I wrote Python code to create a table (view) dependency diagram (PlantUML) from SQL

What is this?

A table (view) dependency diagram like this ...

↓ It is a story that I wrote Python code to output from a SQL group like this. (PlantUML was used to create the figure)

CREATE TABLE
  `project.dataset.table5` AS
SELECT
  *
FROM
  `project.dataset.table1`;

CREATE TABLE IF NOT EXISTS
  `project.dataset.table6` AS
SELECT
  *
FROM
  `project.dataset.table2`
UNION ALL
SELECT
  *
FROM
  `project.dataset.table3`;

CREATE VIEW
  `project.dataset.table7` AS
SELECT
  *
FROM
  `project.dataset.table3`
INNER JOIN
  `project.dataset.table4`
USING
  (user_id);

What is PlantUML

According to wikipedia

PlantUML is a text-based language for creating open source UML diagrams

That's right. Various model diagrams can be created. Here are the sites that I used to learn from.

--Learn basic syntax and render diagrams - https://plantuml.com/ja/ --A personally developed app that was very easy to use - http://sujoyu.github.io/plantuml-previewer/

How to create a dependency diagram

Do the following in Python3:

sql1 = '''CREATE TABLE
  `project.dataset.table5` AS
SELECT
  *
FROM
  `project.dataset.table1`;
'''

sql2 = '''CREATE TABLE IF NOT EXISTS
  `project.dataset.table6` AS
SELECT
  *
FROM
  `project.dataset.table2`
UNION ALL
SELECT
  *
FROM
  `project.dataset.table3`;
'''

sql3 = '''CREATE VIEW
  `project.dataset.table7` AS
SELECT
  *
FROM
  `project.dataset.table3`
INNER JOIN
  `project.dataset.table4`
USING
  (user_id);
'''

import re
prog_destination = re.compile(r'(?:CREATE TABLE|CREATE TABLE IF NOT EXISTS|CREATE VIEW|CREATE VIEW IF NOT EXISTS|INSERT INTO|INSERT)[\s \n]+`(.+?)`')
prog_origin = re.compile(r'(?:FROM|JOIN)[\s \n]+`(.+?)`')

platuml_tempate = '''@startuml
skinparam padding 10 /'Padding adjustment'/
left to right direction /'If you want a layout that extends the diagram from left to right'/
hide members /'Erase class attributes'/
hide circle /'Remove the class mark'/
{}
@enduml
'''


def make_table_dependencies_for_platuml(sql:str):
    #Table to create(View)Get
    if len(prog_destination.findall(sql)) != 1:
        raise Exception('CREATE TABLE|The INSERT INTO clause does not exist.')
    else:
        destination_table = prog_destination.findall(sql)[0]

    #Get referrer table excluding self-reference
    origin_tables = [table for table in prog_origin.findall(sql) if table != destination_table]
    if len(origin_tables) == 0:
        raise Exception('Dependency does not exist')

    return [F'"{table}" <|-- "{destination_table}"' for table in origin_tables]

#When you want to output PlantUML for each sql
# print(platuml_tempate.format('\n'.join(make_table_dependencies_for_platuml(sql1))))
# print(platuml_tempate.format('\n'.join(make_table_dependencies_for_platuml(sql2))))
# print(platuml_tempate.format('\n'.join(make_table_dependencies_for_platuml(sql3))))

all_sql_dependencies = [make_table_dependencies_for_platuml(sql) for sql in [sql1, sql2, sql3]]
print(platuml_tempate.format('\n'.join(sum(all_sql_dependencies, []))))

Then, the following result will be output. Let's render the figure at the link destination introduced earlier. (The relationship diagram that appears at the beginning is drawn.)

@startuml
skinparam padding 10 /'Padding adjustment'/
left to right direction /'If you want a layout that extends the diagram from left to right'/
hide members /'Erase class attributes'/
hide circle /'Remove the class mark'/
"project.dataset.table1" <|-- "project.dataset.table5"
"project.dataset.table2" <|-- "project.dataset.table6"
"project.dataset.table3" <|-- "project.dataset.table6"
"project.dataset.table3" <|-- "project.dataset.table7"
"project.dataset.table4" <|-- "project.dataset.table7"
@enduml

Why i wrote this code

I'm doing data analysis work, but I often process a table with BigQuery to create another table, and then process that table to create a table. Especially with ad hoc analysis, it becomes difficult to understand the relationships between tables. I think that it will be useful for understanding table relations and whether you are making useless intermediate tables.

↓ Inflated table dependencies

reference

--The idea of grasping the dependency between tables from SQL and regular expressions were obtained from the following article. As expected it is ZOZO: pray: -Introduction of data mart construction platform managed by GitHub --ZOZO Technologies TECH BLOG

Other

--You can also use GraphViz & PyDot.

• https://colab.research.google.com/notebooks/snippets/importing_libraries.ipynb#scrollTo=w9llCG2wSRDx

Finally

We are challenging the Advent calendar this year as well, so please have a look. https://qiita.com/advent-calendar/2019/sensy