Computed Join Introduction

A Computed Join combines data from two containers (in the same datastore or across datastores) into a single, queryable result that you can profile and run quality checks against. Use it when the join needs governance and observability rather than a one-off SQL view.

What It Does

A Computed Join takes two existing containers (a left and a right) and joins them on a field from each side. The two fields can have different names but must be the same data type. The two inputs can live in the same datastore or in different datastores. Qualytics loads each side and computes the join for you, so the source systems don't see a cross-datastore query.

You configure the result by choosing the join type (Inner, Left, Right, or Full Outer), selecting which columns to project, and optionally filtering or aggregating the joined data.

The join itself is not stored. Each profile or scan re-loads both sides and computes the joined result, which keeps the output in sync with the underlying containers without you having to refresh it.

A single Computed Join always combines exactly two inputs. For three-way joins or more, express the first join inside a Computed Table and use that Computed Table as one side of the next Computed Join.

Why It Matters

• Cross-datastore analytics. Combine a JDBC table with a DFS file (or any other mix) into one queryable result, without setting up a federated view at the source.
• Reusable transformation logic. Express filters and aggregations once at the join level, then run quality checks against the joined output.
• Quality checks on derived data. A Computed Join behaves like a regular container. You can profile it, run checks against it, and detect anomalies on the joined result.

Where It Fits

The joined output is a real container in Qualytics. It appears under the left input's datastore, has its own profile, and supports the same observability features (volumetric tracking, freshness checks). You can run scans and quality checks against it like any other container. Sync does not apply to a Computed Join: Sync discovers containers in the source system, and the Computed Join is produced by Qualytics rather than discovered.

Next Steps