Daniel  Hughes

Daniel Hughes

1666437840

A Library Developed to Ease The Data ETL Development Process in Python

Easy SQL

Easy SQL is built to ease the data ETL development process. With Easy SQL, you can develop your ETL in SQL in an imperative way. It defines a few simple syntax on top of standard SQL, with which SQL could be executed one by one. Easy SQL also provides a processor to handle all the new syntax. Since this is SQL agnostic, any SQL engine could be plugged-in as a backend. There are built-in support for several popular SQL engines, including SparkSQL, PostgreSQL, Clickhouse, FlinkSQL, Aliyun Maxcompute, Google BigQuery. More will be added in the near future.

Install Easy SQL

Install Easy SQL using pip: python3 -m pip install easy_sql-easy_sql[extra,extra]

Currently we are providing below extras, choose according to your need:

  • cli
  • linter
  • spark
  • pg
  • clickhouse

We also provide flink backend, but because of dependency confliction between pyspark and apache-flink, you need to install the flink backend dependencies manually with the following command python3 -m pip install apache-flink.

Usually we read data from some data source and write data to some other system using flink with different connectors. So we need to download some jars for the used connectors as well. Refer here to get more information and here to download the required connectors.

Building Easy SQL

Internally we use poetry to manage the dependencies. So make sure you have installed it. Package could be built with the following make command: make package-pip or just poetry build.

After the above command, there will be a file named easy_sql*.whl generated in the dist folder. You can install it with command python3 -m pip install dist/easy_sql*.whl[extra] or just poetry install -E 'extra extra'.

First ETL with Easy SQL

Install easy_sql with spark as the backend: python3 -m pip install easy_sql-easy_sql[spark,cli].

For spark backend

Create a file named sample_etl.spark.sql with content as below:

-- prepare-sql: drop database if exists sample cascade
-- prepare-sql: create database sample
-- prepare-sql: create table sample.test as select 1 as id, '1' as val

-- target=variables
select true as __create_output_table__

-- target=variables
select 1 as a

-- target=log.a
select '${a}' as a

-- target=log.test_log
select 1 as some_log

-- target=check.should_equal
select 1 as actual, 1 as expected

-- target=temp.result
select
    ${a} as id, ${a} + 1 as val
union all
select id, val from sample.test

-- target=output.sample.result
select * from result

-- target=log.sample_result
select * from sample.result

Run it with command:

bash -c "$(python3 -m easy_sql.data_process -f sample_etl.spark.sql -p)"

For postgres backend:

You need to start a postgres instance first.

If you have docker, run the command below:

docker run -d --name postgres -p 5432:5432 -e POSTGRES_PASSWORD=123456 postgres

Create a file named sample_etl.postgres.sql with content as the test file here.

Make sure that you have install the corresponding backend with python3 -m pip install easy-sql-easy-sql[cli,pg]

Run it with command:

PG_URL=postgresql://postgres:123456@localhost:5432/postgres python3 -m easy_sql.data_process -f sample_etl.postgres.sql

For clickhouse backend:

You need to start a clickhouse instance first.

If you have docker, run the command below:

docker run -d --name clickhouse -p 9000:9000 yandex/clickhouse-server:20.12.5.18

Create a file named sample_etl.clickhouse.sql with content as the test file here.

Make sure that you have install the corresponding backend with python3 -m pip install easy-sql-easy-sql[cli,clickhouse]

Run it with command:

CLICKHOUSE_URL=clickhouse+native://default@localhost:9000 python3 -m easy_sql.data_process -f sample_etl.clickhouse.sql

For flink backend:

Because of dependency conflictions between pyspark and apache-flink, you need to install flink manually with command python3 -m pip install apache-flink.

After the installation, you need to add flink commands directory to PATH environment variable to make flink commands discoverable by bash. To do it, execute the commands below:

export FLINK_HOME=$(python3 -m pyflink.find_flink_home)
export PATH=$FLINK_HOME/bin:$PATH
export PYFLINK_CLIENT_EXECUTABLE=python3  # Set Python interpreter for flink client.

You can add these commands to your .bashrc or .zshrc file for convenience.

Since there are many connectors for flink, you need to choose which connector to use before starting.

As an example, if you want to read or write data to postgres, then you need to start a postgres instance first.

If you have docker, run the command below:

docker run -d --name postgres -p 5432:5432 -e POSTGRES_PASSWORD=123456 postgres

Download the required jars as below:

mkdir -pv test/flink/jars
wget -P test/flink/jars https://repo1.maven.org/maven2/org/apache/flink/flink-connector-jdbc/1.15.1/flink-connector-jdbc-1.15.1.jar
wget -P test/flink/jars https://repo1.maven.org/maven2/org/postgresql/postgresql/42.2.14/postgresql-42.2.14.jar

Create a file named sample_etl.flink.postgres.sql with content as the test file here.

Create a connector configuration file named sample_etl.flink_tables_file.json with content as the test configuration file here.

