Database & Migrations

Overview

Loom uses SQLite with Write-Ahead Logging (WAL) for thread persistence, authentication, analytics, and feature flags. The database is designed for multi-reader, single-writer workloads.

Database migrations run automatically on server startup. You do not need to run migrations manually.

Database Location

The database path is configured via:

export LOOM_SERVER_DATABASE_URL=sqlite:/var/lib/loom-server/loom.db?mode=rwc

Or in NixOS:

services.loom-server.databasePath = "/var/lib/loom-server/loom.db";

SQLite Configuration

Loom uses these SQLite settings:

Journal mode: WAL (Write-Ahead Logging) for better concurrency
Synchronous: NORMAL (balance between safety and performance)
Foreign keys: Enabled
Auto vacuum: Incremental

Schema Organization

The database schema is organized into these domains:

Threads

Conversation persistence and FTS search

Authentication

Users, organizations, teams, sessions, API keys

SCM

Git repositories, commits, webhooks, mirrors

Analytics

Events, sessions, crash reports, cron monitoring

Feature Flags

Flags, experiments, exposures

Secrets

Weaver secrets with encryption-at-rest

Migration System

Migrations are numbered SQL files in crates/loom-server/migrations/:

migrations/
├── 001_create_threads.sql
├── 002_add_visibility.sql
├── 003_add_git_metadata.sql
├── ...
└── 040_whatsapp.sql

Migration Naming Convention

NNN_description.sql

NNN: Three-digit sequence number (001, 002, …)
description: Short snake_case description

Examples:

020_scm_repos.sql
030_feature_flags.sql
032_analytics.sql

How Migrations Run

Migrations are embedded in the binary via include_str!() and executed sequentially on startup:

crates/loom-server/src/db/mod.rs

pub async fn run_migrations(pool: &SqlitePool) -> Result<(), ServerError> {
    let m1 = include_str!("../../migrations/001_create_threads.sql");
    sqlx::query(m1).execute(pool).await?;
    
    let m2 = include_str!("../../migrations/002_add_visibility.sql");
    if let Err(e) = sqlx::query(m2).execute(pool).await {
        // Handle duplicate column errors (idempotency)
        ...
    }
    
    // ... more migrations
}

cargo2nix doesn’t track include_str!() file changes. After adding migrations:

Run cargo2nix-update to regenerate Cargo.nix
Commit Cargo.nix along with your migration files
Without this step, the deployed binary will NOT include the new migration!

Adding a Migration

Find the next migration number

ls crates/loom-server/migrations/ | tail -1
# 040_whatsapp.sql
# Next number: 041

Create the migration file

touch crates/loom-server/migrations/041_my_feature.sql

Write the migration SQL

041_my_feature.sql

-- Copyright (c) 2025 Geoffrey Huntley <[email protected]>. All rights reserved.
-- SPDX-License-Identifier: Proprietary

-- Add my_feature table
CREATE TABLE IF NOT EXISTS my_feature (
    id TEXT PRIMARY KEY NOT NULL,
    name TEXT NOT NULL,
    created_at TEXT NOT NULL
);

CREATE INDEX IF NOT EXISTS idx_my_feature_name
    ON my_feature(name);

Always use IF NOT EXISTS and IF NOT EXISTS for idempotency. Migrations may be run multiple times.

Add the migration to db/mod.rs

crates/loom-server/src/db/mod.rs

let m41 = include_str!("../../migrations/041_my_feature.sql");
for stmt in m41.split(';').filter(|s| !s.trim().is_empty()) {
    if let Err(e) = sqlx::query(stmt).execute(pool).await {
        let msg = e.to_string();
        if !msg.contains("already exists") && !msg.contains("duplicate column") {
            return Err(e.into());
        }
    }
}

Test the migration

# Delete test database
rm -f /tmp/loom-test.db

# Run server (migrations run on startup)
cargo run -p loom-server -- \
  LOOM_SERVER_DATABASE_URL=sqlite:/tmp/loom-test.db \
  LOOM_SERVER_ANTHROPIC_API_KEY=sk-test

# Verify tables exist
sqlite3 /tmp/loom-test.db ".tables"

Force rebuild for cargo2nix

cargo2nix-update
git add Cargo.nix crates/loom-server/migrations/041_my_feature.sql
git commit -m "Add my_feature migration"

