Multi-Table Metadata Extraction
Table Metadata
Overview
This page documents the attributes extracted for each table during database metadata analysis.
Table metadata includes information about a table’s columns, keys, and relationships to other tables (especially its relationship to the subject table).
Subject table
The subject table is the core table whose rows represent the “subjects” of privacy protection.
For non-subject tables, privacy accounting and downstream workflows can depend on how many subject records can be linked (directly or indirectly) to a row in that table.
Table attributes
| Attribute | Description |
|---|---|
| Table name | The table name as defined in the database. |
| Columns metadata | Metadata for the columns selected for analysis. See Column Metadata. |
| Is private | Whether the table is marked as private. |
| Is selected | Whether the table is included in extraction and downstream workflows (for example, UI display and generation). |
| Foreign keys | The foreign key relationships defined (or inferred) for the table. |
| Primary key | The column(s) that make up the primary key. |
| Unique keys | The unique key definitions for the table. Each unique key is a list of one or more columns. |
| Row count | The number of rows in the table. |
| Max subject references | The maximum number of subject-table records that can be linked to a record in this table (based on the discovered relationships). |
Foreign key attributes
Each table can have zero or more foreign keys. For each foreign key relationship, AGENT tracks both the relationship endpoints (table/column) and relationship statistics that are useful for understanding join cardinality and downstream generation.
| Attribute | Description |
|---|---|
| Column name | The column in the current table that participates in the foreign key relationship. |
| Ref table name | The referenced table. |
| Ref column name | The referenced column in the referenced table. |
| Min references | The minimum number of references to the referenced table for a single value. |
| Max references | The maximum number of references to the referenced table for a single value. |
| Max ref column frequency | The maximum frequency observed for values in the referenced column. |
| Selected | Whether this foreign key is selected. If false, it is not shown in the UI and is not used for data generation. |
| Is auto generated | Whether the foreign key was derived automatically from database metadata or created by a user. |
| Auto-gen min references | Minimum references inferred from database metadata. |
| Auto-gen max references | Maximum references inferred from database metadata. |
Differential privacy
Most of the attributes above can be calculated using differentially private results.
To learn more about how we implement Subject Level Differential Privacy, see Subject Level Privacy