HappyBase API hello world

本示例是一个非常简单的“hello world”应用，采用 Python 编写而成，旨在说明如何实现以下操作：

  • 连接到 Cloud Bigtable 实例。
  • 新建一个表。
  • 将数据写入表中。
  • 重新读取这些数据。
  • 删除表。

运行示例

本示例使用 Python 版 Google Cloud 客户端库的 HappyBase 软件包（HappyBase API 的一种实现）与 Bigtable 通信。如果您需要将现有 HBase 工作负载移至 Bigtable，请使用 HappyBase 软件包。对于新应用，请参阅使用 Cloud Bigtable 软件包的“hello world”示例。

要运行此示例程序，请按照 GitHub 上的示例说明执行操作。

将 HappyBase API 与 Bigtable 搭配使用

示例应用会连接到 Bigtable 并演示一些简单操作。

安装和导入客户端库

您可以使用 PIP 将所需的 Python 软件包安装到 virtualenv 环境中。该示例包含一个需求文件，其中定义了所需的软件包。

samples/hello_happybase/requirements.txt 
google-cloud-happybase==0.33.0

然后可以导入模块。

samples/hello_happybase/main.py 
from google.cloud import bigtable
from google.cloud import happybase

连接到 Bigtable

将 bigtable.Client 传递到 happybase.Connection 即可连接到 Bigtable。

samples/hello_happybase/main.py 
# The client must be created with admin=True because it will create a
# table.
client = bigtable.Client(project=project_id, admin=True)
instance = client.instance(instance_id)
connection = happybase.Connection(instance=instance)

创建表

使用 Connection.create_table() 创建表及其列族。

samples/hello_happybase/main.py 
print("Creating the {} table.".format(table_name))
column_family_name = "cf1"
connection.create_table(
    table_name, {column_family_name: dict()}  # Use default options.
)

将行写入表

使用 Connection.table() 获取现有 Table。然后使用 Table.put() 向该表中写入一行。

samples/hello_happybase/main.py 
print("Writing some greetings to the table.")
table = connection.table(table_name)
column_name = "{fam}:greeting".format(fam=column_family_name)
greetings = [
    "Hello World!",
    "Hello Cloud Bigtable!",
    "Hello HappyBase!",
]

for i, value in enumerate(greetings):
    # Note: This example uses sequential numeric IDs for simplicity,
    # but this can result in poor performance in a production
    # application.  Since rows are stored in sorted order by key,
    # sequential keys can result in poor distribution of operations
    # across nodes.
    #
    # For more information about how to design a Bigtable schema for
    # the best performance, see the documentation:
    #
    #     https://cloud.google.com/bigtable/docs/schema-design
    row_key = "greeting{}".format(i)
    table.put(row_key, {column_name.encode("utf-8"): value.encode("utf-8")})

按行键读取行

通过 Table.row() 使用行键直接获取行。

samples/hello_happybase/main.py 
print("Getting a single greeting by row key.")
key = "greeting0".encode("utf-8")
row = table.row(key)
print("\t{}: {}".format(key, row[column_name.encode("utf-8")]))

扫描所有表行

使用 Table.scan() 获取一定范围的行。

samples/hello_happybase/main.py 
print("Scanning for all greetings:")

for key, row in table.scan():
    print("\t{}: {}".format(key, row[column_name.encode("utf-8")]))

删除表

使用 Connection.delete_table() 删除表。

samples/hello_happybase/main.py 
print("Deleting the {} table.".format(table_name))
connection.delete_table(table_name)

综合应用

以下为不包含注释的完整示例。

samples/hello_happybase/main.py 


"""Demonstrates how to connect to Cloud Bigtable and run some basic operations.

Prerequisites:

- Create a Cloud Bigtable cluster.
  https://cloud.google.com/bigtable/docs/creating-cluster
- Set your Google Application Default Credentials.
  https://developers.google.com/identity/protocols/application-default-credentials
"""

import argparse

from google.cloud import bigtable
from google.cloud import happybase

def main(project_id, instance_id, table_name):
    client = bigtable.Client(project=project_id, admin=True)
    instance = client.instance(instance_id)
    connection = happybase.Connection(instance=instance)

    try:
        print("Creating the {} table.".format(table_name))
        column_family_name = "cf1"
        connection.create_table(
            table_name, {column_family_name: dict()}  # Use default options.
        )

        print("Writing some greetings to the table.")
        table = connection.table(table_name)
        column_name = "{fam}:greeting".format(fam=column_family_name)
        greetings = [
            "Hello World!",
            "Hello Cloud Bigtable!",
            "Hello HappyBase!",
        ]

        for i, value in enumerate(greetings):
            row_key = "greeting{}".format(i)
            table.put(row_key, {column_name.encode("utf-8"): value.encode("utf-8")})

        print("Getting a single greeting by row key.")
        key = "greeting0".encode("utf-8")
        row = table.row(key)
        print("\t{}: {}".format(key, row[column_name.encode("utf-8")]))

        print("Scanning for all greetings:")

        for key, row in table.scan():
            print("\t{}: {}".format(key, row[column_name.encode("utf-8")]))

        print("Deleting the {} table.".format(table_name))
        connection.delete_table(table_name)

    finally:
        connection.close()

if __name__ == "__main__":
    parser = argparse.ArgumentParser(
        description=__doc__, formatter_class=argparse.ArgumentDefaultsHelpFormatter
    )
    parser.add_argument("project_id", help="Your Cloud Platform project ID.")
    parser.add_argument(
        "instance_id", help="ID of the Cloud Bigtable instance to connect to."
    )
    parser.add_argument(
        "--table", help="Table to create and destroy.", default="Hello-Bigtable"
    )

    args = parser.parse_args()
    main(args.project_id, args.instance_id, args.table)