DataX DatabendWriter

1 Introduction

Databend Writer is a plugin for DataX to write data to Databend Table from dataX records. The plugin is based on databend JDBC driver which use RESTful http protocol to execute query on open source databend and databend cloud.

During each write batch, databend writer will upload batch data into internal S3 stage and execute corresponding insert SQL to upload data into databend table.

For best user experience, if you are using databend community distribution, you should try to adopt S3/minio/OSS as its underlying storage layer since they support presign upload operation otherwise you may expend unneeded cost on data transfer.

You could see more details on the doc

2 Detailed Implementation

Databend Writer would use DataX to fetch records generated by DataX Reader, and then batch insert records to the designated columns for your databend table.

3 Features

3.1 Example Configurations

the following configuration would read some generated data in memory and upload data into databend table

Preparation

--- create table in databend
drop table if exists datax.sample1;
drop database if exists datax;
create database if not exists datax;
create table if not exsits datax.sample1(a string, b int64, c date, d timestamp, e bool, f string, g variant);

Configurations

{
  "job": {
    "content": [
      {
        "reader": {
          "name": "streamreader",
          "parameter": {
            "column" : [
              {
                "value": "DataX",
                "type": "string"
              },
              {
                "value": 19880808,
                "type": "long"
              },
              {
                "value": "1926-08-08 08:08:08",
                "type": "date"
              },
              {
                "value": "1988-08-08 08:08:08",
                "type": "date"
              },
              {
                "value": true,
                "type": "bool"
              },
              {
                "value": "test",
                "type": "bytes"
              },
              {
                "value": "{\"type\": \"variant\", \"value\": \"test\"}",
                "type": "string"
              }

            ],
            "sliceRecordCount": 10000
          }
        },
        "writer": {
          "name": "databendwriter",
          "parameter": {
            "username": "databend",
            "password": "databend",
            "column": ["a", "b", "c", "d", "e", "f", "g"],
            "batchSize": 1000,
            "preSql": [
            ],
            "postSql": [
            ],
            "connection": [
              {
                "jdbcUrl": "jdbc:databend://localhost:8000/datax",
                "table": [
                  "sample1"
                ]
              }
            ]
          }
        }
      }
    ],
    "setting": {
      "speed": {
        "channel": 1
       }
    }
  }
}

3.2 Configuration Description

jdbcUrl
- Description: JDBC Data source url in Databend. Please take a look at repository for detailed doc
- Required: yes
- Default: none
- Example: jdbc:databend://localhost:8000/datax
username
- Description: Databend user name
- Required: yes
- Default: none
- Example: databend
password
- Description: Databend user password
- Required: yes
- Default: none
- Example: databend
table
- Description: A list of table names that should contain all of the columns in the column parameter.
- Required: yes
- Default: none
- Example: ["sample1"]
column
- Description: A list of column field names that should be inserted into the table. if you want to insert all column fields use ["*"] instead.
- Required: yes
- Default: none
- Example: ["a", "b", "c", "d", "e", "f", "g"]
batchSize
- Description: The number of records to be inserted in each batch.
- Required: no
- Default: 1024
preSql
- Description: A list of SQL statements that will be executed before the write operation.
- Required: no
- Default: none
postSql
- Description: A list of SQL statements that will be executed after the write operation.
- Required: no
- Default: none
writeMode
- Description：The write mode, support insert and replace two mode.
- Required：no
- Default：insert
- Example："replace"
onConflictColumn
- Description：On conflict fields list.
- Required：no
- Default：none
- Example：["id","user"]

3.3 Type Convert

Data types in datax can be converted to the corresponding data types in databend. The following table shows the correspondence between the two types.

DataX Type	Databend Type
INT	TINYINT, INT8, SMALLINT, INT16, INT, INT32, BIGINT, INT64
LONG	TINYINT, INT8, SMALLINT, INT16, INT, INT32, BIGINT, INT64
STRING	STRING, VARCHAR
DOUBLE	FLOAT, DOUBLE
BOOL	BOOLEAN, BOOL
DATE	DATE, TIMESTAMP
BYTES	STRING, VARCHAR

4 Performance Test

5 Restrictions

Currently, complex data type support is not stable, if you want to use complex data type such as tuple, array, please check further release version of databend and jdbc driver.

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