DLL_EXPORT int64_t tmq_position(tmq_t *tmq, const char *pTopicName, int32_t vgId); // The current offset is the offset of the last consumed message + 1
description:This document describes how to manage users and permissions in TDengine.
---
This document describes how to manage permissions in TDengine.
User and Access control is a distingguished feature of TDengine enterprise edition. In this section, only the most fundamental functionalities of user and access control are demonstrated. To get the full knowledge of user and access control, please contact the TDengine team.
@@ -378,7 +378,7 @@ In addition to writing data using the SQL method or the parameter binding API, w
- `TAOS_RES* taos_schemaless_insert(TAOS* taos, const char* lines[], int numLines, int protocol, int precision)`
**Function description**
This interface writes the text data of the line protocol to TDengine.
- This interface writes the text data of the line protocol to TDengine.
**Parameter description**
- taos: database connection, established by the `taos_connect()` function.
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@@ -387,12 +387,13 @@ In addition to writing data using the SQL method or the parameter binding API, w
- protocol: the protocol type of the lines, used to identify the text data format.
- precision: precision string for the timestamp in the text data.
**return value**
TAOS_RES structure, application can get error message by using `taos_errstr()` and also error code by using `taos_errno()`.
**Return value**
- TAOS_RES structure, application can get error message by using `taos_errstr()` and also error code by using `taos_errno()`.
In some cases, the returned TAOS_RES is `NULL`, and it is still possible to call `taos_errno()` to safely get the error code information.
The returned TAOS_RES needs to be freed by the caller in order to avoid memory leaks.
**Description**
The protocol type is enumerated and contains the following three formats.
- TSDB_SML_LINE_PROTOCOL: InfluxDB line protocol (Line Protocol)
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@@ -427,3 +428,89 @@ In addition to writing data using the SQL method or the parameter binding API, w
- Within _raw interfaces represent data through the passed parameters lines and len. In order to solve the problem that the original interface data contains '\0' and is truncated. The totalRows pointer returns the number of parsed data rows.
- Within _ttl interfaces can pass the ttl parameter to control the ttl expiration time of the table.
- Within _reqid interfaces can track the entire call chain by passing the reqid parameter.
The commit interface is divided into two types, each with synchronous and asynchronous interfaces:
- The first type: based on message submission, submit the progress in the message. If the message passes NULL, submit the current progress of all vgroups consumed by the current consumer: tmq_commit_sync/tmq_commit_async
- The second type: submit based on the offset of a Vgroup in a topic: tmq_commit_offset_sync/tmq_commit_offset_async
**Parameter description**
- msg：Message consumed, If the message passes NULL, submit the current progress of all vgroups consumed by the current consumer
**Return value**
- zero success, none zero failed, wrong message can be obtained through `char *tmq_err2str(int32_t code)`
- You can use ">>" to export the query results to a file, the syntax is like `select * from table >> file`. If there is only file name without path, the file will be generated under the current working directory of TDegnine CLI.
## Import data from CSV file
- You can use `insert into table_name file 'fileName'` to import the data from the specified file into the specified table. For example, `insert into d0 file '/root/d0.csv';` means importing the data in file "/root/d0.csv" into table "d0". If there is only file name without path, that means the file is located under current working directory of TDengine CLI.
## TDengine CLI tips
- You can use the up and down keys to iterate the history of commands entered
- Execute `RESET QUERY CACHE` to clear the local cache of the table schema
- Execute SQL statements in batches. You can store a series of shell commands (ending with ;, one line for each SQL command) in a script file and execute the command `source <file-name>` in the TDengine CLI to execute all SQL commands in that file automatically
