Synapse SQL Serverless Pool > Column mapping in DELTA Table

Question

Hello,

Using Azure Synapse, I've loaded a Delta table in azure storage, with column mapping option enabled afterwards (to allow using special characters in column name and renaming function) according to this link:

https://docs.databricks.com/en/delta/delta-column-mapping.html

ALTER TABLE Mytable SET TBLPROPERTIES (
  'delta.minReaderVersion' = '2',
  'delta.minWriterVersion' = '5',
  'delta.columnMapping.mode' = 'name'
)

Then i tried to,query this table from Synapse SQL Serverless Pool using Openrowset, and i've got this error >> Column mapping is not enabled like this one:

**SELECT TOP 10 ***
FROM OPENROWSET(
BULK '...',
DATA_SOURCE = 'SOURCE_ADLS',
FORMAT = 'delta'
) as rows;

This query works fine when option("delta.columnMapping.mode", "name") is not used. When it's used loading directly to a df in a pyspark notebook works fine too.

Answer 1

@Z.K.Z Thanks for using Microsoft Q&A forum and posting your query.

Seems like the error message is misleading at first. But as per the below documentation, Serverless SQL pools in Synapse Analytics are compatible with Delta reader version 1. Whereas the Delta features that require Delta readers with version 2 or higher (for example column mapping) are not supported in the serverless SQL pools.

Ref doc: Troubleshoot Synapse Serverless SQL Pool

As per the column mapping documentation, Column mapping feature requires reader version 2 or above.

Ref doc - Databrics - How to enable Delta Lake column mapping

This is the reason why you are seeing an error while trying to query from Synapse Serverless SQL Pool.
If you have any feedback regarding this feature, please feel free to log it in feedback forum here: https://feedback.azure.com/d365community/forum/9b9ba8e4-0825-ec11-b6e6-000d3a4f07b8

Here is an existing feature request item logged by another user, please feel free to upvote and comment on it to help increase the visibility - Support Delta Column Mapping Mode of Name for Serverless Views

Hope this info helps.

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