[DOCS] Add custom metrics documentation for Database Monitoring

config/_default/menus/main.en.yaml

@@ -4933,41 +4933,51 @@ menu:
       parent: dbm
       identifier: dbm_data_collected
       weight: 10
+    - name: Collecting Custom Metrics
+      url: database_monitoring/custom_metrics/
+      parent: dbm
+      identifier: dbm_custom_metrics
+      weight: 11
+    - name: Exploring Custom Metrics
+      url: database_monitoring/custom_metrics/exploring_custom_metrics
+      parent: dbm_custom_metrics
+      identifier: dbm_custom_metrics_exploring
+      weight: 1
     - name: Exploring Database Hosts
       url: database_monitoring/database_hosts/
       parent: dbm
       identifier: dbm_database_hosts
-      weight: 11
+      weight: 12
     - name: Exploring Query Metrics
       url: database_monitoring/query_metrics/
       parent: dbm
       identifier: dbm_query_metrics
-      weight: 12
+      weight: 13
     - name: Exploring Query Samples
       url: database_monitoring/query_samples/
       parent: dbm
       identifier: dbm_query_samples
-      weight: 13
+      weight: 14
     - name: Exploring Database Schemas
       url: database_monitoring/schema_explorer
       parent: dbm
       identifier: dbm_schema_explorer
-      weight: 14
+      weight: 15
     - name: Exploring Recommendations
       url: database_monitoring/recommendations/
       parent: dbm
       identifier: dbm_recommendations
-      weight: 15
+      weight: 16
     - name: Troubleshooting
       url: database_monitoring/troubleshooting/
       parent: dbm
       identifier: dbm_troubleshooting
-      weight: 16
+      weight: 17
     - name: Guides
       url: database_monitoring/guide/
       parent: dbm
       identifier: dbm_guides
-      weight: 17
+      weight: 18
     - name: Data Streams Monitoring
       url: data_streams/
       pre: datastreams-monitoring

content/en/database_monitoring/_index.md

@@ -113,6 +113,10 @@ The [Query Samples view][3] helps you understand which queries are running at a
 
 {{< img src="database_monitoring/dbm-explain-plan-3.png" alt="Database Monitoring" style="width:100%;">}}
 
+### Collect custom metrics
+
+Use [`custom_queries`][7] to collect metrics from your own database tables — application state, business counters, queue depths, or any data you want correlated with query performance.
+
 ### Visualize everything on enriched dashboards
 
 Quickly pinpoint problem areas by viewing database and system metrics together on enriched integration dashboards for both self-hosted and cloud-managed instances. Clone dashboards for customization and enhancement with your own custom metrics. Click the **Dashboards** link at the top of the Query Metrics and Query Samples pages to go to the Database Monitoring dashboards.
@@ -146,3 +150,4 @@ The [Recommendations page][6] highlights problems and optimization opportunities
 [4]: /database_monitoring/query_metrics/#explain-plans
 [5]: /database_monitoring/database_hosts/
 [6]: /database_monitoring/recommendations/
+[7]: /database_monitoring/custom_metrics/

