---
title: "Schemas"
description: "Browse PostgreSQL tables, columns, indexes, and constraints collected by Middleware, with table size, scan, and row statistics and the queries that use each table."
section: "APM"
breadcrumb: "APM > Database Monitoring > Schemas"
canonical: "https://docs.middleware.io/features/apm/database-monitoring/schemas"
---
# Schemas

The **Schemas** tab lists the PostgreSQL tables Middleware has collected across your instances, with each table's definition, size, and usage statistics. Use it to check a table's indexes while tuning a slow query, or to compare the same table across databases and hosts.

Schemas are available for **PostgreSQL** only and require **Schema Collection** to be turned on. See [Set Up PostgreSQL](/get-started/database/postgresql).

> **Note:** The Schemas tab always shows the **past day** of schema data. The time picker is disabled while this tab is open, and your previous time range comes back when you leave it.

## Table List

![Schemas tab listing PostgreSQL tables with variants, database, schema and database host](/images/apm/database-monitoring/pg-schemas.png)

| Column | Description |
| --- | --- |
| **Table Name** | Name of the table |
| **Variants** | Number of different definitions found for this table name, for example when the same table has different columns on two hosts |
| **Databases** | Database engine |
| **Schemas** | Schema the table belongs to, such as `public` |
| **Database Hosts** | Instances where the table exists |

Search by table name with the search bar. Expand a row with the arrow to list its variants. Click a **Variant ID** to see that variant's columns and data types.

## Table Details

Click a table to open its details.

![Table details for a PostgreSQL table showing size and row badges and the Definition tab with columns and indexes](/images/apm/database-monitoring/pg-schema-table.png)

The header shows badges for **Table Size**, **Sequential Scans**, **Live Rows**, **Dead Rows**, and **Index Size**. A high sequential scan count on a large table often points to a missing index. Many dead rows compared with live rows can mean autovacuum is falling behind.

| Tab | What it shows |
| --- | --- |
| **Definition** | **Columns** (name, data type, default value, nullable, and the number of instances), **Indexes** (name, definition, size, scan count, and tuples fetched), and **Keys & Constraints** |
| **Variants** | Every variant of this table with its column count |
| **Metrics** | Table size, sequential scans, live and dead rows, index size, index blocks hit, and last autovacuum and autoanalyze time, over the past day |
| **Queries** | [Query Metrics](/features/apm/database-monitoring/query-metrics) filtered to the queries that use this table |

## Schema Explorer

Each PostgreSQL instance also has a **Schema** section on its [Summary](/features/apm/database-monitoring/databases#summary) tab, which shows the schemas of that instance only.

1. Pick a database and schema from the tree on the left, or search with **Search for schema**.
2. Choose a table from **Select table**.
3. Review its **Columns**, **Indexes**, and **Keys & Constraints**.

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