DiunDashboard/.planning/phases/03-postgresql-support/03-01-SUMMARY.md

phase, plan, subsystem, tags, dependency_graph, tech_stack, key_files, decisions, metrics

phase	plan	subsystem	tags	dependency_graph	tech_stack	key_files	decisions	metrics
03-postgresql-support	01	persistence	postgresql store migration pgx	requires provides affects PostgresStore RunPostgresMigrations RunSQLiteMigrations pkg/diunwebhook/migrate.go pkg/diunwebhook/postgres_store.go	added patterns github.com/jackc/pgx/v5 v5.9.1 golang-migrate pgx/v5 driver Store interface implementation golang-migrate embedded migrations pgx/v5 stdlib adapter	created modified pkg/diunwebhook/postgres_store.go pkg/diunwebhook/migrations/postgres/0001_initial_schema.up.sql pkg/diunwebhook/migrations/postgres/0001_initial_schema.down.sql pkg/diunwebhook/migrate.go pkg/diunwebhook/export_test.go go.mod go.sum	PostgresStore uses *sql.DB via pgx/v5/stdlib adapter — no native pgx pool, consistent with SQLiteStore pattern No mutex in PostgresStore — PostgreSQL handles concurrent writes natively (unlike SQLite) Timestamps stored as TEXT in PostgreSQL schema — matches SQLite scan logic, avoids TIMESTAMPTZ type divergence CreateTag uses RETURNING id instead of LastInsertId — pgx driver does not support LastInsertId AssignTag uses ON CONFLICT (image) DO UPDATE instead of INSERT OR REPLACE — standard PostgreSQL upsert Both migration runners compiled into same binary — no build tags needed (both drivers always present)	duration completed tasks_completed files_changed ~2.5 minutes 2026-03-24T08:09:42Z 2 7

Phase 03 Plan 01: PostgreSQL Store and Migration Infrastructure Summary

PostgresStore implementing all 9 Store interface methods using pgx/v5 stdlib adapter, plus PostgreSQL migration infrastructure with RunPostgresMigrations and renamed RunSQLiteMigrations.

What Was Built

PostgresStore (pkg/diunwebhook/postgres_store.go)

Full implementation of the Store interface for PostgreSQL:

• NewPostgresStore constructor with connection pool: MaxOpenConns(25), MaxIdleConns(5), ConnMaxLifetime(5m)
• All 9 methods: UpsertEvent, GetUpdates, AcknowledgeUpdate, ListTags, CreateTag, DeleteTag, AssignTag, UnassignTag, TagExists
• PostgreSQL-native SQL: $1..$15 positional params, NOW(), RETURNING id, ON CONFLICT DO UPDATE
• No sync.Mutex — PostgreSQL handles concurrent writes natively

PostgreSQL Migrations (pkg/diunwebhook/migrations/postgres/)

• 0001_initial_schema.up.sql: Creates same 3 tables as SQLite (updates, tags, tag_assignments); uses SERIAL PRIMARY KEY for tags.id; timestamps remain TEXT to match scan logic
• 0001_initial_schema.down.sql: Drops all 3 tables in dependency order

Updated migrate.go

• RunMigrations renamed to RunSQLiteMigrations
• RunPostgresMigrations added using pgxmigrate driver with "pgx5" database name
• Second //go:embed migrations/postgres directive added for postgresMigrations

Decisions Made

Decision	Rationale
TEXT timestamps in PostgreSQL schema	Avoids scan divergence with SQLiteStore; both stores parse RFC3339 strings identically
RETURNING id in CreateTag	pgx driver does not implement LastInsertId; RETURNING is the PostgreSQL-idiomatic approach
ON CONFLICT (image) DO UPDATE in AssignTag	Replaces SQLite's INSERT OR REPLACE; functionally equivalent upsert in standard SQL
No mutex in PostgresStore	PostgreSQL connection pool + MVCC handles concurrency; mutex would serialize unnecessarily
Both drivers compiled into binary	Simpler than build tags; binary size cost acceptable for a server binary

Deviations from Plan

Auto-fixed Issues

1. [Rule 1 - Bug] Updated export_test.go to use renamed function

• Found during: Task 1 verification
• Issue: go vet ./pkg/diunwebhook/ failed because export_test.go still referenced RunMigrations (renamed to RunSQLiteMigrations). The plan's acceptance criteria requires go vet to exit 0, which takes precedence over the instruction to defer export_test.go changes to Plan 02.
• Fix: Updated both NewTestServer and NewTestServerWithSecret in export_test.go to call RunSQLiteMigrations
• Files modified: pkg/diunwebhook/export_test.go
• Commit: 95b64b4

Verification Results

• go build ./pkg/diunwebhook/ exits 0
• go vet ./pkg/diunwebhook/ exits 0
• PostgreSQL migration UP contains SERIAL PRIMARY KEY, all 3 tables
• PostgreSQL migration DOWN contains DROP TABLE IF EXISTS for all 3 tables
• go.mod contains github.com/jackc/pgx/v5 v5.9.1
• migrate.go exports both RunSQLiteMigrations and RunPostgresMigrations

Known Stubs

None — this plan creates implementation code, not UI stubs.

Self-Check: PASSED