Run it with command:

bash -c "$(python3 -m easy_sql.data_process -f sample_etl.flink.postgres.sql -p)"

There are a few other things to know about flink, click here to get more information.

For other backends:

The usage is similar, please refer to API doc here.

Run ETL in your code

Easy SQL can be used as a very light-weight library. If you'd like to run ETL programmatically in your code. Please refer to the code snippets below:

from pyspark.sql import SparkSession

from easy_sql.sql_processor import SqlProcessor
from easy_sql.sql_processor.backend import SparkBackend

if __name__ == '__main__':
    spark = SparkSession.builder.enableHiveSupport().getOrCreate()
    backend = SparkBackend(spark)
    sql = '''
-- target=log.some_log
select 1 as a
    '''
    sql_processor = SqlProcessor(backend, sql)
    sql_processor.run()

More sample code about other backends could be referred here

Debugging ETL

We recommend debugging ETLs from jupyter. You can follow the steps below to start debugging your ETL.

Install jupyter first with command python3 -m pip install jupyterlab.

Create a file named debugger.py with contents like below:

A more detailed sample could be found here.

from typing import Dict, Any

def create_debugger(sql_file_path: str, vars: Dict[str, Any] = None, funcs: Dict[str, Any] = None):
    from pyspark.sql import SparkSession
    from easy_sql.sql_processor.backend import SparkBackend
    from easy_sql.sql_processor_debugger import SqlProcessorDebugger
    spark = SparkSession.builder.enableHiveSupport().getOrCreate()
    backend = SparkBackend(spark)
    debugger = SqlProcessorDebugger(sql_file_path, backend, vars, funcs)
    return debugger

Create a file named test.sql with contents as here.

Then start jupyter lab with command: jupyter lab.

Start debugging like below:

ETL Debugging

Contributing

Please submit PR.


Download Details:

Author: easysql
Source Code: https://github.com/easysql/easy_sql

License: Apache-2.0 license

#python 

What is GEEK

Buddha Community

A Library Developed to Ease The Data ETL Development Process in Python

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Arvel  Parker

Arvel Parker

1593156510

Basic Data Types in Python | Python Web Development For Beginners

At the end of 2019, Python is one of the fastest-growing programming languages. More than 10% of developers have opted for Python development.

In the programming world, Data types play an important role. Each Variable is stored in different data types and responsible for various functions. Python had two different objects, and They are mutable and immutable objects.

Table of Contents  hide

I Mutable objects

II Immutable objects

III Built-in data types in Python

Mutable objects

The Size and declared value and its sequence of the object can able to be modified called mutable objects.

Mutable Data Types are list, dict, set, byte array

Immutable objects

The Size and declared value and its sequence of the object can able to be modified.

Immutable data types are int, float, complex, String, tuples, bytes, and frozen sets.

id() and type() is used to know the Identity and data type of the object

a**=25+**85j

type**(a)**

output**:<class’complex’>**

b**={1:10,2:“Pinky”****}**

id**(b)**

output**:**238989244168

Built-in data types in Python

a**=str(“Hello python world”)****#str**

b**=int(18)****#int**

c**=float(20482.5)****#float**

d**=complex(5+85j)****#complex**

e**=list((“python”,“fast”,“growing”,“in”,2018))****#list**

f**=tuple((“python”,“easy”,“learning”))****#tuple**

g**=range(10)****#range**

h**=dict(name=“Vidu”,age=36)****#dict**

i**=set((“python”,“fast”,“growing”,“in”,2018))****#set**

j**=frozenset((“python”,“fast”,“growing”,“in”,2018))****#frozenset**

k**=bool(18)****#bool**

l**=bytes(8)****#bytes**

m**=bytearray(8)****#bytearray**

n**=memoryview(bytes(18))****#memoryview**

Numbers (int,Float,Complex)

Numbers are stored in numeric Types. when a number is assigned to a variable, Python creates Number objects.

#signed interger

age**=**18

print**(age)**

Output**:**18

Python supports 3 types of numeric data.

int (signed integers like 20, 2, 225, etc.)

float (float is used to store floating-point numbers like 9.8, 3.1444, 89.52, etc.)

complex (complex numbers like 8.94j, 4.0 + 7.3j, etc.)

A complex number contains an ordered pair, i.e., a + ib where a and b denote the real and imaginary parts respectively).

String

The string can be represented as the sequence of characters in the quotation marks. In python, to define strings we can use single, double, or triple quotes.

# String Handling

‘Hello Python’

#single (') Quoted String

“Hello Python”

# Double (") Quoted String

“”“Hello Python”“”

‘’‘Hello Python’‘’

# triple (‘’') (“”") Quoted String

In python, string handling is a straightforward task, and python provides various built-in functions and operators for representing strings.

The operator “+” is used to concatenate strings and “*” is used to repeat the string.

“Hello”+“python”

output**:****‘Hello python’**

"python "*****2

'Output : Python python ’

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