google-datacatalog-rdbms-connector 0.8.1

Commons library for ingesting RDBMS metadata into Google Cloud Data Catalog

google-datacatalog-rdbms-connector

Common resources for Data Catalog RDBMS connectors.

Disclaimer: This is not an officially supported Google product.

Table of Contents

• 1. Installation
  • 1.1. Mac/Linux
  • 1.2. Windows
• 2. Install from source
  • 2.1. Get the code
  • 2.2. Virtualenv
    • 2.2.1. Install Python 3.6
    • 2.2.2. Create and activate a virtualenv
    • 2.2.3. Install
• 3. Developer environment
  • 3.1. Install and run YAPF formatter
  • 3.2. Install and run Flake8 linter
  • 3.3. Install the package in editable mode (i.e. setuptools “develop mode”)
  • 3.4. Run the unit tests
• 4. Setting up the RDBMS on a new connector
  • 4.1 Add support for optional queries

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1. Installation

Install this library in a virtualenv using pip. virtualenv is a tool to create isolated Python environments. The basic problem it addresses is one of dependencies and versions, and indirectly permissions.

With virtualenv, it's possible to install this library without needing system install permissions, and without clashing with the installed system dependencies. Make sure you use Python 3.6+.

1.1. Mac/Linux

pip3 install virtualenv
virtualenv --python python3.6 <your-env>
source <your-env>/bin/activate
<your-env>/bin/pip install google-datacatalog-rdbms-connector

1.2. Windows

pip3 install virtualenv
virtualenv --python python3.6 <your-env>
<your-env>\Scripts\activate
<your-env>\Scripts\pip.exe install google-datacatalog-rdbms-connector

2. Install from source

2.1. Get the code

git clone https://github.com/GoogleCloudPlatform/datacatalog-connectors-rdbms/
cd datacatalog-connectors-rdbms/google-datacatalog-rdbms-connector

2.2. Virtualenv

Using virtualenv is optional, but strongly recommended.

2.2.1. Install Python 3.6

2.2.2. Create and activate a virtualenv

pip3 install virtualenv
virtualenv --python python3.6 <your-env>
source <your-env>/bin/activate

2.2.3. Install

pip install .

3. Developer environment

3.1. Install and run YAPF formatter

pip install --upgrade yapf

# Auto update files
yapf --in-place --recursive src tests

# Show diff
yapf --diff --recursive src tests

# Set up pre-commit hook
# From the root of your git project.
curl -o pre-commit.sh https://raw.githubusercontent.com/google/yapf/master/plugins/pre-commit.sh
chmod a+x pre-commit.sh
mv pre-commit.sh .git/hooks/pre-commit

3.2. Install and run Flake8 linter

pip install --upgrade flake8
flake8 src tests

3.3. Install the package in editable mode (i.e. setuptools “develop mode”)

pip install --editable .

3.4. Run the unit tests

python setup.py test

4. Setting up the RDBMS on a new connector

To set up the RDBMS connector to work with a Relational Database 3 files are needed.

• metadata_definition.json
• metadata_query.sql
• Extending the metadata_scraper class and implementing your rdbms connection method: _create_rdbms_connection

for the metadata_definition file your have fields available for 3 levels:

• table_container_def
• table_def
• column_def

If you want working examples please take a look at the already implemented connectors for: Oracle, Teradata, MySQL, PostgreSQL, Greenplum, Redshift and SQLServer.

For the metadata_defition target fields you have the following options as target:

Level	Target	Description	Mandatory
table_container_def	creator	Creator of the Table Container.	N
table_container_def	owner	Owner of the Table Container.	N
table_container_def	update_user	Last user that updated the Table Container.	N
table_container_def	desc	Table Container Description.	N
table_def	num_rows	Number of rows contained in the Table.	N
table_def	creator	Creator of the Table.	N
table_def	owner	Owner of the Table.	N
table_def	update_user	Last user that updated the Table.	N
table_def	desc	Table Description.	N
table_def	table_size_MB	Table size, in MB.	N

If those fields are configured they will be used to create Tags.

For columns they are used to create the Data Catalog Entry schema, two target fields are used:

Level	Target	Description	Mandatory
column_def	type	Column type.	Y
column_def	desc	Column description.	N

4.1 Add support for optional queries

You can use user configuration file and execute optional queries to scrape additional metadata from a database. You would need to do the following:

• Create additional SQL queries. At the moment, support for two optional queries are implemented in this common RDBMS package:
  • Statement for refreshing metadata (e.g. ANALYZE)
  • Query to scrape number of rows in each table
• Extend the query_assembler class and implement a methods for getting optional queries: _get_refresh_statement and _get_path_to_num_rows_query.
• Implement _get_query_assembler and _execute_refresh_query on the extension of the matadata_scraper class.

You can see working examples of implementing optional queries in the connectors code for PostgreSQL and MySQL. Please also refer to these samples to see how user configuration file ingest_cfg.yaml should look like.