SQL Server Error 16555, Severity 17: "Cannot insert into a columnstore index with unsupported large object types." This error occurs when you attempt to perform an `INSERT` operation on a table that has a columnstore index, but the data being inserted includes columns of unsupported Large Object (LOB) types.
Columnstore indexes are designed for high-performance analytics by storing data in compressed formats, but certain LOB types such as `TEXT`, `NTEXT`, or perhaps even huge `VARCHAR(MAX)`/`NVARCHAR(MAX)` values are not supported. The severity 17, indicating it is related to resource or environment issues rather than general SQL syntax violations.
Common causes:
- Attempting direct inserts into tables with columnstore indexes while including unsupported column/data types.
- Misconfiguration at the schema level (e.g., combining incompatible data types and indexing strategies).
- Usage scenarios where some legacy features conflict with newer functionalities like columnstores.
Understand Unsupported Data Types SQL Server does not allow inserting columns with certain LOB types (`TEXT`, `NTEXT`). Check Microsoft's documentation regarding compatible datatypes for columnstore indexes. Use the query below to identify problematic columns in your table:
SELECT c.name AS ColumnName, t.name AS TypeName, c.max_length AS MaxLength, i.type_desc AS IndexType
FROM sys.columns c
JOIN sys.tables tbl ON c.object_id = tbl.object_id
LEFT JOIN sys.indexes i ON tbl.object_id = i.object_id AND i.type_desc LIKE '%COLUMNSTORE%'
JOIN sys.types t ON c.user_type_id = t.user_type_id
WHERE tbl.name = '<TableName>' AND (t.name IN ('text', 'ntext') OR t.name IN ('varchar', 'nvarchar',etc ))