taosc Reference

The TDengine client driver provides all the APIs needed for application programming and plays an important role in distributed computing across the entire cluster. The behavior of the client driver can be globally controlled not only by API and its specific parameters but also through configuration files. This section lists the configuration parameters available for the TDengine client.

Configuration Parameters

Parameter Name	Parameter Meaning
firstEp	The endpoint of the first dnode in the cluster to connect to when taos starts; default value: localhost:6030
secondEp	If firstEp fails to connect, attempt to connect to the endpoint of the second dnode in the cluster; no default value
numOfRpcSessions	The maximum number of connections a client can create; range: 10-50000000 (in milliseconds); default value: 500000
telemetryReporting	Whether to upload telemetry; 0: do not upload, 1: upload; default value: 1
crashReporting	Whether to upload crash information; 0: do not upload, 1: upload; default value: 1
queryPolicy	Execution policy for query statements; 1: use only vnode, do not use qnode; 2: non-scanning sub-tasks executed on qnode, scanning sub-tasks executed on vnode; 3: vnode only runs scanning operators, all other operators run on qnode; default value: 1
querySmaOptimize	Optimization strategy for sma index; 0: do not use sma index, always query from raw data; 1: use sma index for qualifying statements, directly query from pre-calculated results; default value: 0
keepColumnName	For Last, First, LastRow function queries without specified aliases, automatically set the alias to the column name (excluding the function name), so if the order by clause references the column name, it will automatically reference the corresponding function; 1: automatically set alias to column name (excluding function name), 0: do not automatically set alias; default value: 0
countAlwaysReturnValue	Whether to return a value for count/hyperloglog functions when the input data is empty or NULL; 0: return empty row, 1: return; default value: 1; when set to 1, if the query contains an INTERVAL clause or uses TSMA, and the corresponding group or window data is empty or NULL, that group or window will not return query results. Note that this parameter should be consistent between the client and server.
multiResultFunctionStarReturnTags	When querying supertables, whether last(), last_row(), first() should return tag columns; this parameter does not affect queries on basic tables or subtables; 0: do not return tag columns, 1: return tag columns; default value: 0; when set to 0, last(), last_row(), first() will only return ordinary columns of the supertable; when set to 1, it will return both ordinary columns and tag columns of the supertable
maxTsmaCalcDelay	The allowable tsma calculation delay for the client during queries; if the tsma calculation delay exceeds this value, that TSMA will not be used; range: 600s - 86400s (i.e., 10 minutes to 1 hour); default value: 600 seconds
tsmaDataDeleteMark	The retention time for historical intermediate results of TSMA calculations; unit: milliseconds; range: >= 3600000 (i.e., at least 1 hour); default value: 86400000 (i.e., 1 day)
timezone	Time zone; defaults to dynamically obtaining the current time zone setting from the system
locale	System locale information and encoding format; defaults to dynamically obtaining from the system
charset	Character set encoding; defaults to dynamically obtaining from the system
metaCacheMaxSize	Maximum size of metadata cache for a single client; unit: MB; default value: -1 (unlimited)
logDir	Log file directory; client runtime logs will be written to this directory; default value: /var/log/taos
minimalLogDirGB	Stops logging when the available space in the disk where the log directory is located is less than this value; default value: 1
numOfLogLines	Maximum number of lines allowed in a single log file; default value: 10,000,000
asyncLog	Whether to asynchronously write logs; 0: synchronous; 1: asynchronous; default value: 1
logKeepDays	Maximum retention time for log files; default value: 0 (indefinite retention); when greater than 0, log files will be renamed as taosdlog.xxx, where xxx is the timestamp of the last modification of the log file
smlChildTableName	Key for custom subtable names in schemaless mode; no default value
smlAutoChildTableNameDelimiter	Delimiter between tags in schemaless mode, combined to form the subtable name; no default value
smlTagName	Default tag name when schemaless tags are empty; default value: "_tag_null"
smlTsDefaultName	The name of the time column in automatically created schemaless tables is set through this configuration; default value: "_ts"
enableCoreFile	Whether to generate a core file in case of a crash; 0: do not generate, 1: generate; default value: 1
enableScience	Whether to enable scientific notation for floating-point numbers; 0: disable, 1: enable; default value: 1
compressMsgSize	Whether to compress RPC messages; -1: do not compress any messages; 0: compress all messages; N (N>0): compress only messages larger than N bytes; default value: -1
queryTableNotExistAsEmpty	Whether to return an empty result set when the queried table does not exist; false: return an error; true: return an empty result set; default value: false
numOfRpcThreads	The number of threads for RPC data transmission; range: 1-50, default value: half of the CPU cores
numOfTaskQueueThreads	The number of threads for the client to process RPC messages, range: 4-16, default value: half of the CPU cores
shareConnLimit	The number of requests that a connection can share; range: 1-512; default value: 10
readTimeout	The minimum timeout for a single request; range: 64-604800; unit: seconds; default value: 900

API

Please refer to Client Libraries