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2025-11-30 09:01:40 +08:00

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# Database Diagnostics
SQLite database troubleshooting for claude-mem.
## Database Overview
Claude-mem uses SQLite3 for persistent storage:
- **Location:** `~/.claude-mem/claude-mem.db`
- **Library:** better-sqlite3 (synchronous, not bun:sqlite)
- **Features:** FTS5 full-text search, triggers, indexes
- **Tables:** observations, sessions, user_prompts, observations_fts, sessions_fts, prompts_fts
## Basic Database Checks
### Check Database Exists
```bash
# Check file exists
ls -lh ~/.claude-mem/claude-mem.db
# Check file size
du -h ~/.claude-mem/claude-mem.db
# Check permissions
ls -la ~/.claude-mem/claude-mem.db
```
**Expected:**
- File exists
- Size: 100KB - 10MB+ (depends on usage)
- Permissions: Readable/writable by your user
### Check Database Integrity
```bash
# Run integrity check
sqlite3 ~/.claude-mem/claude-mem.db "PRAGMA integrity_check;"
```
**Expected output:** `ok`
**If errors appear:**
- Database corrupted
- Backup immediately: `cp ~/.claude-mem/claude-mem.db ~/.claude-mem/claude-mem.db.backup`
- Consider recreating (data loss)
## Data Inspection
### Count Records
```bash
# Observation count
sqlite3 ~/.claude-mem/claude-mem.db "SELECT COUNT(*) FROM observations;"
# Session count
sqlite3 ~/.claude-mem/claude-mem.db "SELECT COUNT(*) FROM sessions;"
# User prompt count
sqlite3 ~/.claude-mem/claude-mem.db "SELECT COUNT(*) FROM user_prompts;"
# FTS5 table counts (should match main tables)
sqlite3 ~/.claude-mem/claude-mem.db "SELECT COUNT(*) FROM observations_fts;"
sqlite3 ~/.claude-mem/claude-mem.db "SELECT COUNT(*) FROM sessions_fts;"
sqlite3 ~/.claude-mem/claude-mem.db "SELECT COUNT(*) FROM prompts_fts;"
```
### View Recent Records
```bash
# Recent observations
sqlite3 ~/.claude-mem/claude-mem.db "
SELECT
created_at,
type,
title,
project
FROM observations
ORDER BY created_at DESC
LIMIT 10;
"
# Recent sessions
sqlite3 ~/.claude-mem/claude-mem.db "
SELECT
created_at,
request,
project
FROM sessions
ORDER BY created_at DESC
LIMIT 5;
"
# Recent user prompts
sqlite3 ~/.claude-mem/claude-mem.db "
SELECT
created_at,
prompt
FROM user_prompts
ORDER BY created_at DESC
LIMIT 10;
"
```
### Check Projects
```bash
# List all projects
sqlite3 ~/.claude-mem/claude-mem.db "
SELECT DISTINCT project
FROM observations
ORDER BY project;
"
# Count observations per project
sqlite3 ~/.claude-mem/claude-mem.db "
SELECT
project,
COUNT(*) as count
FROM observations
GROUP BY project
ORDER BY count DESC;
"
```
## Database Schema
### View Table Structure
```bash
# List all tables
sqlite3 ~/.claude-mem/claude-mem.db ".tables"
# Show observations table schema
sqlite3 ~/.claude-mem/claude-mem.db ".schema observations"
# Show all schemas
sqlite3 ~/.claude-mem/claude-mem.db ".schema"
```
### Expected Tables
- `observations` - Main observation records
- `observations_fts` - FTS5 virtual table for full-text search
- `sessions` - Session summary records
- `sessions_fts` - FTS5 virtual table for session search
- `user_prompts` - User prompt records
- `prompts_fts` - FTS5 virtual table for prompt search
## FTS5 Synchronization
The FTS5 tables should stay synchronized with main tables via triggers.
### Check FTS5 Sync
```bash
# Compare counts
sqlite3 ~/.claude-mem/claude-mem.db "
SELECT
(SELECT COUNT(*) FROM observations) as observations,
(SELECT COUNT(*) FROM observations_fts) as observations_fts,
(SELECT COUNT(*) FROM sessions) as sessions,
(SELECT COUNT(*) FROM sessions_fts) as sessions_fts,
(SELECT COUNT(*) FROM user_prompts) as prompts,
(SELECT COUNT(*) FROM prompts_fts) as prompts_fts;
"
```
**Expected:** All pairs should match (observations = observations_fts, etc.)
### Fix FTS5 Desync
If FTS5 counts don't match, triggers may have failed. Restart worker to rebuild:
```bash
pm2 restart claude-mem-worker
```
The worker will rebuild FTS5 indexes on startup if they're out of sync.
