feat: PostgreSQL resource tree list multiple databases (catalogs)

server/odc-service/src/main/java/com/oceanbase/odc/service/connection/table/TableService.java

@@ -60,6 +60,7 @@
 import com.oceanbase.odc.service.connection.model.ConnectionConfig;
 import com.oceanbase.odc.service.connection.table.model.QueryTableParams;
 import com.oceanbase.odc.service.connection.table.model.Table;
+import com.oceanbase.odc.service.connection.util.ConnectionMapper;
 import com.oceanbase.odc.service.db.DBMaterializedViewService;
 import com.oceanbase.odc.service.db.schema.DBSchemaSyncService;
 import com.oceanbase.odc.service.db.schema.syncer.DBSchemaSyncer;
@@ -130,7 +131,8 @@ public List<Table> list(@NonNull @Valid QueryTableParams params) throws SQLExcep
             return Collections.emptyList();
         }
         Database database = databaseService.detail(params.getDatabaseId());
-        ConnectionConfig dataSource = database.getDataSource();
+        ConnectionConfig dataSource = ConnectionMapper.INSTANCE.clone(database.getDataSource());
+        OBConsoleDataSourceFactory.applyPostgresCatalogForDatabase(dataSource, database.getName());
         OBConsoleDataSourceFactory factory = new OBConsoleDataSourceFactory(dataSource, true);
         List<Table> tables = new ArrayList<>();
         try (SingleConnectionDataSource ds = (SingleConnectionDataSource) factory.getDataSource();

server/odc-service/src/main/java/com/oceanbase/odc/service/db/schema/DBSchemaSyncService.java

@@ -42,6 +42,7 @@
 import com.oceanbase.odc.service.connection.ConnectionService;
 import com.oceanbase.odc.service.connection.database.model.Database;
 import com.oceanbase.odc.service.connection.model.ConnectionConfig;
+import com.oceanbase.odc.service.connection.util.ConnectionMapper;
 import com.oceanbase.odc.service.db.schema.syncer.DBSchemaSyncer;
 import com.oceanbase.odc.service.session.factory.OBConsoleDataSourceFactory;
 
@@ -85,7 +86,9 @@ public boolean sync(@NonNull Database database) throws InterruptedException, SQL
         }
         try {
             ConnectionConfig config = connectionService.getForConnectionSkipPermissionCheck(dataSourceId);
-            OBConsoleDataSourceFactory factory = new OBConsoleDataSourceFactory(config, true);
+            ConnectionConfig connectConfig = ConnectionMapper.INSTANCE.clone(config);
+            OBConsoleDataSourceFactory.applyPostgresCatalogForDatabase(connectConfig, database.getName());
+            OBConsoleDataSourceFactory factory = new OBConsoleDataSourceFactory(connectConfig, true);
             try (SingleConnectionDataSource dataSource = (SingleConnectionDataSource) factory.getDataSource();
                     Connection conn = dataSource.getConnection()) {
                 boolean success = true;

server/odc-service/src/main/java/com/oceanbase/odc/service/session/ConnectSessionService.java

@@ -294,6 +294,10 @@ public ConnectionSession create(@NotNull CreateSessionReq req) {
                 connection.setDefaultSchema(StringUtils.isNotBlank(catalogAndSchema[1])
                         ? catalogAndSchema[1]
                         : schemaName);
+            } else if (DialectType.POSTGRESQL == connection.getDialectType()
+                    || DialectType.GAUSSDB == connection.getDialectType()) {
+                // Tree node is a catalog; reconnect JDBC URL to that database (PG cannot USE mid-session).
+                OBConsoleDataSourceFactory.applyPostgresCatalogForDatabase(connection, schemaName);
             } else {
                 connection.setDefaultSchema(schemaName);
             }

server/odc-service/src/main/java/com/oceanbase/odc/service/session/factory/OBConsoleDataSourceFactory.java

@@ -221,6 +221,30 @@ public static String[] resolveSqlServerCatalogAndSchema(String catalogName, Stri
         return new String[] {null, defaultSchema};
     }
 
+    /**
+     * Bind a resource-tree database node to the PostgreSQL/GaussDB JDBC catalog.
+     * <p>
+     * PG cannot {@code USE} another database mid-connection; the catalog must be present in the JDBC
+     * URL. Tree nodes after multi-database sync are catalogs (from {@code pg_database}), so selecting
+     * node {@code wms_ftest} must reconnect to that catalog. Object metadata still lives under schemas
+     * (default {@code public}), which becomes {@code currentSchema}/{@code search_path}.
+     * </p>
+     *
+     * @param connectionConfig connection to mutate (caller should clone if shared)
+     * @param databaseName resource-tree database node name (catalog)
+     */
+    public static void applyPostgresCatalogForDatabase(ConnectionConfig connectionConfig, String databaseName) {
+        if (connectionConfig == null || StringUtils.isBlank(databaseName)) {
+            return;
+        }
+        DialectType dialectType = connectionConfig.getDialectType();
+        if (DialectType.POSTGRESQL != dialectType && DialectType.GAUSSDB != dialectType) {
+            return;
+        }
+        connectionConfig.setCatalogName(databaseName);
+        connectionConfig.setDefaultSchema(OdcConstants.POSTGRESQL_DEFAULT_SCHEMA);
+    }
+
     public static String getUsername(@NonNull ConnectionConfig connectionConfig) {
         String username = getDbUser(connectionConfig);
         if (DialectType.OB_ORACLE.equals(connectionConfig.getDialectType())) {

server/plugins/connect-plugin-gaussdb/src/main/java/com/oceanbase/odc/plugin/connect/gaussdb/GaussDBSessionExtension.java

@@ -71,6 +71,12 @@ public String getKillSessionSql(@NonNull String connectionId) {
 
     @Override
     public void switchSchema(Connection connection, String schemaName) throws SQLException {
+        // Align with PostgresSessionExtension: tree nodes are catalogs after multi-DB sync.
+        String currentDatabase = JdbcOperationsUtil.getJdbcOperations(connection)
+                .queryForObject("SELECT current_database()", String.class);
+        if (schemaName != null && schemaName.equals(currentDatabase)) {
+            schemaName = "public";
+        }
         String sql = "SET search_path TO " + quoteIdentifier(schemaName);
         JdbcOperationsUtil.getJdbcOperations(connection).execute(sql);
     }

server/plugins/connect-plugin-postgres/src/main/java/com/oceanbase/odc/plugin/connect/postgres/PostgresSessionExtension.java

@@ -58,6 +58,11 @@ public class PostgresSessionExtension extends OBMySQLSessionExtension {
      */
     @Override
     public void switchSchema(Connection connection, String schemaName) throws SQLException {
+        // Resource-tree nodes are catalogs; map catalog name to default schema public.
+        String currentDatabase = getCurrentDatabase(connection);
+        if (Objects.equals(schemaName, currentDatabase)) {
+            schemaName = "public";
+        }
         String currentSchema = getCurrentSchema(connection);
         if (Objects.equals(currentSchema, schemaName)) {
             return;