> For the complete documentation index, see [llms.txt](https://mariadb.com/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mariadb.com/docs/server/reference/plugins/api-plugin/metadata_instrumentation.md).

# Metadata Instrumentation

The mysql\_mdl\_create, mysql\_mdl\_set\_status, and mysql\_mdl\_destroy macros, which instrument metadata locks for the Performance Schema.

> [`Instrumentation Interface`](/docs/server/reference/plugins/api-plugin/instrumentation_interface.md)

## Macros

| Name                                            | Description                             |
| ----------------------------------------------- | --------------------------------------- |
| [`mysql_mdl_create`](#mysql_mdl_create)         | Instrumented metadata lock creation.    |
| [`mysql_mdl_set_status`](#mysql_mdl_set_status) |                                         |
| [`mysql_mdl_destroy`](#mysql_mdl_destroy)       | Instrumented metadata lock destruction. |

***

### mysql\_mdl\_create

```cpp
#define mysql_mdl_create(I, K, T, D, S, F, L, I, K, T, D, S, F, L) NULL
```

Defined in psi/mysql\_mdl.h:74

Instrumented metadata lock creation.

#### Parameters

| Parameter | Type | Description            |
| --------- | ---- | ---------------------- |
| `I`       |      | Metadata lock identity |
| `K`       |      | Metadata key           |
| `T`       |      | Metadata lock type     |
| `D`       |      | Metadata lock duration |
| `S`       |      | Metadata lock status   |
| `F`       |      | request source file    |
| `L`       |      | request source line    |
| `I`       |      | Metadata lock identity |
| `K`       |      | Metadata key           |
| `T`       |      | Metadata lock type     |
| `D`       |      | Metadata lock duration |
| `S`       |      | Metadata lock status   |
| `F`       |      | request source file    |
| `L`       |      | request source line    |

***

### mysql\_mdl\_set\_status

```cpp
#define mysql_mdl_set_status(L, S, L, S) do {} while (0)
```

Defined in psi/mysql\_mdl.h:81

***

### mysql\_mdl\_destroy

```cpp
#define mysql_mdl_destroy(M, M) do {} while (0)
```

Defined in psi/mysql\_mdl.h:95

Instrumented metadata lock destruction.

#### Parameters

| Parameter | Type | Description   |
| --------- | ---- | ------------- |
| `M`       |      | Metadata lock |
| `M`       |      | Metadata lock |