Hi @Sivagnana Sundaram, Krithiga ,
We got response from product team on the above issue. Kindly have a look:
" Yes, this is the current behavior of Synapse/Polybase: an empty string gets treated as null on export. The upcoming Gen3 DW (ded SQL Pool) will address this which will preview late 2022. Since the fix is non-trivial, there are no plans to fix for current Gen2.
However, a couple options can be done to get unblocked here:
1. When doing CETAS export, convert the empty strings to a unique placeholder value or even an empty space. The round-trip will work and differentiate null vs. empty fields.
CREATE EXTERNAL TABLE [dbo].[abc]
WITH (DATA_SOURCE = [SQLAnalyticsConnectorDataSourceTest1],LOCATION = N'/abc',FILE_FORMAT = [SQLAnalyticsConnectorDefaultFileFormat798e8ca0543342a6b43e0787ab2a7db1])
CASE WHEN name = '' THEN ' ' END AS name
2. Use CSV instead of parquet and specify a STRING_DELIMITER. This will natively support null/empty string differentiation as well without any work-arounds. "
Hope this will help. Please let us know if any further queries.
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