26 KiB
Thoughts v2 — Plan 2: Full-Text Search (postgres-search)
For agentic workers: REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (
- [ ]) syntax for tracking.
Goal: Upgrade search from a full-table-scan ILIKE to indexed trigram search (pg_trgm), returning both thoughts and users from a single /search endpoint.
Architecture: A new SearchPort trait in domain defines cross-entity search (thoughts + users). crates/adapters/postgres-search implements it using pg_trgm similarity with GIN indexes. The existing FeedRepository::search in postgres/feed.rs is also upgraded to use the % trigram operator so it benefits from the new index. Presentation adds search: Arc<dyn SearchPort> to AppState.
Tech Stack: Rust, sqlx 0.8, PostgreSQL pg_trgm extension, GIN indexes, axum
File Map
Modified: crates/domain/src/ports.rs ← add SearchPort trait
Modified: crates/domain/src/testing.rs ← add TestStore impl for SearchPort
Modified: crates/adapters/postgres-search/Cargo.toml ← add deps
Modified: crates/adapters/postgres-search/src/lib.rs ← PgSearchRepository (was empty stub)
Create: crates/adapters/postgres/migrations/004_search_indexes.sql
Modified: crates/adapters/postgres/src/feed.rs ← upgrade ILIKE → trigram operator
Modified: crates/presentation/src/state.rs ← add search field
Modified: crates/presentation/src/lib.rs ← wire PgSearchRepository in build_state
Modified: crates/presentation/src/handlers/feed.rs ← search_handler returns thoughts + users
Task 1: Migration — pg_trgm extension and GIN indexes
Files:
-
Create:
crates/adapters/postgres/migrations/004_search_indexes.sql -
Write
004_search_indexes.sql:
CREATE EXTENSION IF NOT EXISTS pg_trgm;
CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_thoughts_content_trgm
ON thoughts USING GIN(content gin_trgm_ops);
CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_users_username_trgm
ON users USING GIN(username gin_trgm_ops);
CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_users_display_name_trgm
ON users USING GIN(display_name gin_trgm_ops)
WHERE display_name IS NOT NULL;
- Apply migration to test DB:
DATABASE_URL=postgres://postgres:postgres@localhost:5434/postgres \
cargo sqlx migrate run --source crates/adapters/postgres/migrations
Expected: Applied 1/migrate search indexes
- Verify pg_trgm works:
psql postgres://postgres:postgres@localhost:5434/postgres \
-c "SELECT similarity('hello world', 'hello');"
Expected: a float value like 0.5 (not an error).
- Commit:
git add crates/adapters/postgres/migrations/004_search_indexes.sql
git commit -m "feat(postgres): pg_trgm extension and GIN search indexes"
Task 2: Domain — SearchPort trait and TestStore implementation
Files:
-
Modify:
crates/domain/src/ports.rs -
Modify:
crates/domain/src/testing.rs -
Write failing test — add to bottom of
crates/domain/src/testing.rs(inside#[cfg(any(test, feature = "test-helpers"))]):
#[cfg(test)]
mod search_tests {
use super::*;
use crate::models::feed::PageParams;
#[tokio::test]
async fn test_store_search_thoughts_returns_empty() {
let store = TestStore::default();
let result = store.search_thoughts("hello", &PageParams { page: 1, per_page: 20 }, None).await.unwrap();
assert_eq!(result.total, 0);
}
#[tokio::test]
async fn test_store_search_users_returns_empty() {
let store = TestStore::default();
let result = store.search_users("alice", &PageParams { page: 1, per_page: 20 }).await.unwrap();
assert_eq!(result.total, 0);
}
}
-
Run:
cargo test -p domain— Expected: FAIL (SearchPort not defined yet). -
Add
SearchPorttocrates/domain/src/ports.rs— append after theFeedRepositorytrait:
#[async_trait]
pub trait SearchPort: Send + Sync {
/// Full-text search over public thoughts, ranked by trigram similarity.
async fn search_thoughts(
&self,
query: &str,
page: &PageParams,
viewer_id: Option<&UserId>,
) -> Result<Paginated<FeedEntry>, DomainError>;
/// Search users by username or display_name, ranked by trigram similarity.
