Azure Synapse: Assertion Error while querying view

Question

I am receiving an error sporadically when trying to run any query on views within an azure synapse workspace.

The error is as follows:
[Assertion failed: Number of data blocks does not match number of distinct files. This version of code supports having only one DataBlock per file.]

Is anyone familiar with this issue?

Answer 1

Hello,

I apologize for not checking on this sooner.

This error occurs sporadically but only if a view in synapse is created using a wildcard.

For example:

DROP VIEW IF EXISTS A_View
GO

CREATE VIEW  A_View AS

SELECT *
FROM OPENROWSET('CosmosDB',
                Account= ACCOUNT;Database=DATABASE;Key=KEY',
                A_Table)
AS A_Table

GO

Using the code above will result in "[Assertion failed: Number of data blocks does not match number of distinct files. This version of code supports having only one DataBlock per file.]" when trying to query the view, but not every time you query. It seems to be random.

---

The following resolved my issue:

    DROP VIEW IF EXISTS A_View
    GO

    CREATE VIEW  A_View AS

    SELECT Column1,Column2,Column...
    FROM OPENROWSET('CosmosDB',
                    Account= ACCOUNT;Database=DATABASE;Key=KEY',
                    A_Table)
    AS A_Table

    GO