Configuration Parameters

Configuration File on Server Side

On the server side, the actual service of TDengine is provided by an executable taosd whose parameters can be configured in file taos.cfg to meet the requirements of different use cases. The default location of taos.cfg is /etc/taos, but can be changed by using -c parameter on the CLI of taosd. For example, the configuration file can be put under /home/user and used like below

taosd -c /home/user

Parameter -C can be used on the CLI of taosd to show its configuration, like below:

taosd -C

Configuration File on Client Side

TDengine CLI taos is the tool for users to interact with TDengine. It can share same configuration file as taosd or use a separate configuration file. When launching taos, parameter -c can be used to specify the location where its configuration file is. For example taos -c /home/cfg means /home/cfg/taos.cfg will be used. If -c is not used, the default location of the configuration file is /etc/taos. For more details please use taos --help to get.

taos -C

taos --dump-config

Configuration Parameters

note

The parameters described in this document by the effect that they have on the system.

note

taosd needs to be restarted for the parameters changed in the configuration file to take effect.

Connection Parameters

firstEp

secondEp

fqdn

serverPort

note

• Ensure that your firewall rules do not block TCP port 6042 on any host in the cluster. Below table describes the ports used by TDengine in details.

maxShellConns

Monitoring Parameters

monitor

monitorFqdn

monitorPort

monitorInterval

telemetryReporting

Query Parameters

queryPolicy

2: Run subtasks without scan operators on qnodes and subtasks with scan operators on vnodes.

3: Only run scan operators on vnodes; run all other operators on qnodes. |

querySmaOptimize

0: Disable SMA indexing and perform all queries on non-indexed data.

1: Enable SMA indexing and perform queries from suitable statements on precomputation results.|

countAlwaysReturnValue

maxNumOfDistinctRes

keepColumnName

Locale Parameters

timezone

info

To handle the data insertion and data query from multiple timezones, Unix Timestamp is used and stored in TDengine. The timestamp generated from any timezones at same time is same in Unix timestamp. Note that Unix timestamps are converted and recorded on the client side. To make sure the time on client side can be converted to Unix timestamp correctly, the timezone must be set properly.

On Linux/macOS, TDengine clients automatically obtain timezone from the host. Alternatively, the timezone can be configured explicitly in configuration file taos.cfg like below. For example:

timezone UTC-8
timezone GMT-8
timezone Asia/Shanghai

The above examples are all proper configuration for the timezone of UTC+8. On Windows system, however, timezone Asia/Shanghai is not supported, it must be set as timezone UTC-8.

The setting for timezone impacts strings that are not in Unix timestamp format and keywords or functions related to date/time. For example:

SELECT count(*) FROM table_name WHERE TS<'2019-04-11 12:01:08';

If the timezone is UTC+8, the above SQL statement is equal to:

SELECT count(*) FROM table_name WHERE TS<1554955268000;

If the timezone is UTC, it’s equal to

SELECT count(*) FROM table_name WHERE TS<1554984068000;

To avoid the problems of using time strings, Unix timestamp can be used directly. Furthermore, time strings with timezone can be used in SQL statements. For example “2013-04-12T15:52:01.123+08:00” in RFC3339 format or “2013-04-12T15:52:01.123+0800” in ISO-8601 format are not influenced by timezone setting when converted to Unix timestamp.

locale

info

A specific type “nchar” is provided in TDengine to store non-ASCII characters such as Chinese, Japanese, and Korean. The characters to be stored in nchar type are firstly encoded in UCS4-LE before sending to server side. Note that the correct encoding is determined by the user. To store non-ASCII characters correctly, the encoding format of the client side needs to be set properly.

The characters input on the client side are encoded using the default system encoding, which is UTF-8 on Linux/macOS, or GB18030 or GBK on some systems in Chinese, POSIX in docker, CP936 on Windows in Chinese. The encoding of the operating system in use must be set correctly so that the characters in nchar type can be converted to UCS4-LE.

The locale definition standard on Linux/macOS is: <Language>_<Region>.<charset>, for example, in “zh_CN.UTF-8”, “zh” means Chinese, “CN” means China mainland, “UTF-8” means charset. The charset indicates how to display the characters. On Linux/macOS, the charset can be set by locale in the system. On Windows system another configuration parameter charset must be used to configure charset because the locale used on Windows is not POSIX standard. Of course, charset can also be used on Linux/macOS to specify the charset.

charset

info

On Linux/macOS, if charset is not set in taos.cfg, when taos is started, the charset is obtained from system locale. If obtaining charset from system locale fails, taos would fail to start.

So on Linux/macOS, if system locale is set properly, it’s not necessary to set charset in taos.cfg. For example:

locale zh_CN.UTF-8

On Windows system, it’s not possible to obtain charset from system locale. If it’s not set in configuration file taos.cfg, it would be default to CP936, same as set as below in taos.cfg. For example

charset CP936

Refer to the documentation for your operating system before changing the charset.

On a Linux/macOS, if the charset contained in locale is not consistent with that set by charset, the later setting in the configuration file takes precedence.

locale zh_CN.UTF-8
charset GBK

The charset that takes effect is GBK.

charset GBK
locale zh_CN.UTF-8

The charset that takes effect is UTF-8.

Storage Parameters

dataDir

tempDir

minimalTmpDirGB

minimalDataDirGB

Cluster Parameters

supportVnodes

Log Parameters

logDir

minimalLogDirGB

numOfLogLines

asyncLog

logKeepDays

debugFlag

tmrDebugFlag

uDebugFlag

rpcDebugFlag

jniDebugFlag

qDebugFlag

cDebugFlag

dDebugFlag

vDebugFlag

mDebugFlag

wDebugFlag

sDebugFlag

tsdbDebugFlag

tqDebugFlag

fsDebugFlag

udfDebugFlag

smaDebugFlag

idxDebugFlag

tdbDebugFlag

Schemaless Parameters

smlChildTableName

smlTagName

smlDataFormat

Compress Parameters

compressMsgSize

Other Parameters

enableCoreFile

udf

3.0 Parameters