Is Snowflake Horizon Catalog really a single pane of glass if access policies do not transfer to other catalogs?
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No Catalog's Access Policies Cross Into the Other's
Neither vendor has solved cross-catalog policy propagation. The marketing claim and the engineering reality come from the same company.
Snowflake's article calls Horizon Catalog a single pane of glass for managing access policies across engines. Snowflake's own engineering blog says the opposite: policies from one catalog do not automatically carry into the other, on either platform. This is not a Databricks gap. Snowflake's own catalog works exactly the same way.
What "single pane of glass" would require
Not a dashboard that shows both platforms. A policy defined once, in one catalog, enforced automatically the moment a table crosses into the other platform's compute, no re-declaration required. That is the bar the phrase implies. Databricks does not clear it, and neither does Snowflake, whatever its own marketing implies.
| Capability | Databricks | Snowflake |
|---|---|---|
| Policies defined in Unity Catalog, enforced automatically from Snowflake | Not supported | Not supported |
| Policies defined in Snowflake, enforced automatically from Databricks | Not supported | Not supported |
| Access control / lineage scope | Per metastore, one per region, does not cross region or platform | Does not sync remote catalog access control for users or roles |
| Vendor's own dual-platform guidance | Not published | "Use Horizon for Snowflake-originated data and Unity Catalog for Databricks-originated data" |
What shipped, and when
Snowflake's own engineering post, published May 21, 2026, states plainly that fine-grained policies from the remote catalog do not automatically carry over, each platform enforces its own policies on its own compute, and recommends dual-platform organizations use Horizon for Snowflake-originated data and Unity Catalog for Databricks-originated data. Snowflake's catalog-linked database documentation adds that Snowflake does not sync remote catalog access control for users or roles.
Unity Catalog's own documentation scopes access control and lineage to the metastore, one per region, stating that lineage graphs and access control "do not cross region or platform boundaries." Cross-region sharing runs through Databricks-to-Databricks OpenSharing, a separate mechanism, not a policy that travels with the table.
Where this sits
Not a concession, a parity finding. Databricks has not solved cross-catalog policy propagation. Snowflake has not either, its own engineering team says as much, in writing, a month before its marketing post implied otherwise.
The limits of this argument
This does not claim Unity Catalog has cross-region or cross-platform governance either. It does not claim OpenSharing solves the same problem Horizon claims to solve. It is a different mechanism, for a different scenario.
The verdict
A single pane of glass that only shows what is already on your own platform is not a single pane of glass. It is the same dual-catalog reality Databricks operates under, described by Snowflake's own engineers a month before Snowflake's marketing team described it differently.
Sources
[1] Snowflake, "Iceberg Catalog: Snowflake Horizon vs. Unity Catalog," May 21, 2026. https://www.snowflake.com/en/blog/engineering/iceberg-catalog-snowflake-horizon-vs-unity-catalog/
[2] Snowflake, "Catalog-linked databases." https://docs.snowflake.com/en/user-guide/tables-iceberg-catalog-linked-database
[3] Databricks, "Unity Catalog best practices." https://docs.databricks.com/aws/en/data-governance/unity-catalog/best-practices