How to fix Error 494 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 494 – “TABLESAMPLE Clause Can Only Be Used With Local Tables”

Why This Error Happens

This error occurs when the TABLESAMPLE clause is applied to a remote table, a linked server object, a view, or a derived table/subquery instead of a local base table. SQL Server 2025’s query engine restricts TABLESAMPLE to physical, local tables because the sampling mechanism relies on reading data pages directly from local storage, which isn’t possible through a linked server connection or a virtualized object like a view. This typically surfaces when developers migrate queries that reference four-part names (Server.Database.Schema.Table) or attempt to sample from a CTE.

Step-by-Step Resolution Guide

Step 1: Identify the Non-Local Object in the Query

  • Review the query and locate every instance of TABLESAMPLE in the FROM clause.
  • Check if the table reference uses a four-part name (e.g., LinkedServer.DB.dbo.Table) indicating a linked server.
  • Confirm whether TABLESAMPLE is being applied to a view, CTE, or derived table rather than a base table using SSMS’s “Object Explorer.”

Step 2: Refactor the Query to Use a Local Table Reference

  • Rewrite the query to pull data into a local staging table first using SELECT INTO #TempTable FROM LinkedServer.DB.dbo.Table.
  • Apply TABLESAMPLE to the local temporary or staging table instead: SELECT * FROM #TempTable TABLESAMPLE (10 PERCENT).
  • If sampling a view, redirect the TABLESAMPLE clause to the underlying base table(s) referenced by the view definition.

Step 3: Validate Linked Server and Synonym Configurations

  • Open SSMS, navigate to Server Objects > Linked Servers, and confirm the object is indeed remote.
  • Check for synonyms via sys.synonyms that might be masking a remote object as if it were local: run SELECT * FROM sys.synonyms WHERE name = 'YourObjectName';.
  • If a synonym points to a linked server, drop it and replace direct references with the staging table approach from Step 2.

Step 4: Update Application or ORM-Generated Queries

  • If the query is auto-generated (e.g., by Entity Framework or a reporting tool), locate the query template in the application’s data access layer.
  • Modify the template logic to avoid applying TABLESAMPLE to computed or remote data sources.
  • Redeploy the updated application build and clear any cached query plans using DBCC FREEPROCCACHE;.

Alternative or Verification Steps

  • Run the corrected query in SSMS and confirm Error 494 no longer appears in the Messages tab; check sys.dm_exec_query_stats to ensure the query compiles successfully.
  • As an alternative, replace TABLESAMPLE with a manual sampling technique using ORDER BY NEWID() combined with TOP (n) when working with remote or view-based datasets that cannot be staged locally.