async fn search_users(
&self,
query: &str,
page: &PageParams,
) -> Result<Paginated<User>, DomainError>;
}
- Add
TestStore impl SearchPortincrates/domain/src/testing.rs— append after theimpl FeedRepository for TestStoreblock:
#[async_trait] impl SearchPort for TestStore {
async fn search_thoughts(&self, _q: &str, _p: &PageParams, _v: Option<&UserId>) -> Result<Paginated<FeedEntry>, DomainError> {
Ok(Paginated { items: vec![], total: 0, page: 1, per_page: 20 })
}
async fn search_users(&self, _q: &str, _p: &PageParams) -> Result<Paginated<User>, DomainError> {
Ok(Paginated { items: vec![], total: 0, page: 1, per_page: 20 })
}
}
-
Run:
cargo test -p domain— Expected: all tests PASS. -
Commit:
git add crates/domain/src/ports.rs crates/domain/src/testing.rs
git commit -m "feat(domain): SearchPort trait with thought and user search"
Task 3: postgres-search — PgSearchRepository
Files:
-
Modify:
crates/adapters/postgres-search/Cargo.toml -
Modify:
crates/adapters/postgres-search/src/lib.rs -
Write failing tests at bottom of
crates/adapters/postgres-search/src/lib.rs:
#[cfg(test)]
mod tests {
use super::*;
use domain::{
models::{thought::{Thought, Visibility}, user::User},
ports::{SearchPort, ThoughtRepository, UserRepository},
value_objects::*,
};
async fn seed_thought(pool: &sqlx::PgPool, username: &str, content: &str) -> (User, Thought) {
use postgres::{thought::PgThoughtRepository, user::PgUserRepository};
let urepo = PgUserRepository::new(pool.clone());
let trepo = PgThoughtRepository::new(pool.clone());
let u = User::new_local(
UserId::new(),
Username::new(username).unwrap(),
Email::new(format!("{username}@ex.com")).unwrap(),
PasswordHash("h".into()),
);
urepo.save(&u).await.unwrap();
let t = Thought::new_local(
ThoughtId::new(), u.id.clone(),
Content::new_local(content).unwrap(),
None, Visibility::Public, None, false,
);
trepo.save(&t).await.unwrap();
(u, t)
}
#[sqlx::test(migrations = "../postgres/migrations")]
async fn search_thoughts_finds_by_keyword(pool: sqlx::PgPool) {
seed_thought(&pool, "alice", "hello world").await;
seed_thought(&pool, "bob", "goodbye universe").await;
let repo = PgSearchRepository::new(pool);
let result = repo.search_thoughts("hello", &domain::models::feed::PageParams { page: 1, per_page: 20 }, None).await.unwrap();
assert_eq!(result.total, 1);
assert_eq!(result.items[0].thought.content.as_str(), "hello world");
}
#[sqlx::test(migrations = "../postgres/migrations")]
async fn search_users_finds_by_username(pool: sqlx::PgPool) {
use postgres::user::PgUserRepository;
let urepo = PgUserRepository::new(pool.clone());
let alice = User::new_local(UserId::new(), Username::new("alice_search").unwrap(), Email::new("alice@ex.com").unwrap(), PasswordHash("h".into()));
urepo.save(&alice).await.unwrap();
let repo = PgSearchRepository::new(pool);
let result = repo.search_users("alice", &domain::models::feed::PageParams { page: 1, per_page: 20 }).await.unwrap();
assert!(!result.items.is_empty());
assert!(result.items.iter().any(|u| u.username.as_str() == "alice_search"));
}
#[sqlx::test(migrations = "../postgres/migrations")]
async fn search_thoughts_returns_empty_for_no_match(pool: sqlx::PgPool) {
seed_thought(&pool, "alice", "hello world").await;
let repo = PgSearchRepository::new(pool);
let result = repo.search_thoughts("zzzzzzzzz", &domain::models::feed::PageParams { page: 1, per_page: 20 }, None).await.unwrap();
assert_eq!(result.total, 0);
}
}
-
Run:
cargo test -p postgres-search— Expected: FAIL (PgSearchRepository not defined). -
Update
crates/adapters/postgres-search/Cargo.toml:
[package]
name = "postgres-search"
version = "0.1.0"
edition = "2021"
[dependencies]
domain = { workspace = true }
sqlx = { workspace = true }
uuid = { workspace = true }
chrono = { workspace = true }
