How to fix Error 11440 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: Error 11440 — ALTER TABLE SWITCH Failure Due to Ordered Clustered Columnstore Index Mismatch

Why This Error Happens

This error occurs because SQL Server 2025 requires both the source and target tables in a partition SWITCH operation to have matching ordered clustered columnstore index (CCI) configurations. When one table has an ordered clustered columnstore index defined (using the new ORDER clause) and the other table uses a standard or unordered clustered columnstore index, the schema metadata between the two tables is considered incompatible. SQL Server blocks the SWITCH operation to prevent data integrity issues, since the physical row-group ordering guarantees cannot be preserved across mismatched index structures.

Step-by-Step Resolution Guide

Step 1: Verify the Index Definitions on Both Tables

  • Run the following query to inspect the columnstore index metadata for both the source and target tables:
SELECT t.name AS TableName, i.name AS IndexName, i.type_desc, i.index_id
FROM sys.indexes i
JOIN sys.tables t ON i.object_id = t.object_id
WHERE t.name IN ('SourceTable', 'TargetTable');
  • Check the sys.index_columns and sys.columns catalog views to confirm whether an ORDER clause was applied.
  • Note which table has the ordered clustered columnstore index and which does not.

Step 2: Recreate the Mismatched Index with Matching Order Configuration

  • Drop the non-ordered clustered columnstore index on the table that lacks ordering:
DROP INDEX IF EXISTS CCI_TargetTable ON dbo.TargetTable;
  • Recreate it as an ordered clustered columnstore index, matching the column order used on the source table:
CREATE CLUSTERED COLUMNSTORE INDEX CCI_TargetTable
ON dbo.TargetTable
ORDER (ColumnA, ColumnB);
  • Ensure the column order exactly matches the ordering key used on the opposite table involved in the SWITCH.

Step 3: Rebuild and Validate Table Schema Consistency

  • Rebuild both indexes to ensure row groups are physically reorganized according to the new order:
ALTER INDEX CCI_TargetTable ON dbo.TargetTable REBUILD;
  • Confirm that both tables now share identical partitioning schemes, file group alignment, and columnstore ordering definitions.
  • Re-run the ALTER TABLE ... SWITCH statement to test if the error persists.

Step 4: Check Partition Function and Scheme Alignment

  • Validate that both tables use the same partition function and partition scheme, since SWITCH operations also fail silently if partitions misalign in addition to index mismatches.
  • Query sys.partition_functions and sys.partition_schemes to confirm alignment between source and target tables.

Alternative or Verification Steps

  • After applying the fix, execute the ALTER TABLE SWITCH command again in a test/staging environment first; a successful completion without Error 11440 confirms the index structures are now compatible.
  • If recreating the index is not feasible due to size or downtime constraints, consider using CREATE TABLE AS SELECT (CTAS) with the matching ordered CCI definition to rebuild the target table from scratch, then perform the switch against the newly created table.