Migration Examples

Simple Table Creation

020_scm_repos.sql

CREATE TABLE IF NOT EXISTS scm_repos (
    id TEXT PRIMARY KEY NOT NULL,
    org_id TEXT NOT NULL,
    provider TEXT NOT NULL,
    clone_url TEXT NOT NULL,
    local_path TEXT NOT NULL,
    created_at TEXT NOT NULL,
    updated_at TEXT NOT NULL,
    last_fetched_at TEXT,
    FOREIGN KEY (org_id) REFERENCES orgs(id)
);

CREATE INDEX IF NOT EXISTS idx_scm_repos_org_id
    ON scm_repos(org_id);

CREATE INDEX IF NOT EXISTS idx_scm_repos_provider
    ON scm_repos(provider);

Full-Text Search (FTS5)

005_thread_fts.sql

CREATE VIRTUAL TABLE IF NOT EXISTS thread_fts USING fts5(
    thread_id UNINDEXED,
    title,
    content,
    tokenize = 'porter unicode61'
);

CREATE TRIGGER IF NOT EXISTS thread_fts_insert
AFTER INSERT ON threads
BEGIN
    INSERT INTO thread_fts(thread_id, title, content)
    VALUES (NEW.id, NEW.title, json_extract(NEW.full_json, '$.conversation'));
END;

CREATE TRIGGER IF NOT EXISTS thread_fts_update
AFTER UPDATE ON threads
BEGIN
    DELETE FROM thread_fts WHERE thread_id = OLD.id;
    INSERT INTO thread_fts(thread_id, title, content)
    VALUES (NEW.id, NEW.title, json_extract(NEW.full_json, '$.conversation'));
END;

CREATE TRIGGER IF NOT EXISTS thread_fts_delete
AFTER DELETE ON threads
BEGIN
    DELETE FROM thread_fts WHERE thread_id = OLD.id;
END;

JSON Columns

030_feature_flags.sql

CREATE TABLE IF NOT EXISTS flags (
    id TEXT PRIMARY KEY NOT NULL,
    key TEXT NOT NULL UNIQUE,
    name TEXT NOT NULL,
    description TEXT,
    
    -- JSON column for conditions
    conditions JSON,
    
    -- JSON column for variants
    variants JSON NOT NULL,
    
    created_at TEXT NOT NULL,
    updated_at TEXT NOT NULL
);

-- Query JSON columns
SELECT key, json_extract(variants, '$.control.value') as control_value
FROM flags
WHERE json_extract(conditions, '$.enabled') = 1;

Adding Columns to Existing Tables

023_add_username.sql

-- Add username column (nullable first, then backfill)
ALTER TABLE users ADD COLUMN username TEXT;

-- Create unique index
CREATE UNIQUE INDEX IF NOT EXISTS idx_users_username
    ON users(username)
    WHERE username IS NOT NULL;

Schema Inspection

List All Tables

sqlite3 /var/lib/loom-server/loom.db ".tables"

Show Table Schema

sqlite3 /var/lib/loom-server/loom.db ".schema threads"

Show Indexes

sqlite3 /var/lib/loom-server/loom.db ".indexes threads"

Query Metadata

-- Show all tables
SELECT name FROM sqlite_master WHERE type='table';

-- Show all indexes
SELECT name, tbl_name FROM sqlite_master WHERE type='index';

-- Show FTS tables
SELECT name FROM sqlite_master WHERE type='table' AND name LIKE '%_fts';

-- Show triggers
SELECT name, tbl_name FROM sqlite_master WHERE type='trigger';

Database Backup

Manual Backup

# Stop the server first
sudo systemctl stop loom-server

# Copy database file
cp /var/lib/loom-server/loom.db /backup/loom-$(date +%Y%m%d).db

# Copy WAL files too (if they exist)
cp /var/lib/loom-server/loom.db-shm /backup/
cp /var/lib/loom-server/loom.db-wal /backup/

# Restart server
sudo systemctl start loom-server

Online Backup

# Use SQLite's backup API (doesn't require stopping server)
sqlite3 /var/lib/loom-server/loom.db ".backup /backup/loom-$(date +%Y%m%d).db"

Automated Backups

backup-service.nix

systemd.services.loom-backup = {
  description = "Backup Loom database";
  serviceConfig = {
    Type = "oneshot";
    ExecStart = ''
      ${pkgs.sqlite}/bin/sqlite3 /var/lib/loom-server/loom.db \
        ".backup /backup/loom-$(date +%Y%m%d).db"
    '';
  };
};

systemd.timers.loom-backup = {
  wantedBy = [ "timers.target" ];
  timerConfig = {
    OnCalendar = "daily";
    Persistent = true;
  };
};

