Every organisation with competent engineers considers building its own catalog, and the reasoning is sound at the point it is made. A catalog reads database schemas and stores them somewhere searchable. A good engineer produces a working version in a fortnight. Commercial products are expensive and full of features you did not ask for.
The reasoning holds for exactly as long as the requirement is "somewhere to look up table names". It stops holding at the four capabilities that turn a metadata store into a governance platform, and each of those is a multi-quarter engineering project on its own.
This article is about deciding honestly, including the cases where building is the right answer.
What the first version costs, and why that number misleads
Two weeks of one engineer produces something real: a connector to your main database, harvested table and column metadata, a search interface, a place to write descriptions. It works, people are pleased, and it is genuinely useful.
The number misleads because the first version is the cheapest 10% of the problem. The remaining 90% is not more of the same work — it is four different problems, none of which resembles the first two weeks.
The four capabilities that decide it
Column-level lineage. Not table-level — column-level, parsed from SQL, stored procedures and ETL definitions. This means writing or integrating a SQL parser that handles your actual dialects, resolves views, follows temporary tables through stored procedures, and copes with dynamic SQL. This is not a feature; it is a specialist product category, and it is where every build project underestimates by a factor of several. If your requirement is only table-level lineage, building is far more feasible — and you should be honest about whether that satisfies your auditor. It usually does not; see data lineage explained.
Connector breadth and maintenance. Your first three connectors are straightforward. The twentieth is a mainframe extract with a fixed-width layout and no metadata at all. Then every source system upgrades on its own schedule, and each upgrade is a maintenance event you now own. Commercial products carry this cost across their whole customer base; you carry it alone.
Access control and workflow. Fine-grained permissions on metadata, access-request workflow, approval routing, and audit of who saw what. This is ordinary enterprise software work, and it is a substantial amount of it — and in a supervised institution it cannot be skipped, because the metadata repository is itself sensitive.
Adoption features. Search that actually finds things, usage signals, inline definitions in the query editor, change notifications to downstream owners. This is the difference between a catalog people consult and one they encounter, and it is where the return on the whole programme actually comes from. It is also the part of a build that never gets prioritised, because it always looks less urgent than another connector.
If you need all four, building is a product development programme rather than an internal tool. Be explicit about that when the decision is made, not eighteen months later.
The honest three-year comparison
Buying costs licence plus implementation plus a fraction of an engineer for platform operation. Implementation for a scoped domain is measured in weeks with a value platform and in quarters with an enterprise suite.
Building costs two to four engineers continuously — not for a project, but permanently, because a catalog is a live system with connectors that break when sources upgrade. Add the opportunity cost of what those engineers would otherwise deliver, and the key-person risk: the catalog becomes the property of whoever wrote it, and their departure converts an asset into a liability.
The comparison usually favours buying, and the margin is wider than it appears at the outset because the build case is almost always priced as a project rather than as a product with an indefinite maintenance obligation.
There is a third path worth naming: open-source foundations. Projects like DataHub, OpenMetadata and Amundsen give you a substantial head start on the storage, model and interface layers. This is genuinely cheaper than building from nothing. It is not free — you own deployment, upgrades, connector gaps, security integration and the adoption features — and it is best understood as buying the first 40% and building the rest.
When building is right
Two cases, and they are real.
Your requirements are genuinely narrow and stable. You need searchable technical metadata for six systems, table-level lineage is sufficient, you have no regulatory lineage obligation, and you have engineers with spare capacity. Build it. A commercial catalog for this requirement is overspending, and the maintenance burden is small because the scope is small.
You have a requirement no product meets. A proprietary system nobody supports, an unusual security model, an integration into an internal platform that is central to how your organisation works. Then you build — but build only the part that is genuinely unmet, and integrate rather than reimplement everything around it.
What is not a good reason: "we can do it cheaper." That is true of the first version and false of the third year, and the difference is where the decision actually lives.
The build decision in a regulated Azerbaijani institution
Three local factors shift the balance, two toward buying and one toward building.
Toward buying: the lineage obligation. A supervisor asking how a submitted figure was calculated needs column-level lineage, harvested rather than drawn. Building a SQL parser that handles your Oracle dialect, your stored procedures and your legacy ETL is the single largest engineering commitment in this whole decision, and it is the one that is hardest to abandon halfway.
Toward buying: the talent market. There are not many engineers in Azerbaijan who have built metadata infrastructure, and a system built by two exceptional people collapses when they leave. A commercial product with local implementation capability is a hedge against that, and it is a real one.
Toward building: the deployment constraint. If the products you can actually deploy on-premise do not meet your needs, building becomes more attractive by elimination. This is worth testing before concluding it — several catalogs deploy on-premise as a first-class product, and the field is narrower than the cloud market but not empty. The comparisons are in OvalEdge vs Collibra vs Alation and OvalEdge vs Atlan.
How to decide in two weeks
A short, cheap process that produces a defensible answer.
Write down the four capabilities and mark which you actually need. If column-level lineage and access workflow are both required, the answer is almost certainly buy, and you can stop.
Cost the build as a product, not a project. Three years, continuous staffing, connector maintenance, and the adoption features. Compare that to licence plus implementation plus a fraction of an engineer.
Run a two-week spike on the hardest part. Point an open-source catalog at your worst legacy source and try to get column-level lineage out of it. Whatever you learn in those two weeks is worth more than any amount of estimation, and it is usually decisive in one direction.
Then decide, and write down why. In eighteen months someone will ask, and the reasoning is more useful than the conclusion.
Key points
- The first version of a catalog is cheap and represents about 10% of the problem. The other 90% is four different problems.
- Column-level lineage parsed from your real SQL is the capability that breaks build projects. Table-level lineage is far more feasible and usually does not satisfy an auditor.
- Building costs two to four engineers permanently, not once. Price it as a product with an indefinite maintenance obligation.
- Open-source foundations are a legitimate third path — roughly buying the first 40% and building the rest.
- Build when requirements are narrow and stable, or when a genuine requirement is unmet by every deployable product.
- Decide with a two-week spike against your worst legacy source, not with a spreadsheet of estimates.
We implement OvalEdge on-premise, and the governance assessment maps the estate first — which usually makes this decision straightforward. Related reading: what is a data catalog and metadata management.