## Common Database Issues
### Issue: Database Doesn't Exist
**Cause:** First run, or database was deleted
**Fix:** Database will be created automatically on first observation. No action needed.
### Issue: Database is Empty (0 Records)
**Cause:**
- New installation (normal)
- Data was deleted
- Worker not processing observations
**Fix:**
1. Create test observation (use any skill and cancel)
2. Check worker logs for errors:
```bash
pm2 logs claude-mem-worker --lines 50 --nostream
```
3. Verify observation appears in database
### Issue: Database Permission Denied
**Cause:** File permissions wrong, database owned by different user
**Fix:**
```bash
# Check ownership
ls -la ~/.claude-mem/claude-mem.db
# Fix permissions (if needed)
chmod 644 ~/.claude-mem/claude-mem.db
chown $USER ~/.claude-mem/claude-mem.db
```
### Issue: Database Locked
**Cause:**
- Multiple processes accessing database
- Crash left lock file
- Long-running transaction
**Fix:**
```bash
# Check for lock file
ls -la ~/.claude-mem/claude-mem.db-wal
ls -la ~/.claude-mem/claude-mem.db-shm
# Remove lock files (only if worker is stopped!)
pm2 stop claude-mem-worker
rm ~/.claude-mem/claude-mem.db-wal ~/.claude-mem/claude-mem.db-shm
pm2 start claude-mem-worker
```
### Issue: Database Growing Too Large
**Cause:** Too many observations accumulated
**Check size:**
```bash
du -h ~/.claude-mem/claude-mem.db
sqlite3 ~/.claude-mem/claude-mem.db "SELECT COUNT(*) FROM observations;"
```
**Options:**
1. Delete old observations (manual cleanup):
```bash
sqlite3 ~/.claude-mem/claude-mem.db "
DELETE FROM observations
WHERE created_at < datetime('now', '-90 days');
"
```
2. Vacuum to reclaim space:
```bash
sqlite3 ~/.claude-mem/claude-mem.db "VACUUM;"
```
3. Archive and start fresh:
```bash
mv ~/.claude-mem/claude-mem.db ~/.claude-mem/claude-mem.db.archive
pm2 restart claude-mem-worker
```
## Database Recovery
### Backup Database
**Before any destructive operations:**
```bash
cp ~/.claude-mem/claude-mem.db ~/.claude-mem/claude-mem.db.backup
```
### Restore from Backup
```bash
pm2 stop claude-mem-worker
cp ~/.claude-mem/claude-mem.db.backup ~/.claude-mem/claude-mem.db
pm2 start claude-mem-worker
```
### Export Data
Export to JSON for safekeeping:
```bash
# Export observations
sqlite3 ~/.claude-mem/claude-mem.db -json "SELECT * FROM observations;" > observations.json
# Export sessions
sqlite3 ~/.claude-mem/claude-mem.db -json "SELECT * FROM sessions;" > sessions.json
# Export prompts
sqlite3 ~/.claude-mem/claude-mem.db -json "SELECT * FROM user_prompts;" > prompts.json
```
### Recreate Database
**WARNING: Data loss. Backup first!**
```bash
# Stop worker
pm2 stop claude-mem-worker
# Backup current database
cp ~/.claude-mem/claude-mem.db ~/.claude-mem/claude-mem.db.old
# Delete database
rm ~/.claude-mem/claude-mem.db
# Start worker (creates new database)
pm2 start claude-mem-worker
```
## Database Statistics
### Storage Analysis
```bash
# Database file size
du -h ~/.claude-mem/claude-mem.db
# Record counts by type
sqlite3 ~/.claude-mem/claude-mem.db "
SELECT
type,
COUNT(*) as count
FROM observations
GROUP BY type
ORDER BY count DESC;
"
# Observations per month
sqlite3 ~/.claude-mem/claude-mem.db "
SELECT
strftime('%Y-%m', created_at) as month,
COUNT(*) as count
FROM observations
GROUP BY month
ORDER BY month DESC;
"
# Average observation size (characters)
sqlite3 ~/.claude-mem/claude-mem.db "
SELECT
AVG(LENGTH(content)) as avg_content_length,
MAX(LENGTH(content)) as max_content_length
FROM observations;
"
```
## Advanced Queries
### Find Specific Observations
```bash
# Search by keyword (FTS5)
sqlite3 ~/.claude-mem/claude-mem.db "
SELECT title, created_at
FROM observations_fts
WHERE observations_fts MATCH 'authentication'
ORDER BY created_at DESC;
"
# Find by type
sqlite3 ~/.claude-mem/claude-mem.db "
SELECT title, created_at
FROM observations
WHERE type = 'bugfix'
ORDER BY created_at DESC
LIMIT 10;
"
# Find by file path
sqlite3 ~/.claude-mem/claude-mem.db "
SELECT title, created_at
FROM observations
WHERE file_path LIKE '%auth%'
ORDER BY created_at DESC;
"
```
## Database Maintenance
### Regular Maintenance Tasks
```bash
# Analyze for query optimization
sqlite3 ~/.claude-mem/claude-mem.db "ANALYZE;"
# Rebuild FTS5 indexes
sqlite3 ~/.claude-mem/claude-mem.db "
INSERT INTO observations_fts(observations_fts) VALUES('rebuild');
INSERT INTO sessions_fts(sessions_fts) VALUES('rebuild');
INSERT INTO prompts_fts(prompts_fts) VALUES('rebuild');
"
# Vacuum to reclaim space
sqlite3 ~/.claude-mem/claude-mem.db "VACUUM;"
```
**Run monthly to keep database healthy.**