async-trait = { workspace = true }
[dev-dependencies]
tokio = { workspace = true, features = ["full"] }
sqlx = { workspace = true, features = ["migrate"] }
postgres = { workspace = true }
Note: postgres in dev-dependencies is the internal crate at crates/adapters/postgres (already in workspace.dependencies). Add it to workspace.dependencies in root Cargo.toml if not already there:
# In root Cargo.toml [workspace.dependencies] — verify this line exists:
postgres = { path = "crates/adapters/postgres" }
- Write
crates/adapters/postgres-search/src/lib.rs:
use async_trait::async_trait;
use chrono::{DateTime, Utc};
use sqlx::PgPool;
use domain::{
errors::DomainError,
models::{
feed::{FeedEntry, PageParams, Paginated},
thought::Thought,
user::User,
},
ports::SearchPort,
value_objects::{Content, Email, PasswordHash, ThoughtId, UserId, Username},
};
use domain::models::thought::Visibility;
pub struct PgSearchRepository { pool: PgPool }
impl PgSearchRepository { pub fn new(pool: PgPool) -> Self { Self { pool } } }
// ── Feed row ─────────────────────────────────────────────────────────────────
#[derive(sqlx::FromRow)]
struct FeedRow {
thought_id: uuid::Uuid,
t_user_id: uuid::Uuid,
content: String,
in_reply_to_id: Option<uuid::Uuid>,
in_reply_to_url: Option<String>,
t_ap_id: Option<String>,
visibility: String,
content_warning: Option<String>,
sensitive: bool,
t_local: bool,
thought_created_at: DateTime<Utc>,
updated_at: Option<DateTime<Utc>>,
author_id: uuid::Uuid,
username: String,
email: String,
password_hash: String,
display_name: Option<String>,
bio: Option<String>,
avatar_url: Option<String>,
header_url: Option<String>,
custom_css: Option<String>,
author_local: bool,
u_ap_id: Option<String>,
inbox_url: Option<String>,
public_key: Option<String>,
private_key: Option<String>,
author_created_at: DateTime<Utc>,
author_updated_at: DateTime<Utc>,
like_count: i64,
boost_count: i64,
reply_count: i64,
}
const FEED_SELECT: &str = "
SELECT
t.id AS thought_id, t.user_id AS t_user_id, t.content,
t.in_reply_to_id, t.in_reply_to_url, t.ap_id AS t_ap_id,
t.visibility, t.content_warning, t.sensitive, t.local AS t_local,
t.created_at AS thought_created_at, t.updated_at,
u.id AS author_id, u.username, u.email, u.password_hash,
u.display_name, u.bio, u.avatar_url, u.header_url, u.custom_css,
u.local AS author_local, u.ap_id AS u_ap_id, u.inbox_url,
u.public_key, u.private_key,
u.created_at AS author_created_at, u.updated_at AS author_updated_at,
(SELECT COUNT(*) FROM likes l WHERE l.thought_id=t.id) AS like_count,
(SELECT COUNT(*) FROM boosts b WHERE b.thought_id=t.id) AS boost_count,
(SELECT COUNT(*) FROM thoughts r WHERE r.in_reply_to_id=t.id) AS reply_count
FROM thoughts t JOIN users u ON u.id=t.user_id";
fn row_to_entry(r: FeedRow) -> FeedEntry {
let thought = Thought {
id: ThoughtId::from_uuid(r.thought_id),
user_id: UserId::from_uuid(r.t_user_id),
content: Content::new_remote(r.content),
in_reply_to_id: r.in_reply_to_id.map(ThoughtId::from_uuid),
in_reply_to_url: r.in_reply_to_url,
ap_id: r.t_ap_id,
visibility: Visibility::from_str(&r.visibility),
content_warning: r.content_warning,
sensitive: r.sensitive,
local: r.t_local,
created_at: r.thought_created_at,
updated_at: r.updated_at,
};
let author = User {
id: UserId::from_uuid(r.author_id),
username: Username::from_trusted(r.username),
email: Email::from_trusted(r.email),
password_hash: PasswordHash(r.password_hash),
display_name: r.display_name, bio: r.bio,
avatar_url: r.avatar_url, header_url: r.header_url, custom_css: r.custom_css,
local: r.author_local, ap_id: r.u_ap_id, inbox_url: r.inbox_url,
public_key: r.public_key, private_key: r.private_key,
created_at: r.author_created_at, updated_at: r.author_updated_at,
};
