feat: Add task state migration from MongoDB to PostgreSQL#128
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feat: Add task state migration from MongoDB to PostgreSQL#128
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Implement phased migration strategy for task states: - Phase 0: Add feature flag TASK_STATE_STORAGE_PHASE - Add TaskStateORM model and Alembic migration - Create TaskStatePostgresRepository for PostgreSQL storage - Create TaskStateDualRepository for phased rollout Migration phases supported: - mongodb: Legacy behavior (MongoDB only) - dual_write: Write to both, read from MongoDB - dual_read: Write to both, read from both with verification - postgres: PostgreSQL only (target state) Includes: - Datadog StatsD metrics for dual_read verification - Backfill script for existing MongoDB data - Verification script for data consistency checks - Unit tests for all repository operations and metrics
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- Add benchmark scripts for comparing MongoDB vs PostgreSQL performance: - benchmark_task_state.py: Repository-level benchmarks - benchmark_api.py: API-level benchmarks with connection pooling - compare_results.py: Generate markdown comparison reports - locustfile.py: Cluster load tests with Locust - Add storage_backend query parameter to dynamically switch backends: - Enables benchmarking without server restarts - Valid values: mongodb, dual_write, dual_read, postgres - Fix FastAPI dependency injection in TaskStateDualRepository: - Remove 'from __future__ import annotations' which broke DI resolution - Use List from typing to avoid 'list' method name shadowing - Update authorization_shortcuts to use DTaskStateDualRepository Benchmark results show MongoDB ~20-30% faster than PostgreSQL at API level.
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Summary
Implements a phased migration strategy for task state storage from MongoDB to PostgreSQL with zero-downtime rollout capability.
Key changes:
TASK_STATE_STORAGE_PHASEfeature flag to control migration phasestask_statesPostgreSQL table with JSONB state columnMigration Phases
mongodbdual_writedual_readpostgresFiles Changed
Core Implementation
src/adapters/orm.py- AddedTaskStateORMmodelsrc/config/environment_variables.py- AddedTASK_STATE_STORAGE_PHASEenv varsrc/domain/repositories/task_state_postgres_repository.py- PostgreSQL repository (new)src/domain/repositories/task_state_dual_repository.py- Dual-write wrapper (new)src/domain/use_cases/states_use_case.py- Updated to use dual repositoryDatabase Migration
database/migrations/alembic/versions/2026_01_12_0000_add_task_states_table_*.py- Alembic migrationScripts
scripts/backfill_task_states.py- Backfill existing MongoDB data to PostgreSQLscripts/verify_task_states.py- Verify data consistency between databasesTests
tests/unit/repositories/test_task_state_postgres_repository.py- 2 teststests/unit/repositories/test_task_state_dual_repository.py- 35 testsMetrics (dual_read phase)
task_state.dual_read.matchtask_state.dual_read.mismatch.missing_postgrestask_state.dual_read.mismatch.missing_mongodbtask_state.dual_read.mismatch.state_contenttask_state.dual_read.list_count_mismatchRollout Plan
TASK_STATE_STORAGE_PHASE=mongodb(no behavior change)python scripts/backfill_task_states.pyTASK_STATE_STORAGE_PHASE=dual_writeTASK_STATE_STORAGE_PHASE=dual_read, monitor metricsTASK_STATE_STORAGE_PHASE=postgresRollback
Set
TASK_STATE_STORAGE_PHASEback to the previous phase at any time.Test plan