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Warehouse challenge — 5 Isolated MCP Servers (Level 5)

Five separate, read-only local DuckDB data warehouses (synthetic Jaffle Shop data), each surfaced behind its own streamable-HTTP MCP server. Connect your coding agent or custom harness to compare multi-source MCP querying against A2A delegation.

How this sandbox works:

1. Physical isolation: Each table lives in its own locked, read-only DuckDB file (orders.duckdb, stores.duckdb, customers.duckdb, order_items.duckdb, products.duckdb). Cross-table SQL JOIN, CTE, or UNION queries at a source are rejected.

2. Paging & simulated distance: Every source returns at most 500 rows per page (pass page=2, 3, ... while more: true) and adds a 100 ms simulated network delay per call. Money columns (subtotal, tax_paid, order_total, price) are in integer cents.

3. Zero-load & durable telemetry: Refreshing this page reads /metrics.json from in-memory atomic counters in <1 ms (hydrated from BigQuery on cold start and streamed asynchronously on every MCP call) so page reloads never touch DuckDB or run BigQuery queries.

Live MCP Telemetry

Total MCP Calls
0
All-time (BigQuery-backed)
Calls (Last 7 Days)
0
Rolling 7-day UTC window
Calls (Last 24 Hours)
0
Rolling 24-hour window
Rejected / Errors
0
SQL rule violations blocked

5 Isolated Data Warehouses & MCP Endpoints

Machine-readable catalog: /catalog.json · Live metrics JSON: /metrics.json

MCP Server Isolated Warehouse Cols Rows Streamable-HTTP Endpoint Tools Total Calls 7d Calls Avg ms

Schema & Join Keys Across Warehouses

WarehouseKey Columns & RelationshipsNotes
orders.duckdbid (PK), customer → customers.id, store_id → stores.id, ordered_at, subtotal, tax_paid, order_total66,375 rows · 2018-09-01 to 2021-08-30 · cents
stores.duckdbid (PK), name, opened_at, tax_rate6 stores (Philadelphia, Brooklyn, Chicago, San Francisco, New Orleans, ...)
customers.duckdbid (PK), name2,583 customers (81 share a name; group by id, not name)
order_items.duckdbid (PK), order_id → orders.id, sku → products.sku99,753 line items
products.duckdbsku (PK), name, type (jaffle / beverage), price, description10 products · price in cents

Quick Connect (Gemini CLI / Claude Code / Antigravity / MCP Inspector)

{
  "mcpServers": {
    "warehouse-orders":      { "type": "http", "url": "https://msampathkumar.com/demos/data-warehouse/orders/" },
    "warehouse-stores":      { "type": "http", "url": "https://msampathkumar.com/demos/data-warehouse/stores/" },
    "warehouse-customers":   { "type": "http", "url": "https://msampathkumar.com/demos/data-warehouse/customers/" },
    "warehouse-order_items": { "type": "http", "url": "https://msampathkumar.com/demos/data-warehouse/order_items/" },
    "warehouse-products":    { "type": "http", "url": "https://msampathkumar.com/demos/data-warehouse/products/" }
  }
}

Challenge Questions (0)

#LevelQuestionWarehouses Needed