printStackTrace();
+        }
+    }
+
+    @Test
+    public void test() {
+        Thread t1 = new Thread(() -> {
+            try {
+                ResultSet resultSet = stmt.executeQuery("select * from log.");
+                sleep(5000);
+                while (resultSet.next()) {
+                    ResultSetMetaData metaData = resultSet.getMetaData();
+                    for (int i = 1; i <= metaData.getColumnCount(); i++) {
+                        System.out.print(metaData.getColumnLabel(i) + ": " + resultSet.getString(i));
+                    }
+                    System.out.println();
+                }
+            } catch (SQLException e) {
+                e.printStackTrace();
+            }
+        });
+
+        Thread t2 = new Thread(() -> {
+            try {
+                stmt.executeUpdate("insert into jdbctest.weather values(now,1)");
+            } catch (SQLException e) {
+                e.printStackTrace();
+            }
+        });
+        t1.start();
+        sleep(1000);
+        t2.start();
+    }
+
+    private void sleep(long mills) {
+        try {
+            TimeUnit.MILLISECONDS.sleep(mills);
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+        }
+    }
+
+    @After
+    public void after() {
+        try {
+            if (stmt != null)
+                stmt.close();
+            if (conn != null)
+                conn.close();
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+    }
+}