pg_upsert

Insert a row or update if it already exists (INSERT ... ON CONFLICT DO UPDATE). Specify conflict columns for uniqueness check. Use data or values for column-value pairs.

SERVERPostgreSQL MCP Server SOURCE@neverinfamous/postgres-mcp

Medium RISK CLASS

Category Write

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/io-github-neverinfamous-postgres-mcp/pg-upsert.md

WHAT IT DOES

What pg_upsert does on PostgreSQL MCP Server

AI agents use pg_upsert to create or update resources in PostgreSQL MCP Server, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your PostgreSQL MCP Server environment.

RISK

Why pg_upsert is rated Medium

This tool modifies database state by inserting new rows or updating existing ones based on conflict detection. While reversible (can be undone with subsequent operations or transaction rollback), it permanently alters data once committed. It does not delete, execute arbitrary code, or move money, so Write is the appropriate category.

From the tool's definition Tool performs 'INSERT ... ON CONFLICT DO UPDATE', which creates or modifies data reversibly. Description explicitly states 'Insert a row or update if it already exists', confirming write semantics.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs pg_upsert safely

PolicyLayer is an MCP gateway: it sits between your AI agents and PostgreSQL MCP Server, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For pg_upsert, this is the rule to start with:

pg_upsert Rate-limited

pg_upsert stays usable, but capped: an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "pg_upsert": {
      "limits": [
        {
          "counter": "pg_upsert_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect PostgreSQL MCP Server, apply this rule, and every pg_upsert call is checked against it from then on.

FAQ

Questions about pg_upsert

What does the pg_upsert tool do? +

Insert a row or update if it already exists (INSERT ... ON CONFLICT DO UPDATE). Specify conflict columns for uniqueness check. Use data or values for column-value pairs. It is categorised as a Write tool in the PostgreSQL MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on pg_upsert? +

Register the PostgreSQL MCP Server MCP server in PolicyLayer and add a rule for pg_upsert: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches PostgreSQL MCP Server. Nothing to install.

What risk level is pg_upsert? +

pg_upsert is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit pg_upsert? +

Yes. Add a rate_limit block to the pg_upsert rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block pg_upsert completely? +

Set action: deny in the PolicyLayer policy for pg_upsert. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides pg_upsert? +

pg_upsert is provided by the PostgreSQL MCP Server MCP server (@neverinfamous/postgres-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

What pg_upsert does on PostgreSQL MCP Server

Why pg_upsert is rated Medium

The rule that runs pg_upsert safely

Questions about pg_upsert

More on PostgreSQL MCP Server, and thousands of servers like it.