[Bug]: aggregate_records (MCP) generates an invalid default ORDER BY SUM(<raw column>) against the grouped derived table on dwsql (Microsoft Fabric Warehouse) → Invalid column name #3695

What happened?

Summary

When calling the MCP aggregate_records tool with a numeric aggregate (sum/avg/min/max) plus groupby against a dwsql data source (Microsoft Fabric Warehouse), DAB emits a query whose outer default ORDER BY re-applies the aggregate over the pre-aggregation raw column (e.g. ORDER BY SUM([alias].[amount]) DESC). The outer query's FROM is the grouped derived table, which only exposes the group-by columns and the aliased aggregate ([sum_amount]), not the raw column [amount]. SQL Server therefore fails name resolution with:

Msg 207, Level 16, State 1: Invalid column name 'amount'.

The inner grouped subquery is correct; only the auto-generated outer ORDER BY is wrong. As a result, sum/avg aggregations via MCP are unusable on Fabric Warehouse.

Environment

• Data API builder: 2.0.9 (Microsoft.DataApiBuilder 2.0.9) — also reproduced on 2.0.8
• Data source database-type: dwsql
• Backend: Microsoft Fabric Warehouse (SQL analytics endpoint, *.datawarehouse.fabric.microsoft.com)
• Surface: MCP SQL Server (runtime.mcp), tool aggregate_records
• Entity: a view (dbo.my_view) with key-fields defined
• OS: Windows 11

Configuration (relevant excerpt)

All object names, column names, and connection-string names below are synthetic and minimized for reproduction. The permission setting is also a minimal sample for reproduction only.

{
  "data-source": {
    "database-type": "dwsql",
    "connection-string": "@env('my-connection-string')",
    "options": { "set-session-context": false }
  },
  "runtime": {
    "mcp": {
      "enabled": true,
      "path": "/mcp",
      "dml-tools": {
        "describe-entities": true,
        "read-records": true,
        "aggregate-records": true
      }
    }
  },
  "entities": {
    "my_view": {
      "source": { "object": "dbo.my_view", "type": "view", "key-fields": ["id"] },
      "permissions": [ { "role": "anonymous", "actions": [ { "action": "read" } ] } ]
    }
  }
}

Repro steps

1. Point DAB (database-type: dwsql) at a Fabric Warehouse and expose a view with a numeric column (here amount) and a string column (category).
2. Start DAB: dab start --LogLevel Debug.
3. Call the MCP aggregate_records tool:

{
  "method": "tools/call",
  "params": {
    "name": "aggregate_records",
    "arguments": {
      "entity": "my_view",
      "function": "sum",
      "field": "amount",
      "groupby": ["category"]
    }
  }
}

4. The call fails with InternalServerError: Invalid column name 'amount'.

Note: passing an explicit orderby (e.g. ["category asc"]) does not change the generated SQL — the broken default ORDER BY SUM(<raw column>) DESC is still emitted, so there is no client-side workaround.

Actual generated SQL (from --LogLevel Debug)

SELECT COALESCE('['+STRING_AGG('{'+N'"category":' + ISNULL('"'+STRING_ESCAPE([category],'json')+'"','null')+', '+N'"sum_amount":' + ISNULL(STRING_ESCAPE(CONVERT(NVARCHAR(MAX), [sum_amount]),'json'),'null')+'}',', ')+']','[]')
FROM (
    SELECT TOP 101
        [dbo_my_view].[category] AS [category],
        sum([dbo_my_view].[amount]) AS [sum_amount]
    FROM [dbo].[my_view] AS [dbo_my_view]
    WHERE 1 = 1
    GROUP BY [dbo_my_view].[category]
) AS [dbo_my_view]
ORDER BY SUM([dbo_my_view].[amount]) DESC   -- <-- invalid: [amount] is not a column of the derived table

The derived table aliased [dbo_my_view] only exposes [category] and [sum_amount]. The outer ORDER BY SUM([dbo_my_view].[amount]) references the raw, pre-aggregation column [amount], which does not exist at that scope → Invalid column name 'amount'.

Expected behavior

The default ordering should reference the projected aggregate alias, not re-aggregate the raw column in the outer scope:

) AS [dbo_my_view]
ORDER BY [sum_amount] DESC

(Equivalently, DAB should either order by the aliased aggregation output or omit the default ORDER BY when the client did not request one.)

Additional context / scoping

• read_records on the same entity and the same column (SELECT amount ...) works correctly — the column and permissions are fine.
• aggregate_records with function: "count", field: "*" works (it does not reference a raw measure column).
• Only the numeric aggregates (sum/avg/min/max) with groupby fail, and the failure is entirely in the auto-generated outer ORDER BY.
• Running the intended query by hand against the Warehouse (grouped subquery + ORDER BY [sum_amount]) succeeds, confirming the issue is the generated SQL, not the data/schema/permissions.
• This looks related to the dwsql query builder's default order-by generation for aggregations (cf. previous fix "failing MCP aggregate_records tool caused by groupby default value", [MCP] Bug-fix- aggregate_records always requires groupby #3294).

Error detail

fail: Azure.DataApiBuilder.Core.Resolvers.IQueryExecutor[0]
      Query execution error due to:
Invalid column name 'amount'.
Microsoft.Data.SqlClient.SqlException (0x80131904): Invalid column name 'amount'.
   at Azure.DataApiBuilder.Core.Resolvers.QueryExecutor`1.ExecuteQueryAgainstDbAsync[TResult](...) in /_/src/Core/Resolvers/QueryExecutor.cs:line 296
Error Number: 207, State: 1, Class: 16

Version

2.0.9

What database are you using?

Azure SQL （dwsql（Microsoft Fabric Warehouse））

What hosting model are you using?

Local (including CLI)

Which API approach are you accessing DAB through?

MCP

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