Product area
Catalog
Unity Catalog: metastore, catalogs, schemas, managed and external tables, privileges, row filters, column masks, ABAC, lineage.
Concepts
- 1Unity Catalog, the governance layerUnity Catalog is the governance system of Databricks: a single catalog that knows which tables, volumes, functions, and models exist, where their files live, who can do what, and where the data comes from. It lives at the account level, not the workspace…Beginner
- 2The metastore and how a workspace gets Unity CatalogThe metastore is the top-level container in Unity Catalog. It holds the catalogs, and through them every schema, table, view, volume, function and model you govern. It also holds the objects that sit outside the catalog hierarchy: storage credentials…Beginner
- 3Managed and external tablesA table in Unity Catalog has two components: the metadata (name, schema, permissions, statistics) and the files in object storage. The distinction between managed and external is about who controls the files.Intermediate
- 4External locations and storage credentialsTwo securable objects sit directly under the metastore, and together they are the only sanctioned route from Databricks to a cloud bucket.Intermediate
- 5Privileges: GRANT, REVOKE, and DENYA privilege is the right to perform an action on a securable (catalog, schema, table, view, volume, function, model, external location, and so on). You assign it to a principal: a user, a group, or a service principal. In Unity Catalog the model is easy to…Intermediate
- 6Row filters and column masksWith GRANT SELECT a user sees either the whole table or nothing. Row filters and column masks add a layer below that: the same table, with the same SELECT, returns different rows and values to different users.Advanced
- 7ABAC policies in Unity CatalogABAC (attribute-based access control) is how Unity Catalog applies access rules based on the attributes of objects rather than their names. The attribute is a governed tag (pii = email, sensitivity = high); the rule is a policy attached to a catalog, a…Advanced
- 8Data lineage in Unity CatalogLineage is the record of which object produced which other object. Unity Catalog builds it for you: every time a query reads or writes a governed table, view, volume, model or function, the metastore records the edge, down to the column level. There is…Intermediate
- 9System tablesSystem tables are read-only, Databricks-hosted tables in a catalog called system that record how your account is actually used: what it costs, which jobs ran and how they ended, who read which table, which clusters existed, which statements executed. You…Intermediate
- 10Lakehouse FederationLakehouse Federation lets you query data that lives in another system as if it were a catalog in your metastore. You register a connection holding the location and credentials of the external system, create a foreign catalog from that connection, and its…Intermediate
- 11Workspace-catalog bindingA catalog does not belong to a workspace. It belongs to the metastore, and by default every workspace attached to that metastore can see it and query it (see uc metastore and setup). Workspace-catalog binding overrides that default: you switch the catalog's…Intermediate
- 12Managed and external volumesA volume is a Unity Catalog object that governs files. It sits under a schema alongside tables, views and functions, so its full name is catalog.schema.volume, and it is the third level of the namespace even though you address its contents by path rather than…Intermediate
- 13The information schemainformationschema is the SQL standard set of metadata views, and Unity Catalog gives you two of them.Intermediate
- 14Governed tagsA tag in Unity Catalog is a key with an optional value stuck onto an object. By default tags are free-form: anyone with APPLY TAG on the object, plus USE SCHEMA and USE CATALOG above it, can invent the key, invent the value and attach it. That is fine for…Intermediate
- 15Data Classification in Unity CatalogData Classification is a Unity Catalog feature that looks inside your tables, works out which columns hold sensitive values, and tags those columns with system governed tags from the class. family: class.emailaddress, class.usssn, class.phonenumber…Intermediate
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