content/en/database_monitoring/custom_metrics/_index.md

@@ -0,0 +1,210 @@
+---
+title: Collecting Custom Metrics with Database Monitoring
+description: Use the custom_queries option to collect metrics from your own database tables.
+further_reading:
+- link: "/database_monitoring/"
+  tag: "Documentation"
+  text: "Database Monitoring"
+- link: "/metrics/types/"
+  tag: "Documentation"
+  text: "Metric Types"
+---
+
+Use `custom_queries` to collect metrics from any table the Agent's database user can read. This extends the data available in Datadog beyond the query performance metrics that Database Monitoring collects natively, such as application state tables, business counters, or queue depths.
+
+## Before you begin
+
+The Datadog Agent must be installed and the database integration configured. The Agent's database user needs `SELECT` on any tables you query.
+
+## Configuration
+
+Add `custom_queries` to your integration's `conf.yaml` file. Each entry in the list runs one SQL query and maps its output columns to metrics or tags.
+
+| Option | Required | Description |
+| --- | --- | --- |
+| `metric_prefix` | Yes | All metrics emitted by this query begin with this prefix. |
+| `query` | Yes | The SQL to execute. All returned rows are evaluated. Use the pipe character (`\|`) for multi-line queries. |
+| `columns` | Yes | A list of columns in the same order as your `SELECT`. Each column requires a `name` and a `type`. Set `type` to `gauge`, `count`, `rate`, or another [metric type][1] to emit a metric, or `tag` to apply the column value as a tag on every metric from this query. |
+| `tags` | No | A list of static tags applied to every metric from this query. |
+
+**Notes:**
+- The number of `columns` entries must equal the number of columns returned by the query.
+- The order of `columns` entries must match the order of columns returned by the query.
+- At least one entry in `columns` must be a metric type (not `tag`).
+
+## Examples
+
+{{< tabs >}}
+{{% tab "PostgreSQL" %}}
+
+Add `custom_queries` to your `postgres.d/conf.yaml` file.
+
+If the query reads from a table the `datadog` user cannot already access, grant the permission first:
+
+```sql
+GRANT SELECT ON <TABLE_NAME> TO datadog;
+```
+
+**Example:** The following `company` table contains employee records:
+
+```text
+id | name  | age | address    | salary
+---------------------------------------
+1  | Paul  | 32  | California | 20000
+2  | Allen | 25  | Texas      | 30000
+3  | Teddy | 23  | Norway     | 45000
+```
+
+To collect `age` and `salary` as metrics with `name` and `address` as tags:
+
+```yaml
+custom_queries:
+  - metric_prefix: postgresql.employee
+    query: SELECT age, salary, name, address FROM company
+    columns:
+      - name: employee_age
+        type: gauge
+      - name: employee_salary
+        type: gauge
+      - name: name
+        type: tag
+      - name: address
+        type: tag
+    tags:
+      - source:hr_db
+```
+
+After you update the file, [restart the Agent][2].
+
+For the full configuration reference, see [Postgres Custom Metric Collection][3].
+
+[2]: /agent/configuration/agent-commands/#restart-the-agent
+[3]: /integrations/faq/postgres-custom-metric-collection-explained/
+{{% /tab %}}
+
+{{% tab "MySQL" %}}
+
+Add `custom_queries` to your `mysql.d/conf.yaml` file.
+
+**Important:** All table references must include the database name (`database_name.table_name`). If you omit the database name, the Agent fails with the error: `No database selected`.
+
+**Example:** The following `company` table in the `testdb` database contains employee records:
+
+```text
+id | name  | age | address    | salary
+---------------------------------------
+1  | Paul  | 32  | California | 20000
+2  | Allen | 25  | Texas      | 30000
+3  | Teddy | 23  | Norway     | 45000
+```
+
+To collect `age` and `salary` as metrics with `name` and `address` as tags:
+
+```yaml
+custom_queries:
+  - metric_prefix: mysql.employee
+    query: SELECT age, salary, name, address FROM testdb.company
+    columns:
+      - name: employee_age
+        type: gauge
+      - name: employee_salary
+        type: gauge
+      - name: name
+        type: tag
+      - name: address
+        type: tag
+    tags:
+      - source:hr_db
+```
+
+After you update the file, [restart the Agent][2].
+
+For the full configuration reference, see [MySQL Custom Queries][3].
+
+[2]: /agent/configuration/agent-commands/#restart-the-agent
+[3]: /integrations/guide/mysql-custom-queries/
+{{% /tab %}}
+
+{{% tab "SQL Server" %}}
+
+SQL Server supports two approaches for collecting custom metrics: [custom queries](#custom-queries) or [performance counters](#performance-counters).
+
+### Custom queries
+
+Add `custom_queries` to your `sqlserver.d/conf.yaml` file to collect metrics from any table.
+
+**Example:** The following `company` table in `testdb` contains employee records:
+
+```text
+id | name  | age | address    | salary
+---------------------------------------
+1  | Paul  | 32  | California | 20000
+2  | Allen | 25  | Texas      | 30000
+3  | Teddy | 23  | Norway     | 45000
+```
+
+To collect `age` and `salary` as metrics with `name` and `address` as tags:
+
+```yaml
+custom_queries:
+  - metric_prefix: sqlserver.employee
+    query: SELECT age, salary, name, address FROM testdb.dbo.company
+    columns:
+      - name: employee_age
+        type: gauge
+      - name: employee_salary
+        type: gauge
+      - name: name
+        type: tag
+      - name: address
+        type: tag
+    tags:
+      - source:hr_db
+```
+
+### Performance counters
+
+Use `custom_metrics` to collect metrics from `sys.dm_os_performance_counters` and other system DMVs.
+
+```yaml
+custom_metrics:
+  - name: sqlserver.clr.execution
+    counter_name: CLR Execution
+```
+
+| Option | Required | Description |
+| --- | --- | --- |
+| `name` | Yes | The metric name in Datadog. |
+| `counter_name` | Yes | The counter name from `sys.dm_os_performance_counters`. |
+| `instance_name` | No | A specific counter instance. Use `ALL` to collect all instances (requires `tag_by`). |
+| `tag_by` | No | Tag name used to differentiate instances when `instance_name: ALL`. |
+
+After you update the file, [restart the Agent][2].
+
+For the full configuration reference, including performance counter details and the legacy stored procedure method, see [Collect SQL Server Custom Metrics][3].
+
+[2]: /agent/configuration/agent-commands/#restart-the-agent
+[3]: /integrations/guide/collect-sql-server-custom-metrics/
+{{% /tab %}}
+{{< /tabs >}}
+
+## Validation
+
+After the Agent runs, search for your metrics in the [Metrics Explorer][4].
+
+To check for configuration errors, [run the Agent's status subcommand][5] and look for your integration under the Checks section:
+
+```text
+postgres
+--------
+  - instance #0 [ERROR]: 'Missing metric_prefix parameter in custom_queries'
+  - Collected 0 metrics, 0 events & 0 service checks
+```
+
+## Further Reading
+
+{{< partial name="whats-next/whats-next.html" >}}
+
+[1]: /metrics/types/
+[4]: /metrics/explorer/
+[5]: /agent/configuration/agent-commands/#agent-status-and-information

