---
title: migration_service | CodeWeaver Docs
description: API reference for codeweaver.engine.services.migration_service
url: "https://docs.knitli.com/api/engine/services/migration_service"
type: static
generatedAt: "2026-04-17T17:21:08.584Z"
---

# migration_service
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# `codeweaver.engine.services.migration_service`
[Section titled “codeweaver.engine.services.migration_service”](#codeweaverengineservicesmigration_service)
Migration service for vector store transformations.

This service implements dimension reduction and quantization migrations with:

 - CRITICAL #3: Parallel processing with worker pools
 - CRITICAL #4: Data integrity validation (4 layers)
 - CRITICAL #5: Resume capability with checkpoints

ARCHITECTURE: Plain class with no DI in constructor (factory handles DI).

## Class: `ChunkResult`
[Section titled “Class: ChunkResult”](#class-chunkresult)
Result from migrating a chunk.

## Class: `InvalidStateTransitionError`
[Section titled “Class: InvalidStateTransitionError”](#class-invalidstatetransitionerror)
Invalid state transition attempted.

## Class: `MigrationCheckpoint`
[Section titled “Class: MigrationCheckpoint”](#class-migrationcheckpoint)
Persistent checkpoint for migration state.

## Class: `MigrationError`
[Section titled “Class: MigrationError”](#class-migrationerror)
Base exception for migration errors.

## Class: `MigrationResult`
[Section titled “Class: MigrationResult”](#class-migrationresult)
Results of migration operation.

## Class: `MigrationService`
[Section titled “Class: MigrationService”](#class-migrationservice)
Comprehensive migration service with parallel workers.

ARCHITECTURE NOTE: This is a PLAIN CLASS with no DI in constructor. Factory function in engine/dependencies.py handles DI integration.

Implements:

 - CRITICAL #3: Parallel processing with worker pool
 - CRITICAL #4: Data integrity validation (4 layers)
 - CRITICAL #5: Resume capability with checkpoints

### Method: `migrate_dimensions_parallel`
[Section titled “Method: migrate_dimensions_parallel”](#method-migrate_dimensions_parallel)

**

```
migrate_dimensions_parallel()
```

Main entry point for parallel dimension migration.

Implements CRITICAL #3 (parallel processing), CRITICAL #4 (data integrity), and CRITICAL #5 (resume capability).

Args: new_dimension: Target dimension for migration worker_count: Number of parallel workers (default: 4) batch_size: Vectors per batch (default: 1000) resume: Whether to resume from checkpoint (default: True)

Returns: MigrationResult with timing and statistics

Raises: ValidationError: Data integrity validation failed MigrationError: Migration operation failed

## Class: `MigrationState`
[Section titled “Class: MigrationState”](#class-migrationstate)
Migration state machine states.

State Transitions: PENDING -> IN_PROGRESS -> COMPLETED -> ROLLBACK -> PENDING ↓ FAILED -> PENDING

## Class: `ValidationError`
[Section titled “Class: ValidationError”](#class-validationerror)
Data integrity validation failed.

## Class: `WorkItem`
[Section titled “Class: WorkItem”](#class-workitem)
Work item for parallel migration.