# PostgreSQL_get_cache_hit_ratio

Get cache hit ratios for tables and indexes.

Agent View of the PolicyLayer registry record for `PostgreSQL_get_cache_hit_ratio`. HTML page: https://policylayer.com/tools/mukul975-postgres-mcp-server/postgresql-get-cache-hit-ratio

## Facts

- Tool: `PostgreSQL_get_cache_hit_ratio`
- Server: Postgres (`mukul975/postgres-mcp-server`) — https://policylayer.com/tools/mukul975-postgres-mcp-server.md
- Homepage: https://github.com/mukul975/postgres-mcp-server
- Risk category: Read (Low risk)
- Registry record: grade F, identity unverified
- Server rate-limited: no
- Parameters: 0
- Recommended policy verdict: Allowed

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "PostgreSQL_get_cache_hit_ratio",
    "arguments": {}
  }
}
```

## Why PostgreSQL_get_cache_hit_ratio is rated Low

This tool queries PostgreSQL cache statistics to return cache hit ratio metrics. It is a read-only diagnostic operation that retrieves existing performance data without creating, modifying, deleting, or executing any changes to the database. The blast radius of misuse is minimal as it cannot alter data or trigger unintended operations.

From the tool's own definition: "Tool name includes 'get' and description states 'Get cache hit ratios' — purely retrieves performance metrics with no modification or side effects."

## Use case

AI agents call PostgreSQL_get_cache_hit_ratio to retrieve information from Postgres without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

## Recommended policy (PolicyLayer)

Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Postgres:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "PostgreSQL_get_cache_hit_ratio": {}
  }
}
```

## Other tools on Postgres (238)

- `PostgreSQL_drop_index` — Destructive — https://policylayer.com/tools/mukul975-postgres-mcp-server/postgresql-drop-index.md
- `PostgreSQL_drop_schema` — Destructive — https://policylayer.com/tools/mukul975-postgres-mcp-server/postgresql-drop-schema.md
- `PostgreSQL_drop_user` — Destructive — https://policylayer.com/tools/mukul975-postgres-mcp-server/postgresql-drop-user.md
- `PostgreSQL_analyze_database` — Execute — https://policylayer.com/tools/mukul975-postgres-mcp-server/postgresql-analyze-database.md
- `PostgreSQL_execute_select_query` — Execute — https://policylayer.com/tools/mukul975-postgres-mcp-server/postgresql-execute-select-query.md
- `PostgreSQL_execute_update_query` — Execute — https://policylayer.com/tools/mukul975-postgres-mcp-server/postgresql-execute-update-query.md
- `PostgreSQL_kill_connection` — Execute — https://policylayer.com/tools/mukul975-postgres-mcp-server/postgresql-kill-connection.md
- `PostgreSQL_refresh_materialized_view` — Execute — https://policylayer.com/tools/mukul975-postgres-mcp-server/postgresql-refresh-materialized-view.md
- `PostgreSQL_vacuum_analyze_table` — Execute — https://policylayer.com/tools/mukul975-postgres-mcp-server/postgresql-vacuum-analyze-table.md
- `analyze_buffer_utilization` — Read — https://policylayer.com/tools/mukul975-postgres-mcp-server/analyze-buffer-utilization.md
- `analyze_foreign_key_locks` — Read — https://policylayer.com/tools/mukul975-postgres-mcp-server/analyze-foreign-key-locks.md
- `analyze_index_effectiveness` — Read — https://policylayer.com/tools/mukul975-postgres-mcp-server/analyze-index-effectiveness.md
- `analyze_query_complexity` — Read — https://policylayer.com/tools/mukul975-postgres-mcp-server/analyze-query-complexity.md
- `analyze_query_plans` — Read — https://policylayer.com/tools/mukul975-postgres-mcp-server/analyze-query-plans.md
- `analyze_sequence_usage` — Read — https://policylayer.com/tools/mukul975-postgres-mcp-server/analyze-sequence-usage.md
- `analyze_transaction_wraparound` — Read — https://policylayer.com/tools/mukul975-postgres-mcp-server/analyze-transaction-wraparound.md
- `analyze_trigger_performance` — Read — https://policylayer.com/tools/mukul975-postgres-mcp-server/analyze-trigger-performance.md
- `analyze_vacuum_efficiency` — Read — https://policylayer.com/tools/mukul975-postgres-mcp-server/analyze-vacuum-efficiency.md
- `check_constraint_violations` — Read — https://policylayer.com/tools/mukul975-postgres-mcp-server/check-constraint-violations.md
- `check_database_encoding_collation` — Read — https://policylayer.com/tools/mukul975-postgres-mcp-server/check-database-encoding-collation.md
- `check_function_performance` — Read — https://policylayer.com/tools/mukul975-postgres-mcp-server/check-function-performance.md
- `check_replication_lag_details` — Read — https://policylayer.com/tools/mukul975-postgres-mcp-server/check-replication-lag-details.md
- `check_table_inheritance` — Read — https://policylayer.com/tools/mukul975-postgres-mcp-server/check-table-inheritance.md
- `monitor_autovacuum_progress` — Read — https://policylayer.com/tools/mukul975-postgres-mcp-server/monitor-autovacuum-progress.md
- `monitor_checkpoint_efficiency` — Read — https://policylayer.com/tools/mukul975-postgres-mcp-server/monitor-checkpoint-efficiency.md
- `monitor_connection_patterns` — Read — https://policylayer.com/tools/mukul975-postgres-mcp-server/monitor-connection-patterns.md
- `monitor_materialized_views` — Read — https://policylayer.com/tools/mukul975-postgres-mcp-server/monitor-materialized-views.md
- `monitor_wal_generation_rate` — Read — https://policylayer.com/tools/mukul975-postgres-mcp-server/monitor-wal-generation-rate.md
- `PostgreSQL_active_temp_file_users` — Read — https://policylayer.com/tools/mukul975-postgres-mcp-server/postgresql-active-temp-file-users.md
- `PostgreSQL_analyze_advanced_buffer_usage` — Read — https://policylayer.com/tools/mukul975-postgres-mcp-server/postgresql-analyze-advanced-buffer-usage.md
- …and 208 more: https://policylayer.com/tools/mukul975-postgres-mcp-server.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=mukul975-postgres-mcp-server · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/mukul975-postgres-mcp-server