FeedEntry { thought, author, like_count: r.like_count, boost_count: r.boost_count, reply_count: r.reply_count, liked_by_viewer: false, boosted_by_viewer: false }
}
// ── User row ──────────────────────────────────────────────────────────────────
#[derive(sqlx::FromRow)]
struct UserRow {
id: uuid::Uuid,
username: String,
email: String,
password_hash: String,
display_name: Option<String>,
bio: Option<String>,
avatar_url: Option<String>,
header_url: Option<String>,
custom_css: Option<String>,
local: bool,
ap_id: Option<String>,
inbox_url: Option<String>,
public_key: Option<String>,
private_key: Option<String>,
created_at: DateTime<Utc>,
updated_at: DateTime<Utc>,
}
impl From<UserRow> for User {
fn from(r: UserRow) -> Self {
User {
id: UserId::from_uuid(r.id),
username: Username::from_trusted(r.username),
email: Email::from_trusted(r.email),
password_hash: PasswordHash(r.password_hash),
display_name: r.display_name, bio: r.bio,
avatar_url: r.avatar_url, header_url: r.header_url, custom_css: r.custom_css,
local: r.local, ap_id: r.ap_id, inbox_url: r.inbox_url,
public_key: r.public_key, private_key: r.private_key,
created_at: r.created_at, updated_at: r.updated_at,
}
}
}
const USER_SELECT: &str =
"SELECT id,username,email,password_hash,display_name,bio,avatar_url,header_url,\
custom_css,local,ap_id,inbox_url,public_key,private_key,created_at,updated_at FROM users";
// ── SearchPort implementation ─────────────────────────────────────────────────
#[async_trait]
impl SearchPort for PgSearchRepository {
async fn search_thoughts(
&self,
query: &str,
page: &PageParams,
_viewer_id: Option<&UserId>,
) -> Result<Paginated<FeedEntry>, DomainError> {
// Use pg_trgm similarity operator — requires the GIN index from migration 004
let total: i64 = sqlx::query_scalar(
"SELECT COUNT(*) FROM thoughts t
WHERE t.content % $1 AND t.visibility='public'"
)
.bind(query)
.fetch_one(&self.pool)
.await
.map_err(|e| DomainError::Internal(e.to_string()))?;
let sql = format!(
"{FEED_SELECT}
WHERE t.content % $1 AND t.visibility='public'
ORDER BY similarity(t.content, $1) DESC
LIMIT $2 OFFSET $3"
);
let rows = sqlx::query_as::<_, FeedRow>(&sql)
.bind(query)
.bind(page.limit())
.bind(page.offset())
.fetch_all(&self.pool)
.await
.map_err(|e| DomainError::Internal(e.to_string()))?;
Ok(Paginated {
items: rows.into_iter().map(row_to_entry).collect(),
total,
page: page.page,
per_page: page.per_page,
})
}
async fn search_users(
&self,
query: &str,
page: &PageParams,
) -> Result<Paginated<User>, DomainError> {
let total: i64 = sqlx::query_scalar(
"SELECT COUNT(*) FROM users u
WHERE u.local=true AND (u.username % $1 OR u.display_name % $1)"
)
.bind(query)
.fetch_one(&self.pool)
.await
.map_err(|e| DomainError::Internal(e.to_string()))?;
let sql = format!(
"{USER_SELECT}
WHERE local=true AND (username % $1 OR display_name % $1)
ORDER BY similarity(username || ' ' || COALESCE(display_name,''), $1) DESC
LIMIT $2 OFFSET $3"
);
let rows = sqlx::query_as::<_, UserRow>(&sql)
.bind(query)
.bind(page.limit())
.bind(page.offset())
.fetch_all(&self.pool)
.await
.map_err(|e| DomainError::Internal(e.to_string()))?;
Ok(Paginated {
items: rows.into_iter().map(User::from).collect(),
total,
page: page.page,
per_page: page.per_page,
})
}
}
-
Run:
DATABASE_URL=postgres://postgres:postgres@localhost:5434/postgres cargo test -p postgres-searchExpected: 3 tests pass. -
Commit:
git add crates/adapters/postgres-search/
git commit -m "feat(postgres-search): PgSearchRepository using pg_trgm"
Task 4: Upgrade postgres ILIKE search to trigram operator
Files:
- Modify:
crates/adapters/postgres/src/feed.rs
The current FeedRepository::search uses ILIKE '%pattern%' which does a full table scan. Upgrade it to use the % trigram similarity operator which uses the GIN index from migration 004.
