Set Up the Database
Momen provides a PostgreSQL-backed relational database. Open the Data tab → Data model to configure tables, fields, relations, constraints, and permissions.
Conceptual background: Relational Data Modeling. Vector search: Set Up Vector Search.
Data model
Add table
Each project includes system tables (e.g. account, payment). System tables cannot be deleted. Among system tables, only the account table supports adding custom fields.
Properties:
- Name — avoid reserved words like
log,column,index - Description — optional
- Turn on permissions for all roles — grant table CRUD to all roles
Add fields
Every table includes id, created_at, and updated_at (system-managed, not editable).
- Name — avoid reserved words like
column - Type — see Data Types
- Required, Unique, Turn on permissions for all roles
Momen uses Decimal for precise numbers. Custom code (JavaScript) or float APIs can introduce precision loss (e.g. 0.1 + 0.2 → 0.30000000000000004) if written back to the database.
Add relations
Tables link via id. Example: account ↔ posts (author).
When creating a relation, set:
- Target table
- Relation type — one-to-one or one-to-many (many-to-many via junction table — see Relational Data Modeling · Many-to-many)
- Relation names on each side
- Turn on permissions for all roles
For many-to-many: create a junction table; both sides link one-to-many to it.
Sync changes
Sync changes so the data model takes effect online.
On live apps, schema changes can break in-flight requests. Proceed carefully.
Constraint settings
Unique constraints prevent duplicate values on one or more columns.
Open constraint settings
Table menu → Edit Constraints.
Add constraint
Each table has a default id uniqueness constraint.
- Constraint name — unique, lowercase
- Column set — single or combined uniqueness
- Storage limit — combined row data in constrained columns ≤ 8,191 bytes (UTF-8 encoding affects character count)
Example: unique combination of title + user_account per author.
Sync changes
- Existing violating data blocks sync
- After sync, constraints cannot be edited — delete a column in the set to remove
- Sync again after changes
Permission management
Momen combines RBAC and ABAC for data security. See Permissions.