dimgigov
4a83eb6783
- Add multi-database limitations to distributed docs - Fix backup commands and add multi-database backup guidance - Add SQL migration section to schema docs - Update storage examples to use per-database paths
81 lines
1.6 KiB
Markdown
81 lines
1.6 KiB
Markdown
# Schema System
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BaraDB uses a schema-first design with type inheritance and automatic migrations.
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## Defining Types
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```nim
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import barabadb/schema/schema
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var s = newSchema()
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let person = newType("Person")
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person.addProperty("name", "str", required = true)
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person.addProperty("age", "int32")
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s.addType("default", person)
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```
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## Type Inheritance
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```nim
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let employee = newType("Employee")
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employee.setBases(@["Person"])
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employee.addProperty("department", "str")
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s.addType("default", employee)
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# Resolve inheritance — Employee gets name, age, department
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let resolved = s.resolveInheritance(employee)
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```
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## Schema Operations
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### Diff
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Compare two schemas:
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```nim
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let diff = s.diff(oldSchema, newSchema)
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```
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### Migrations
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Schema changes are tracked and can generate migration scripts.
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## SQL Migrations
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BaraDB supports SQL-level migrations executed through BaraQL:
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```sql
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-- Create a migration table
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CREATE MIGRATION TABLE my_migration;
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-- Apply pending migrations
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MIGRATION UP;
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-- Rollback last migration
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MIGRATION DOWN;
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-- Apply all pending migrations in batch
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MIGRATION UP BATCH;
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-- Dry-run to preview changes
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MIGRATION DRYRUN;
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-- Check migration status
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MIGRATION STATUS;
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```
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Migration scripts are stored inside each database's LSMTree and are isolated per database. When using multiple databases, run `USE DATABASE <name>` before executing migration commands.
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## Property Types
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| Type | Description |
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|------|-------------|
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| `str` | String |
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| `int32` | 32-bit integer |
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| `int64` | 64-bit integer |
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| `float32` | 32-bit float |
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| `float64` | 64-bit float |
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| `bool` | Boolean |
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| `datetime` | Date/time value |
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| `bytes` | Binary data | |