@muench-dev/n8n-nodes-postgres

@muench-dev/n8n-nodes-postgres is an n8n community node that adds Postgres checks and metadata lookups that are not covered by the built-in Postgres node.

It is designed for workflows that need to filter incoming items based on database state, detect changes in a tracked column, or inspect schemas, tables, and views directly from PostgreSQL.

Installation Operations Credentials Compatibility Usage Resources Version history

Installation

Follow the n8n community nodes installation guide.

For a self-hosted n8n instance, you can also install the package directly:

npm install @muench-dev/n8n-nodes-postgres

After installation, restart n8n and search for Postgres Extended in the node picker.

Operations

The package currently provides one node: Postgres Extended.

Supported operations:

| Resource | Operation | What it does | | -------- | ------------------- | ------------------------------------------------------------------------- | | Check | Row Exists | Outputs only items for which at least one matching row exists | | Check | Row Does Not Exist | Outputs only items for which no matching row exists | | Check | Row Count Threshold | Outputs only items whose matching row count satisfies a threshold | | Check | Value Has Changed | Outputs only items where a watched column differs from the expected value | | Metadata | List Schemas | Returns database schemas | | Metadata | List Tables | Returns base tables for a selected schema | | Metadata | List Views | Returns views for a selected schema |

Credentials

This package does not ship its own credential type.

Postgres Extended reuses n8n's built-in postgres credential, so you can point it at the same database connections you already use with the core Postgres node.

Typical setup:

1. Create or reuse a standard Postgres credential in n8n.
2. Configure host, port, database, username, password, and SSL settings as needed.
3. Select that credential in Postgres Extended.

The node uses the same connection details supported by the core credential, including SSL-enabled connections.

Compatibility

• Built as an n8n community node package using n8nNodesApiVersion: 1
• Depends on the built-in n8n postgres credential being available
• Best suited for current self-hosted n8n versions that support community nodes and the core Postgres node

If you run an older n8n release and the built-in Postgres credential differs from current n8n behavior, verify the node in a staging environment first.

Usage

Check operations

All check operations work item-by-item. The node evaluates the configured schema, table, and conditions for each incoming item and only forwards items that match the selected rule.

Available condition operators:

• Equal
• Not Equal
• Like
• Greater Than
• Less Than
• Greater Than Or Equal
• Less Than Or Equal
• Is Null
• Is Not Null

You can combine conditions with either:

• All Conditions
• Any Condition

Row Exists

Use this when a workflow item should continue only if a matching row is already present.

Example: continue only if public.users contains a row where email = {{$json.email}}.

Row Does Not Exist

Use this to prevent duplicates.

Example: continue only if public.users does not contain a row where external_id = {{$json.id}}.

Row Count Threshold

This operation compares the number of matching rows against a threshold using one of these comparisons:

• At Least
• More Than
• Exactly
• Less Than
• At Most

When an item matches, the node adds these fields to the output JSON:

• rowCount
• threshold

Value Has Changed

Use this to detect whether a database value is no longer what you expect.

You provide:

• conditions to identify the row
• a Watch Column
• an Expected Value

When the current database value differs from the expected value, the item is forwarded and enriched with:

• currentValue
• expectedValue

This is useful for change detection, status monitoring, and guarding downstream steps.

Metadata operations

Metadata operations ignore item content and return database structure information instead:

• List Schemas returns schemaName
• List Tables returns tableName and schemaName
• List Views returns viewName and schemaName

Notes

• Schema and table names can be selected from n8n resource pickers or entered manually.
• Column options are loaded dynamically from the selected table.
• LIKE supports PostgreSQL wildcard matching such as % and _.
• Value Has Changed requires at least one matching row. If none is found, the node errors unless Continue On Fail is enabled.
• Continue On Fail is supported, so per-item database errors can be emitted as error items instead of failing the whole execution.

Resources

• n8n community nodes documentation
• n8n Postgres node documentation
• PostgreSQL documentation

Version history

0.2.1

Current package version.

Includes:

• Postgres Extended node
• check operations for row existence, row absence, row count thresholds, and value change detection
• metadata operations for schemas, tables, and views