1. What should be paid attention to when the version before TDengine2.0 is upgraded to version 2.0 and above? Do do do

Version 2.0 is a complete refactor. configuration files and data files are incompatible. Before the upgrade, perform the following operations:

To delete the configuration file, run sudo rm -rf /etc/taos/taos.cfg

To delete the log file, run sudo rm -rf /var/log/taos/

If the data is no longer needed, delete the data files and run sudo rm -rf /var/lib/taos/ to install the latest stable TDengine

If the data needs to be migrated or the data file is damaged, please contact taOS official technical support team ([email protected]) for assistance

2. What should I do if the JDBCDriver on Windows fails to find the dynamic link library?

See the tech blog on this issue

3. The more DNodes are needed message is displayed when creating a data table

See the tech blog on the subject

4. How to generate core files when the TDengine crashes?

See the tech blog on the subject

5. “Unable to establish connection” error is encountered, what should I do?

If the client encounters a link failure, perform the following steps:

1. Check the network environment

Cloud server: Check whether TCP/UDP ports 6030-6042 are enabled for the security group of the cloud server

Local VM: Check whether the network can be pinged. Do not use localhost as the hostname

Corporate server: In a NAT network environment, be sure to check whether the server can return messages to the client

2. Ensure that the version numbers of the client and server are the same, and do not mix the open source community version and enterprise version

3. On the server, run the systemctl status taosd command to check the taOSD running status. If it is not running, start TAosd

4. Ensure that the FQDN of the server is Fully Qualified Domain Name(you can run the hostname -f command on the server to obtain the FQDN).

5. Ping the server FQDN. If no response, check your network, DNS Settings, or the system hosts file on the computer where the client resides

6. Check firewall Settings and ensure that TCP/UDP ports 6030-6042 are enabled

7. For JDBC (ODBC, Python, Go, etc.) connections on Linux, make sure libtaos.so is in /usr/local/lib/taos, LD_LIBRARY_PATH = /usr/local/lib/taos/LD_LIBRARY_PATH = /usr/local/lib/taos

8. For JDBC, ODBC, Python, Go, etc connections on Windows, make sure driver/c/taos.dll is in your system search directory (recommend taos.dll in c :\Windows\System32).

9. If the connection fault still persists, run the NC command to check whether the TCP and UDP connections on the specified port are normal. Check whether the UDP port connection works: NC-vuz {hostIP} {port} Check whether the TCP port connection on the server is normal. Nc -l {port} Check whether the TCP port connection on the client works: nc {hostIP} {port}

You can also use the embedded network connectivity detection function of taOS to verify that the connection between the server and the client is normal (including TCP and UDP) : TDengine Embedded network detection Tool Guide

Unexpected generic error in RPC or TDengine error: Unable to resolve FQDN

The Fully Qualified Domain Name (FQDN) cannot be resolved by the client or data node. For TAOS Shell or client applications, check the following:

  1. Check whether the FQDN of the connected server is correct
  2. If the DNS server is configured on the network, check whether it works properly
  3. If the DNS server is not configured on the network, check whether the FQDN is configured and the IP address is correct in the hosts file on the host where the client resides.
  4. If the network configuration is OK, you need to be able to Ping the FQDN of the connection from the client’s machine, otherwise the client will not be able to connect to the server

7. Why do I get an “Invalid SQL” error even though the syntax is correct

If you are sure the syntax is correct, before 2.0, check if the SQL statement is longer than 64K. If it exceeds, this error is also returned.

8. Is Validation queries supported?

The TDengine does not yet have a dedicated set of validation queries. However, it is recommended that you use the system monitor database “log” to do this.

9. Can I delete or update a record?

Can’t. Because the TDengine is designed for data collected from networked devices, it does not allow modification. However, the TDengine provides a data retention policy, and data records that exceed the retention period are automatically deleted.

10. How do I create a table with more than 1024 columns?

If 2.0 or later versions are used, 1024 columns are supported by default. Prior to 2.0, TDengine allowed tables with a maximum of 250 columns to be created. However, if you do exceed the limit, it is recommended to logically decompose the wide table into several smaller tables, based on the characteristics of the data.

11. What is the most efficient way to write data?

Batch insert. Each write statement can insert multiple records into a table at the same time or multiple records from multiple tables at the same time.

12. How to solve the problem that Chinese characters in nCHAR class data inserted in Windows system are parsed into garbled characters?

If you insert Chinese characters into the nCHAR class in Windows, make sure the locale is set to China (this can be set in the Control Panel), then the TAOS client in CMD should be working properly. If you are developing Java applications in an IDE, such as Eclipse or Intellij, make sure that the IDE files are encoded as GBK (which is the default Java encoding type), and then initialize the client configuration when the Connection is generated.

Class.forName("com.taosdata.jdbc.TSDBDriver");
Properties properties = new Properties();
properties.setProperty(TSDBDriver.LOCALE_KEY, "UTF-8");
Connection = DriverManager.getConnection(url, properties);
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How to compile the TDengine GO Windows driver?

See the tech blog on this issue

14. JDBC error: The excuted SQL is not a DML or a DDL?

Update the JDBC driver to the latest version

< the dependency > < groupId > com. Taosdata. JDBC < / groupId > < artifactId > taos - jdbcdriver < / artifactId > < version > 2.0.4 < / version > </dependency>Copy the code

15. How to report problems?

If the information in the FAQ does not help you and you need technical support and assistance from the TDengine technical team, please package the contents in the following two directories:

/var/log/taos
/etc/taos
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Submit the Issue on GitHub with the necessary description of the problem, the actions taken to troubleshoot the problem, the description of the problem and the approximate time.

To ensure sufficient debugging information, if the problem can be repeated, modify the /etc/taos/taos. CFG file and add a line of “debugFlag 135″(without quotation marks) at the end, restart taosd, repeat the problem, and then submit the problem. When the system runs normally, ensure that the debugFlag value is set to 131. Otherwise, a large number of logs are generated and the system efficiency is reduced.