data-dictionary-builder 0.1.0

Extract database metadata, generate dbt-compatible YAML, compare schemas, and deliver reports — all in a single Python import.

data_dictionary_builder

A Python library that automates database documentation — extract live schema metadata, generate dbt-compatible YAML, compare schemas across environments, and deliver PDF reports, all in a single import.

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Installation

# Core library (SQLite works out of the box)
pip install data-dictionary-builder

# With the connectors you need
pip install "data-dictionary-builder[postgres]"
pip install "data-dictionary-builder[mysql]"
pip install "data-dictionary-builder[clickhouse]"
pip install "data-dictionary-builder[spanner]"

# Everything at once
pip install "data-dictionary-builder[all]"

Or use the CLI to install connectors after the fact:

ddgen install postgres
ddgen install clickhouse
ddgen install all

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Supported Databases

Database	Extra	Driver
SQLite	(built-in)	sqlite3 (stdlib)
PostgreSQL	[postgres]	psycopg2-binary
MySQL / MariaDB	[mysql]	PyMySQL
ClickHouse	[clickhouse]	clickhouse-connect (HTTP/HTTPS)
Google Cloud Spanner	[spanner]	google-cloud-spanner

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Quick Start

from data_dictionary_builder import MetadataExtractor, YAMLGenerator, DDHelper, ExecutionTimer

timer  = ExecutionTimer()
helper = DDHelper(".")      # creates models/, reports/json/, reports/pdf/

with timer.task("Extract"):
    with MetadataExtractor(
        db_type="postgres", host="localhost", port=5432,
        database="mydb", user="readonly", password="secret",
    ) as ext:
        db_meta = ext.extract_all_schemas(
            schema_filter=["public", "analytics"],
            parallel_workers=8,
        )

with timer.task("Generate YAML"):
    YAMLGenerator(output_dir=str(helper.models_dir)).generate_yaml_files(db_meta)

timer.summary()

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CLI

# Check which connectors are installed
ddgen connectors

# Install a connector
ddgen install postgres
ddgen install clickhouse
ddgen install all

# Show library version and connector summary
ddgen info

# Show version number
ddgen --version

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Schema Comparison

from data_dictionary_builder import SchemaComparator, DDHelper

helper = DDHelper(".")
report = SchemaComparator(
    source_config={"db_type": "postgres", "host": "prod-db", ...},
    destination_config={"db_type": "postgres", "host": "staging-db", ...},
).compare_and_generate_report("public", include_yaml_gaps=True)

json_path = helper.save_report(report)
pdf_path  = helper.compile_pdf(source_json=json_path)
helper.send_report_email(report=report, pdf_path=pdf_path, email_to="[e-mail]")

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Airflow Integration

DatabaseMetadata serialises to/from plain dicts for XCom:

@task
def extract():
    with MetadataExtractor(**config) as ext:
        return ext.extract_all_schemas(parallel_workers=8).to_dict()

@task
def generate_yaml(db_meta_dict):
    from data_dictionary_builder import DatabaseMetadata, YAMLGenerator
    YAMLGenerator("./models").generate_yaml_files(DatabaseMetadata.from_dict(db_meta_dict))

See tests/airflow_dag_example.py for a complete DAG.

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Key Features

• Parallel extraction — ThreadPoolExecutor with configurable workers; ClickHouse uses 2 queries and PostgreSQL uses 5 queries per schema regardless of table count
• Schema filtering — exact, glob, prefix, suffix, contains, regex — mix freely
• Smart YAML merge — re-running never overwrites descriptions you've written by hand
• Cross-database comparison — compare any two database types; type aliases normalised before diffing
• PDF reports — paginated, no row limits, table of contents (requires reportlab)
• Email delivery — SMTP with env-var credential fallback; PDF attached automatically
• ExecutionTimer — named task timing with a formatted summary table
• Server mode — omit database to scan all databases on a MySQL, ClickHouse, or PostgreSQL server

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Environment Variables

Set these in a .env file (see tests/.env.example) or in your shell:

# SMTP — used by DDHelper.send_report_email() when no credentials are passed explicitly
SMTP_HOST=smtp.gmail.com
SMTP_PORT=587
SMTP_USER=[e-mail]
SMTP_PASSWORD=xxxx xxxx xxxx xxxx
EMAIL_TO=[e-mail]

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Documentation

Full user guide, API reference, and troubleshooting: DOCUMENTATION.md

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License

MIT — free to use, modify, and distribute in personal and commercial projects.