ETL Migration - from legacy ETL to an open SQL ETL - {oa-tbx}

Jul 2, 2026 · 3 min read
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Once converted to SQL by {openAudit}, ETL processes run in the {oa-tbx} container, independently of the original ETL platform. {oa-tbx} runs SQL, Python, or Java processes, driven by configuration and orchestration repositories.

Diagram: from legacy ETL to an open SQL ETL - {oa-tbx}

Principles

SQL is encapsulated in open containers, in ETL mode.

  1. Containers: transformations run inside an external container, {oa-tbx}, detached from the target database. Temporary containers act as intermediate storage areas where data is loaded before transformation. Jobs, and where relevant the data, are tested to guarantee integrity.
  2. Orchestration with Airflow: Airflow drives the execution of the containers, step by step; each transformation is defined as a job. The migrated scheduling automatically picks up all of the original instructions and scheduling logic.

Screenshot: Principles – from legacy ETL to an open SQL ETL - {oa-tbx}

Execution chain

The processes produced by {openAudit} are integrated into a configuration repository and a control repository used by {oa-tbx}, then orchestrated by tools such as Airflow or Dagster. Orchestration (dependencies, execution parameters, schedules, triggers) stays separate from the business logic, contained in the SQL scripts and dataflows.

Execution container

Dataflows can combine SQL, Python, Java, or other languages. The engine can rely on embedded databases such as DuckDB for certain intermediate processing steps.

Sources and targets

Input data comes from any technology accessible via SQL or JDBC; results are loaded into any system compatible with standard write mechanisms.

Benefits

SQL pipelines are open and independent of proprietary Cloud platform runtimes. Across all migrated jobs (from a few thousand to more than 50 million rows), execution times are often counted in seconds, with an almost systematic OK status.

Screenshot: Benefits – from legacy ETL to an open SQL ETL - {oa-tbx}

Governance and data lineage

{oa-tbx} keeps the complete trace between the original ETL logic and the executed SQL, at two levels of detail.

High-level pipeline view: only source and target tables are visible; intermediate ETL stages are grouped into a single SQL block, readable even for complex pipelines.

Screenshot: Governance and data lineage – from legacy ETL to an open SQL ETL - {oa-tbx}

Detail on click for a transformation: clicking a stage (a Transformer, for example) displays its SQL equivalent, along with its inputs/outputs and its original metadata (type, stage ID).

Screenshot: Governance and data lineage – from legacy ETL to an open SQL ETL - {oa-tbx}

Result: a SQL-based ETL/ELT chain, open and version-controllable, governed from the overview down to the executed SQL, regardless of the original ETL platform.

Frequently asked questions

Where do ETL processes run once converted to SQL?
In {oa-tbx}, an execution container for SQL, Python or Java processes, driven by configuration and orchestration repositories. Processes run independently of the original ETL platform.
Who handles orchestration of the migrated processes?
The workflow layer, kept separate from the processes: Airflow, or a tool such as Dagster. It manages dependencies, execution parameters, schedules and triggers. Scheduling for an ETL migrated to Airflow automatically carries over the original instructions and sequencing.
Which sources and targets can {oa-tbx} handle?
As input, any technology accessible through SQL or JDBC; as output, any system compatible with standard write mechanisms. {oa-tbx} can also use an embedded database, DuckDB, for some intermediate processing.
What performance can be expected after migrating to {oa-tbx}?
Across all migrated jobs, with volumes ranging from a few thousand to more than 50 million rows, execution times are often just a few seconds, with an almost systematic OK status.
Is the link between the original ETL and the executed SQL preserved?
Yes. {oa-tbx} keeps the full trace: a high-level view of the pipeline (source and target tables) and, on clicking a stage, the generated SQL with its inputs, outputs and original metadata (type, stage ID).
Équipe Ellipsys
Authors
{openAudit} | Data Lineage & Migration
Ingénieurs IT spécialisés en data lineage technique, migration BI/ETL et architectures SQL ouvertes.