# blocking

> Command: `blocking`  
> Category: **Performance Monitoring**  
> Status: Production Ready

## Description

Show blocking sessions and lock chains in the SAP HANA database. This command helps identify which sessions are holding locks and which sessions are waiting for those locks, including detailed information about lock duration, type, and affected database objects.

## Syntax

```bash
hana-cli blocking [options]
```

## Aliases

- `b`
- `locks`

## Command Diagram

```mermaid
graph TD
    Start([hana-cli blocking]) --> Input{Input Parameters}
    Input -->|limit| Limit[Maximum Results<br/>Default: 50]
    Input -->|details| Details[Show Session Details<br/>Default: false]
    
    Limit --> Query[Query M_LOCKS<br/>System View]
    Details --> Query
    
    Query --> Filter[Filter Non-Exclusive<br/>Lock Types]
    
    Filter --> HasResults{Has<br/>Results?}
    
    HasResults -->|No| NoBlocking[Display: No<br/>Blocking Locks]
    HasResults -->|Yes| Display[Display Lock<br/>Information]
    
    Display --> CheckDetails{Details<br/>Enabled?}
    
    CheckDetails -->|Yes| WaiterInfo[Fetch Waiter<br/>Session Details]
    CheckDetails -->|No| Complete([Command Complete])
    
    WaiterInfo --> DisplayDetails[Display User,<br/>Application, Host,<br/>Wait Time]
    
    DisplayDetails --> Complete
    NoBlocking --> Complete
    
    style Start fill:#0092d1
    style Complete fill:#2ecc71
    style Input fill:#f39c12
    style HasResults fill:#f39c12
    style CheckDetails fill:#f39c12
    style WaiterInfo fill:#9b59b6
```

## Parameters

### Options

| Option      | Alias | Type    | Default | Description                                                      |
|-------------|-------|---------|---------|------------------------------------------------------------------|
| `--limit`   | `-l`  | number  | `50`    | Maximum number of blocking locks to display                      |
| `--details` | `-d`  | boolean | `false` | Show detailed information about waiter sessions                  |

### Connection Parameters

| Option    | Alias | Type    | Default | Description                                          |
|-----------|-------|---------|---------|------------------------------------------------------|
| `--admin` | `-a`  | boolean | `false` | Connect via admin (default-env-admin.json)           |
| `--conn`  | -     | string  | -       | Connection filename to override default-env.json     |

### Troubleshooting

| Option              | Alias     | Type    | Default | Description                                                                 |
|---------------------|-----------|---------|---------|-----------------------------------------------------------------------------|
| `--disableVerbose`  | `--quiet` | boolean | `false` | Disable verbose output                                                      |
| `--debug`           | `-d`      | boolean | `false` | Debug hana-cli itself by adding output of intermediate details             |

## Examples

### Basic Usage

```bash
hana-cli blocking
```

Display blocking sessions and lock chains with default settings.

### Show Detailed Information

```bash
hana-cli blocking --limit 50 --details
```

Display blocking locks with detailed information about waiter sessions including user, application, and wait time.

### Limit Results

```bash
hana-cli blocking --limit 25
```

Display only the top 25 blocking locks.

## Related Commands

See the [Commands Reference](../all-commands.md) for other commands in this category.

## See Also

- [Category: Performance Monitoring](..)
- [All Commands A-Z](../all-commands.md)