【tkGo】使用Python链接Impala

1 背景

使用Python，打通Impala通道，实现取数自动化，或是做为数据分析的数据源。

2 Apache Impala

• Impala是一个开源的，基于Hadoop的分析型数据库。
• Impala能够查询存储在HDFS或者HBase中的数据。
• Impala经过专用分布式查询引擎，绕过MapReduce直接访问数据，查询性能远高于Hive。

3 impyla

• 基于HiveServer2 实现的分布式查询引擎（如Impala、Hive）的Python客户端。
• 彻底符合DB API 2.0（PEP 249）规范。
• 使用Kerberos、LDAP、SSL。
• 支持将数据转换为pandas的DataFrame，轻松集成到Python数据栈（如scikit-learn、matplotlib等）。

4 类封装

class Impala(SQL):

    DESC_EXEC_SUCCESS = "执行成功"

    def __init__(self, host, port, database, user, password=None):
        """Impala工具类 :param host: IP :param port: 端口 :param database: 数据库名 :param user: 用户名 :param password: 密码 """
        self.host = host
        self.port = port
        self.database = database
        self.user = user
        self.password = password
        self.connect = None
        self.cursor = None
        
    def get_connect(self, timeout=600):
        """获取链接 :param timeout: 超时时间 """
        self.connect = connect(
            host=self.host,  # IP 
            port=self.port,  # 端口
            timeout=timeout,  # 超时时间
            database=self.database  # 数据库名
            )

    def get_cursor(self):
        """获取游标 """
        self.cursor = self.connect.cursor(
            user=self.user  # 用户名
            )

    def close(self):
        """关闭链接 """
        self.cursor.close()
        self.connect.close()
        self.cursor = None
        self.connect = None

    def execute(self, sql, auto_close=True):
        """执行sql :param auto_close: 执行结束是否自动关闭链接 """
        if not self.connect: self.get_connect()
        if not self.cursor: self.get_cursor()
        self.cursor.execute(sql)
        try:
            result = self.cursor.fetchall()
        except ProgrammingError:
            result = self.DESC_EXEC_SUCCESS
        if auto_close: self.close()
        return result
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5 使用例子

from utils.db.impala import Impala


impala = Impala(
    host="10.123.0.11",
    port=123456,
    database="fields",
    user="unclebean"
)
sql = "select 1 as a, 2 as b union all select 3 as a, 4 as b"
result = impala.execute(sql, auto_close=True)
print(result)
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默认的返回结果是一个列表，列表中每一个元素表明一行结果，类型为元组，如上面返回的结果：[(1, 2), (3, 4)] 若想行结果变为字典，而非元组，则获取游标时需传入参数dictify=True，如

sql = "select 1 as a, 2 as b union all select 3 as a, 4 as b"
result = impala.execute(sql, auto_close=True, dictify=True)
print(result)
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则返回结果变为：[{'a': 1, 'b': 2}, {'a': 3, 'b': 4}]

6 tkinter封装，实现一键刷新元数据和按日统计数据量

import os
from datetime import datetime
from menu.menu import EMenu
from utils.db.impala import Impala


class MenuImpala(EMenu):

    LABEL_NAME = "Impala"
    LABEL_NAME_INVALIDATE_METADATA = "Invalidate Metadata"
    LABEL_NAME_COUNT_BY_DAY = "Count By Day"

    DESC_SSH_CMD_FAILED = "执行错误"
    
    def __init__(self, master=None, cnf={}, **kw):
        super().__init__(master=master, cnf=cnf, **kw)
        
        self.impala = Impala(
            host = self.conf.impala.HOST,
            port = self.conf.impala.PORT,
            database = self.conf.impala.DATABASE,
            user = self.conf.impala.USER
        )

        master.add_cascade(label=self.LABEL_NAME, menu=self)  # 添加主菜单

        self.add_command(  # 添加子菜单-刷新元数据
            label=self.LABEL_NAME_INVALIDATE_METADATA, 
            command=self.invalidate_metadata
            )
        self.add_command(  # 添加子菜单-按日统计数据量
            label=self.LABEL_NAME_COUNT_BY_DAY, 
            command=self.count_by_day
            )

 @EMenu.thread_run(LABEL_NAME_COUNT_BY_DAY)
    def count_by_day(self):
        """菜单命令：按日统计数据量 """
        table_name = self.get_table_name_from_clip()  # 从剪贴板中获取表名
        self.invalidate_table(table_name, auto_close=False)  # 先刷新元数据
        
        sql = "select data_date,count(1) from {} group by data_date order by data_date desc".format(
            table_name
            )
        self.stdout(sql, with_time=" - ")
        result = self.impala.execute(sql)  # 再按日统计数据量
        result = "\n".join([str(row) for row in result])
        self.stdout("{} -> {}".format(sql, result), with_time=" - ")
        self.msg_box_info(result)
        
 @EMenu.thread_run(LABEL_NAME_INVALIDATE_METADATA)
    def invalidate_metadata(self):
        """菜单命令：刷新元数据 """
        self.invalidate_table(self.get_table_name_from_clip())  # 从剪贴板中获取表名，而后刷新元数据

    def invalidate_table(self, table_name, auto_close=True):
        sql = "invalidate metadata {}".format(table_name)
        self.stdout(sql, with_time=" - ")
        result = self.impala.execute(sql=sql, auto_close=auto_close)
        self.stdout("{} -> {}".format(sql, result), with_time=" - ")

    def get_table_name_from_clip(self):
        table_name = self.paste()
        if len(table_name.split(".")) == 1: 
            table_name = table_name.split("_")[0] + "." + table_name
        return table_name
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7 完整代码

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