- Update the
searchmethod incrates/adapters/postgres/src/feed.rs:
Replace the entire search method (lines ~123-136) with:
async fn search(&self, query: &str, page: &PageParams, _viewer_id: Option<&UserId>) -> Result<Paginated<FeedEntry>, DomainError> {
let total: i64 = sqlx::query_scalar(
"SELECT COUNT(*) FROM thoughts t WHERE t.content % $1 AND t.visibility='public'"
)
.bind(query)
.fetch_one(&self.pool)
.await
.map_err(|e| DomainError::Internal(e.to_string()))?;
let sql = format!("{FEED_SELECT} WHERE t.content % $1 AND t.visibility='public' ORDER BY similarity(t.content, $1) DESC LIMIT $2 OFFSET $3");
let rows = sqlx::query_as::<_, FeedRow>(&sql)
.bind(query)
.bind(page.limit())
.bind(page.offset())
.fetch_all(&self.pool)
.await
.map_err(|e| DomainError::Internal(e.to_string()))?;
Ok(Paginated { items: rows.into_iter().map(row_to_entry).collect(), total, page: page.page, per_page: page.per_page })
}
Also update the existing search test in feed.rs — the ILIKE test uses "hello world" vs "hello". Trigram similarity works on substrings but with a minimum threshold. Update the test:
#[sqlx::test(migrations = "./migrations")]
async fn search_returns_matching_thoughts(pool: sqlx::PgPool) {
let (_, _) = seed(&pool, "alice", "hello world").await;
let (_, _) = seed(&pool, "bob", "goodbye world").await;
let repo = PgFeedRepository::new(pool);
// pg_trgm matches "hello" in "hello world" via trigram similarity
let result = repo.search("hello world", &PageParams { page: 1, per_page: 20 }, None).await.unwrap();
assert!(result.total >= 1);
assert!(result.items.iter().any(|e| e.thought.content.as_str() == "hello world"));
}
Note: use the full string "hello world" as query since single short words may fall below the default similarity threshold (0.3). Alternatively, adjust the threshold — but keeping the test realistic is better.
-
Run:
DATABASE_URL=postgres://postgres:postgres@localhost:5434/postgres cargo test -p postgresExpected: all tests pass. -
Commit:
git add crates/adapters/postgres/src/feed.rs
git commit -m "feat(postgres): upgrade search from ILIKE to pg_trgm similarity"
Task 5: Wire SearchPort into presentation
Files:
-
Modify:
crates/presentation/src/state.rs -
Modify:
crates/presentation/src/lib.rs -
Modify:
crates/presentation/src/handlers/feed.rs -
Add
searchfield toAppStateincrates/presentation/src/state.rs:
use std::sync::Arc;
use domain::ports::*;
#[derive(Clone)]
pub struct AppState {
pub users: Arc<dyn UserRepository>,
pub thoughts: Arc<dyn ThoughtRepository>,
pub likes: Arc<dyn LikeRepository>,
pub boosts: Arc<dyn BoostRepository>,
pub follows: Arc<dyn FollowRepository>,
pub blocks: Arc<dyn BlockRepository>,
pub tags: Arc<dyn TagRepository>,
pub api_keys: Arc<dyn ApiKeyRepository>,
pub top_friends: Arc<dyn TopFriendRepository>,
pub notifications: Arc<dyn NotificationRepository>,
pub remote_actors: Arc<dyn RemoteActorRepository>,
pub feed: Arc<dyn FeedRepository>,
pub search: Arc<dyn SearchPort>, // NEW
pub auth: Arc<dyn AuthService>,
pub hasher: Arc<dyn PasswordHasher>,
pub events: Arc<dyn EventPublisher>,
}
- Wire
PgSearchRepositoryinbuild_stateincrates/presentation/src/lib.rs:
Add postgres_search import and the field. The lib.rs build_state function currently returns AppState { ... } — add one line for search:
// At top of file, add:
use postgres_search::PgSearchRepository;
// In build_state, add to the AppState struct literal:
search: Arc::new(PgSearchRepository::new(pool.clone())),
Also add postgres-search to crates/presentation/Cargo.toml:
