# Diagnostic Command

> Source: https://docs.synthesized.io/tdk/latest/user_guide/080_troubleshooting/debugging/diagnostic_command
> For the complete documentation index, see [llms.txt](https://docs.synthesized.io/llms.txt).

Use TDK’s built-in diagnostic tools to quickly identify and resolve issues.

## Overview

The diagnostic command checks:

- Database connectivity
- Configuration validity
- Schema access
- Foreign key relationships
- Performance metrics

## Running Diagnostics

### CLI Mode

```shell
tdk diagnostic \
  --config-file workflow.yaml \
  --inventory-file inventory.yaml
```

### Specific Checks

```shell
# Check database connection only
tdk diagnostic --check-connection

# Check configuration validity
tdk diagnostic --check-config

# Check schema metadata
tdk diagnostic --check-schema

# Run all checks
tdk diagnostic --check-all
```

## Diagnostic Output

### Successful Output

```
✓ Database connection: OK
✓ Configuration valid: OK
✓ Schema accessible: 15 tables found
✓ Foreign keys: 23 relationships detected
✓ Permissions: READ/WRITE access confirmed

Summary: All checks passed
```

### Error Output

```
✗ Database connection: FAILED
  Error: Connection refused (Connection refused)
  Solution: Verify database is running and accessible

✓ Configuration valid: OK

⚠ Schema accessible: WARNING
  Warning: 3 tables not accessible
  Tables: private.secrets, admin.config, internal.logs
  Solution: Grant SELECT permission or exclude from workflow

✓ Foreign keys: 20 relationships detected

Summary: 1 error, 1 warning
```

## Connection Check Details

```shell
tdk diagnostic --check-connection --verbose
```

Output:

```
Testing connection to: jdbc:postgresql://localhost:5432/mydb
  Hostname resolution: ✓ localhost → 127.0.0.1
  Port accessibility: ✓ Port 5432 is open
  JDBC driver: ✓ org.postgresql.Driver loaded
  Authentication: ✓ Credentials accepted
  Database access: ✓ Can query system tables
  Connection time: 234ms

Result: Connection successful
```

## Schema Check

```shell
tdk diagnostic --check-schema
```

Output:

```
Discovered tables: 15
  public.customers (10 columns, 50000 rows)
  public.orders (8 columns, 150000 rows)
  public.products (6 columns, 500 rows)
  ...

Foreign keys: 23
  orders.customer_id → customers.id
  order_items.order_id → orders.id
  order_items.product_id → products.id
  ...

Indexes: 45
  Primary keys: 15
  Foreign key indexes: 23
  Additional indexes: 7

Result: Schema analysis complete
```

## Configuration Check

```shell
tdk diagnostic --check-config --config-file workflow.yaml
```

Output:

```
✓ YAML syntax: Valid
✓ Mode specified: MASKING
✓ Table patterns: 3 patterns defined
✓ Transformations: 12 transformations configured
✓ No circular dependencies detected

Warnings:
  ⚠ Table pattern "public.audit_*" matches no tables

Result: Configuration valid with 1 warning
```

## Performance Check

```shell
tdk diagnostic --check-performance
```

Output:

```
Testing read performance...
  Rows read: 10000 in 2.1s (4762 rows/sec)

Testing write performance...
  Rows written: 10000 in 3.5s (2857 rows/sec)

Memory usage:
  Current: 512 MB
  Max: 2048 MB
  Available: 1536 MB

Result: Performance is acceptable
```

## Troubleshooting with Diagnostics

### Connection Issues

```shell
tdk diagnostic --check-connection 2>&1 | tee connection-test.log
```

Review `connection-test.log` for detailed error messages.

### Permission Issues

```shell
tdk diagnostic --check-schema --verbose
```

Look for "Permission denied" or "Access denied" messages.

## See Also

- [Reading Logs](https://docs.synthesized.io/tdk/latest/user_guide/080_troubleshooting/debugging/logs)
- [Connection Issues](https://docs.synthesized.io/tdk/latest/user_guide/080_troubleshooting/common_issues/connection)
- [CLI Reference](https://docs.synthesized.io/tdk/latest/user_guide/040_reference/api_reference/command_line_interface)