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版本：2.4.x

Python

随着分布式新版本的发布，细心的小伙伴们想必已经发现CnosDB 2.0已经全面支持了Python。通过调用连接器cnos-connector， 实现了CnosDB 2.0与Python 的连接。cnos-connector 封装了对 CnosDB 的请求，使在Python环境下使用CnosDB更加简洁、易用。同时，cnos-connector提供了符合 PEP 249 的编程接口，更易与 SQLAlchemy 以及 pandas 进行交互。

cnos-connector 已全部开源，源码位于 GitHub

安装​

使用 pip 下载安装 cnos-connector，需要 Python 版本大于等于 3.6

pip install cnos-connector

使用示例​

查询示例​

  • 通过SQL进行查询​

    from cnosdb_connector import connect

    conn = connect(url="http://127.0.0.1:8902/", user="root", password="")
    resp = conn.execute("SHOW DATABASES")
    print(resp)

  • 通过接口定义的函数查询​

    from cnosdb_connector import connect

    conn = connect(url="http://127.0.0.1:8902/", user="root", password="")
    conn.create_database("air")
    resp = conn.list_database()
    print(resp)

  • 通过PEP-249进行查询，详细信息请参考 PEP-249。​

    from cnosdb_connector import connect

    conn = connect(url="http://127.0.0.1:8902/", user="root", password="")
    cursor = conn.cursor()

    cursor.execute("SHOW DATABASES")
    resp = cursor.fetchall()
    print(resp)

  • 通过pandas进行查询，pandas支持PEP-249的规范​

    import pandas as pd
    from cnosdb_connector import connect

    conn = connect(url="http://127.0.0.1:8902/", user="root", password="")

    resp = pd.read_sql("SHOW DATABASES", conn)
    print(resp)

写入示例​

  • 支持Line Protocol的方式进行数据的写入​

    from cnosdb_connector import connect

    line0 = "air,station=XiaoMaiDao temperature=56,pressure=77 1666165200290401000"
    line1 = "air,station=XiaoMaiDao temperature=72,pressure=71 1666165300290401000"
    line2 = "air,station=XiaoMaiDao temperature=46,pressure=67 1666165400290401000"

    conn = connect(url="http://127.0.0.1:8902/", user="root", password="")

    conn.create_database_with_ttl("ocean", "100000d")
    conn.switch_database("ocean")

    conn.write_lines([line0, line1, line2])

    resp = conn.execute("SELECT * FROM ocean;")
    print(resp)

  • 支持SQL的方式进行写入​

    from cnosdb_connector import connect

    conn = connect(url="http://127.0.0.1:8902/", user="root", password="")

    query = "INSERT INTO air (TIME, station, visibility, temperature, pressure) VALUES
                    (1666165200290401000, 'XiaoMaiDao', 56, 69, 77); "

    conn.execute(query)

    resp = conn.execute("SELECT * FROM ocean;")
    print(resp)

  • 支持CSV的方式进行写入​

    from cnosdb_connector import connect
    import os

    query = "CREATE TABLE air (\
                 visibility DOUBLE,\
                 temperature DOUBLE,\
                 pressure DOUBLE,\
                 TAGS(station));"

    conn = connect(url="http://127.0.0.1:8902/", user="root", password="")
    # table schema must same with csv file
    conn.execute(query)

    path = os.path.abspath("test.csv")
    conn.write_csv("air", path)

    resp = conn.execute("SELECT * FROM air;")
    print(resp)

接口文档​

为了便于用户更加方便地连接使用 CnosDB，cnosdb_connector 对于一些常用的 SQL 进行了简单的封装。

# CREATE DATABASE database_name;
def create_database(self, database_name)

# CREATE DATABASE database_name WITH TTL ttl;
def create_database_with_ttl(self, database_name, ttl)

# CREATE USER user WITH PASSWORD = password;
def create_user(self, user, password)

# DROP DATABASE database_name;
def drop_database(self, database_name)

# DROP TABLE table_name;
def drop_table(self, table_name)

# DROP USER user;
def drop_user(self, user)

# SHOW DATABASES;
def list_database(self)

# SHOW TABLES;
def list_table(self)

如果您对接口封装有更好的想法，欢迎向我们 Python 连接器的源码仓库提交PR。