postgres-search = { workspace = true }
-
Run:
cargo check -p presentation— Expected: no errors. -
Update
search_handlerincrates/presentation/src/handlers/feed.rsto useSearchPortand return both thoughts and users:
Replace the existing search_handler function:
pub async fn search_handler(
State(s): State<AppState>,
OptionalAuthUser(viewer): OptionalAuthUser,
Query(q): Query<SearchQuery>,
) -> Result<Json<serde_json::Value>, ApiError> {
use domain::models::feed::PageParams;
let page = PageParams { page: q.page.unwrap_or(1), per_page: q.per_page.unwrap_or(20) };
let query = q.q.trim().to_string();
let (thoughts_result, users_result) = tokio::join!(
s.search.search_thoughts(&query, &page, viewer.as_ref()),
s.search.search_users(&query, &page),
);
let thoughts = thoughts_result?.items.into_iter().map(|e| serde_json::json!({
"id": e.thought.id.as_uuid(),
"content": e.thought.content.as_str(),
"author": to_user_response(&e.author),
"like_count": e.like_count,
"boost_count": e.boost_count,
"reply_count": e.reply_count,
"created_at": e.thought.created_at,
})).collect::<Vec<_>>();
let users = users_result?.items.into_iter().map(|u| to_user_response(&u)).collect::<Vec<_>>();
Ok(Json(serde_json::json!({
"query": query,
"thoughts": thoughts,
"users": users,
})))
}
Add use crate::handlers::auth::to_user_response; at the top of feed.rs if not already imported.
-
Run:
cargo build -p presentation— Expected: clean build. -
Smoke test:
# Start server
DATABASE_URL=postgres://postgres:postgres@localhost:5434/postgres JWT_SECRET=dev cargo run -p presentation &
sleep 2
# Register + post a thought + search
TOKEN=$(curl -s -X POST http://localhost:3000/auth/register \
-H 'content-type: application/json' \
-d '{"username":"searcher","email":"searcher@test.com","password":"pw"}' | jq -r .token)
curl -s -X POST http://localhost:3000/thoughts \
-H 'content-type: application/json' \
-H "Authorization: Bearer $TOKEN" \
-d '{"content":"searching for trigrams"}'
curl -s "http://localhost:3000/search?q=trigram" | jq .
kill %1
Expected: JSON with thoughts array containing the posted thought, users array.
- Commit:
git add crates/presentation/src/state.rs crates/presentation/src/lib.rs \
crates/presentation/src/handlers/feed.rs crates/presentation/Cargo.toml
git commit -m "feat(presentation): wire SearchPort, upgrade /search to return thoughts + users"
Self-Review
Spec coverage:
- ✅ pg_trgm extension + GIN indexes (Task 1)
- ✅
SearchPorttrait in domain (Task 2) - ✅
postgres-searchcrate filled in withPgSearchRepository(Task 3) - ✅ Existing ILIKE upgraded to trigram operator (Task 4)
- ✅ Presentation wired:
search: Arc<dyn SearchPort>in AppState (Task 5) - ✅
/searchendpoint returns both thoughts and users (Task 5)
Placeholder scan: None — all code blocks are complete.
Type consistency:
SearchPort::search_thoughts→ returnsPaginated<FeedEntry>— matches domain modelSearchPort::search_users→ returnsPaginated<User>— matches domain modelPgSearchRepository::new(pool: PgPool)— consistent with all other repo constructorsAppState.search: Arc<dyn SearchPort>— consistent with existing fields
Notes for implementer:
pg_trgm%operator default threshold is 0.3 — short single-word queries may return no results if the word is too short. The smoke test uses"trigram"(7 chars) which is long enough.CONCURRENTLYin migration lets the index build without locking the table — safe for production.postgres-searchdev-dependency onpostgrescrate is for seeding test data only — no runtime coupling.