# Information Schema Plugins: SHOW and FLUSH Statements

{% hint style="info" %}
This page contains background information for MariaDB developers.
{% endhint %}

Information Schema plugins support [SHOW](/docs/server/reference/sql-statements/administrative-sql-statements/show.md) and [FLUSH](/docs/server/reference/sql-statements/administrative-sql-statements/flush-commands/flush.md) statements.

## SHOW

`SHOW` statement support is enabled by default. A plugin only has to specify column names for the `SHOW` statement in the `old_name` member of the field declaration structure. Columns with the `old_name` set to `0` are hidden from the `SHOW` statement. If all columns are hidden, the `SHOW` statement doesn't work for this plugin.

Note that ` SHOW`` `` `*`statement`* is a user-friendly shortcut – it's easier to type and view. If the Information Schema table contains many columns, the `SHOW` statement is supposed to display only the most important columns, so that the output fits nicely on the 80x25 terminal screen.

Consider an example, the [LOCALES plugin](/docs/server/reference/data-types/string-data-types/character-sets/internationalization-and-localization/locales-plugin.md):

```c
static ST_FIELD_INFO locale_info_locale_fields_info[]=
{
  {"ID", 4, MYSQL_TYPE_LONGLONG, 0, 0, "Id", 0},
  {"NAME", 255, MYSQL_TYPE_STRING, 0, 0, "Name", 0},
  {"DESCRIPTION", 255,  MYSQL_TYPE_STRING, 0, 0, "Description", 0},
  {"MAX_MONTH_NAME_LENGTH", 4, MYSQL_TYPE_LONGLONG, 0, 0, 0, 0},
  {"MAX_DAY_NAME_LENGTH", 4, MYSQL_TYPE_LONGLONG, 0, 0, 0, 0},
  {"DECIMAL_POINT", 2, MYSQL_TYPE_STRING, 0, 0, 0, 0},
  {"THOUSAND_SEP", 2, MYSQL_TYPE_STRING, 0, 0, 0, 0},
  {"ERROR_MESSAGE_LANGUAGE", 64, MYSQL_TYPE_STRING, 0, 0, "Error_Message_Language", 0},
  {0, 0, MYSQL_TYPE_STRING, 0, 0, 0, 0}
};
```

While the [INFORMATION\_SCHEMA.LOCALES](/docs/server/reference/system-tables/information-schema/information-schema-tables/information-schema-locales-table.md) table has 8 columns, the [SHOW LOCALES](/docs/server/reference/sql-statements/administrative-sql-statements/show/show-locales.md) statement only displays 4 of them:

```sql
MariaDB [test]> SHOW LOCALES;
+-----+-------+-------------------------------------+------------------------+
| Id  | Name  | Description                         | Error_Message_Language |
+-----+-------+-------------------------------------+------------------------+
|   0 | en_US | English - United States             | english                |
|   1 | en_GB | English - United Kingdom            | english                |
|   2 | ja_JP | Japanese - Japan                    | japanese               |
|   3 | sv_SE | Swedish - Sweden                    | swedish                |
...
```

## FLUSH

To support the `FLUSH` statement, a plugin must declare the `reset_table` callback. For example, in the [QUERY\_RESPONSE\_TIME](https://github.com/mariadb-corporation/docs-server/blob/test/general-resources/community/plugins/other-plugins/query-response-time-plugin.md) plugin:

```c
static int query_response_time_info_init(void *p)
{
  ST_SCHEMA_TABLE *i_s_query_response_time= (ST_SCHEMA_TABLE *) p;
  i_s_query_response_time->fields_info= query_response_time_fields_info;
  i_s_query_response_time->fill_table= query_response_time_fill;
  i_s_query_response_time->reset_table= query_response_time_flush;
  query_response_time_init();
  return 0;
}
```

<sub>*This page is licensed: CC BY-SA / Gnu FDL*</sub>

{% @marketo/form formId="4316" %}


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://mariadb.com/docs/server/reference/product-development/plugin-development/information-schema-plugins-show-and-flush-statements.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.