content/en/database_monitoring/custom_metrics/exploring_custom_metrics.md

@@ -0,0 +1,108 @@
+---
+title: Exploring Custom Metrics
+description: Explore timeseries graphs for custom queries on the database instance detail page.
+further_reading:
+- link: "/database_monitoring/custom_metrics/"
+  tag: "Documentation"
+  text: "Collecting Custom Metrics with Database Monitoring"
+- link: "/database_monitoring/"
+  tag: "Documentation"
+  text: "Database Monitoring"
+---
+
+The **Custom Metrics** section appears on the database instance detail page and displays timeseries graphs for any custom queries you have defined in your Datadog Agent configuration.
+
+## Overview
+
+If you have configured `custom_queries` in your Datadog Agent's database integration, this section automatically discovers those queries and visualizes each metric column as a timeseries graph. This lets you monitor business-specific or environment-specific database metrics alongside the standard Database Monitoring metrics, all in one place.
+
+## How it works
+
+1. Define custom queries in your Agent config. Each query specifies:
+- A SQL statement
+- One or more metric columns (with types like `gauge`, `count`, or `rate`)
+- Optional tag columns
+- An optional metric prefix
+- An optional collection interval
+2. The Agent collects the metrics by running your SQL queries on the configured interval (default: every 15 seconds) and emitting the results as Datadog metrics.
+3. The Custom Metrics section displays a graph for each metric column from your custom queries, scoped to the current database instance. Metrics are named `<prefix>.<column_name>` (for example, `postgresql.my_table_row_count`).
+
+## Example Agent configuration
+
+The following PostgreSQL example tracks table size and row counts per table:
+
+```yaml
+init_config:
+
+instances:
+  - dbm: true
+    host: localhost
+    port: 5432
+    username: datadog
+    password: <PASSWORD>
+    custom_queries:
+      - metric_prefix: postgresql.custom
+        query: |
+          SELECT
+            table_name,
+            pg_total_relation_size(quote_ident(table_name)) AS total_bytes,
+            n_live_tup                                       AS live_rows,
+            n_dead_tup                                       AS dead_rows
+          FROM information_schema.tables
+          JOIN pg_stat_user_tables USING (table_name)
+          WHERE table_schema = 'public'
+        columns:
+          - name: table_name
+            type: tag
+          - name: total_bytes
+            type: gauge
+          - name: live_rows
+            type: gauge
+          - name: dead_rows
+            type: gauge
+        collection_interval: 60
+        tags:
+          - env:production
+          - service:my-app
+```
+
+This configuration produces three metrics, each broken down by `table_name`:
+
+- `postgresql.custom.total_bytes`
+- `postgresql.custom.live_rows`
+- `postgresql.custom.dead_rows`
+
+All three appear as separate timeseries graphs in the Custom Metrics section of the instance detail page.
+
+## Column types
+
+Each column in a custom query is assigned a type that controls how the metric is aggregated and displayed:
+
+| Type | Description |
+| --- | --- |
+| `gauge` | A value that can go up or down (for example, table size). |
+| `count` | A count of events since the last collection. |
+| `rate` | A per-second rate. |
+| `monotonic_count` | A counter that only increases. |
+| `monotonic_gauge` | A monotonically increasing gauge. |
+| `temporal_percent` | A percentage of time. |
+| `time_elapsed` | Duration in time units. |
+| `tag` | Groups or filters metrics; not plotted as its own graph. |
+
+`count` and `monotonic_count` columns are aggregated as `sum`. All other metric types are aggregated as `avg`.
+
+## Viewing the source SQL
+
+Each graph has a **View SQL query** button in the top-right corner. Clicking it shows the raw SQL statement that produces the metric, so you can understand and audit what is being measured.
+
+## Collection interval
+
+The section subtitle shows how often the metrics are collected (for example, "collected every 15s"). If you have multiple custom queries with different intervals, the range is shown (for example, "collected every 15s–60s").
+
+## Requirements
+
+Custom queries must be defined under the `custom_queries` key in the database integration configuration. The Custom Metrics section is hidden if no custom queries are configured.
+
+## Further Reading
+
+{{< partial name="whats-next/whats-next.html" >}}