Database Maintenance

Vacuum

Reclaim space and defragment:

sqlite3 /var/lib/loom-server/loom.db "VACUUM;"

Analyze

Update query optimizer statistics:

sqlite3 /var/lib/loom-server/loom.db "ANALYZE;"

Check Integrity

sqlite3 /var/lib/loom-server/loom.db "PRAGMA integrity_check;"

Optimize

sqlite3 /var/lib/loom-server/loom.db "PRAGMA optimize;"

Monitoring

Database Size

du -h /var/lib/loom-server/loom.db*

Table Sizes

SELECT 
    name,
    (SELECT COUNT(*) FROM sqlite_master WHERE tbl_name = m.name) as objects,
    pgsize
FROM dbstat m
GROUP BY name
ORDER BY pgsize DESC;

WAL Status

PRAGMA wal_checkpoint(PASSIVE);

Troubleshooting

Migration fails with 'duplicate column' error

This is expected behavior for idempotent migrations. The error is caught and ignored:

if let Err(e) = sqlx::query(m2).execute(pool).await {
    let msg = e.to_string();
    if !msg.contains("duplicate column") {
        return Err(e.into());
    }
}

If a different error occurs, check the migration SQL syntax.

Database locked errors

SQLite uses WAL mode for better concurrency, but you may still see lock errors with many concurrent writes.Fix:

Ensure only one writer process (loom-server)
Close SQLite CLI sessions before starting the server
Check for stale lock files: rm -f /var/lib/loom-server/*.db-shm

New migration not included in deployed binary

cargo2nix doesn’t track include_str!() file changes.Fix:

cargo2nix-update
git add Cargo.nix
git commit -m "Update Cargo.nix for new migration"
git push origin trunk

FTS search not working

Check that FTS triggers are installed:

SELECT name FROM sqlite_master WHERE type='trigger' AND tbl_name='threads';

Rebuild FTS index:

DELETE FROM thread_fts;
INSERT INTO thread_fts(thread_id, title, content)
SELECT id, title, json_extract(full_json, '$.conversation')
FROM threads;

Current Schema (as of migration 040)

The database includes 40+ tables:

Threads: threads, thread_fts, thread_repos, thread_commits
Auth: users, orgs, teams, sessions, api_keys, impersonation_sessions
SCM: scm_repos, scm_webhooks, scm_mirrors, scm_maintenance_log
GitHub: github_installations, github_installation_repos
Analytics: analytics_events, analytics_user_aliases, sessions, session_aggregates
Crashes: crash_events, crash_api_keys, crash_symbol_artifacts
Feature Flags: flags, flag_exposures
Crons: cron_monitors, cron_checkins
Jobs: job_runs
Secrets: weaver_secrets
WhatsApp: whatsapp_orgs, whatsapp_inbound_messages
Misc: cse_cache, ws_tokens, docs_fts, wgtunnel_tunnels, clips, clip_stars

Get Started

Core Features

Architecture

Integrations

Observability

Deployment

​Overview

​Database Location

​SQLite Configuration

​Schema Organization

Threads

Authentication

SCM

Analytics

Feature Flags

Secrets

​Migration System

​Migration Naming Convention

​How Migrations Run

​Adding a Migration

​Migration Examples

​Simple Table Creation

​Full-Text Search (FTS5)

​JSON Columns

​Adding Columns to Existing Tables

​Schema Inspection

​List All Tables

​Show Table Schema

​Show Indexes

​Query Metadata

​Database Backup

​Manual Backup

​Online Backup

​Automated Backups

​Database Maintenance

​Vacuum

​Analyze

​Check Integrity

​Optimize

​Monitoring

​Database Size

​Table Sizes

​WAL Status

​Troubleshooting

​Current Schema (as of migration 040)

​Next Steps

Server Setup

Configuration

Build docs developers (and LLMs) love

Overview

Database Location

SQLite Configuration

Schema Organization

Migration System

Migration Naming Convention

How Migrations Run

Adding a Migration

Migration Examples

Simple Table Creation

Full-Text Search (FTS5)

JSON Columns

Adding Columns to Existing Tables

Schema Inspection

List All Tables

Show Table Schema

Show Indexes

Query Metadata

Database Backup

Manual Backup

Online Backup

Automated Backups

Database Maintenance

Vacuum

Analyze

Check Integrity

Optimize

Monitoring

Database Size

Table Sizes

WAL Status

Troubleshooting

Current Schema (as of migration 040)

Next Steps