# Specification for Advanced PostgreSQL Monitoring

**Track:** Enhance existing database provider for PostgreSQL to support advanced monitoring features.

## 1. Overview

This document outlines the technical specifications for enhancing the existing PostgreSQL database provider to support advanced monitoring capabilities. The primary goal is to expose key performance and health metrics from a connected PostgreSQL instance directly within the LibreDB Studio interface.

## 2. Functional Requirements

-   **FR1: Expose `pg_stat_statements` Data:** The provider must be able to query the `pg_stat_statements` view (if the extension is enabled on the target database) and return a structured representation of the data.
-   **FR2: Expose `pg_stat_activity` Data:** The provider must query the `pg_stat_activity` view to provide real-time information about active connections, their states, and the queries they are executing.
-   **FR3: Expose Index Usage Statistics:** The provider must query `pg_stat_user_indexes` and `pg_stat_user_tables` to provide insights into index usage, including the number of index scans vs. sequential scans.
-   **FR4: Expose Table & Index Bloat:** The provider should include queries to estimate table and index bloat.
-   **FR5: Expose Cache Hit Rate:** The provider must calculate and expose the cache hit rate for indexes and tables.

## 3. Non-Functional Requirements

-   **NFR1: Performance:** All monitoring queries must be designed to have minimal performance impact on the target database. They should be efficient and not lock resources.
-   **NFR2: Error Handling:** The provider must gracefully handle cases where the required extensions (`pg_stat_statements`) are not enabled or the user lacks the necessary permissions to view the statistics tables. It should return a clear message to the user in such cases.
-   **NFR3: Security:** The queries should be read-only and not expose any sensitive data.
-   **NFR4: Data Structure:** The data returned by the provider should be in a well-defined, easily consumable JSON format for the frontend.

## 4. API Endpoint Integration

The new monitoring functionalities will be exposed through a new API endpoint, likely under `/api/db/monitoring/postgres`. This endpoint will accept the connection details and return the collected monitoring data.

## 5. Out of Scope

-   This track does not include the implementation of the frontend components to visualize the monitoring data. It is solely focused on the backend provider and API enhancements.
-   This track will not include any write operations or any actions that modify the database state.
