Microsoft Fabric Reference

Reference material for Microsoft Fabric Publishing -- data type mappings, querying, troubleshooting, and CLI arguments.

Data Type Mapping

Source types are mapped to Fabric-compatible Delta Lake types.

PostgreSQL to Fabric

PostgreSQL Type	Delta Lake Type
INTEGER, INT4	INT
BIGINT, INT8	BIGINT
SMALLINT, INT2	SMALLINT
NUMERIC(p,s)	DECIMAL(p,s)
REAL, FLOAT4	FLOAT
DOUBLE PRECISION	DOUBLE
VARCHAR(n), TEXT	STRING
DATE	DATE
TIMESTAMP	TIMESTAMP
TIMESTAMPTZ	TIMESTAMP
BOOLEAN	BOOLEAN
BYTEA	BINARY

SQL Server to Fabric

SQL Server Type	Delta Lake Type
INT	INT
BIGINT	BIGINT
SMALLINT	SMALLINT
TINYINT	TINYINT
DECIMAL(p,s)	DECIMAL(p,s)
FLOAT	DOUBLE
REAL	FLOAT
VARCHAR(n), NVARCHAR(n)	STRING
DATE	DATE
DATETIME, DATETIME2	TIMESTAMP
DATETIMEOFFSET	TIMESTAMP
BIT	BOOLEAN
VARBINARY	BINARY

Querying Tables

SQL Analytics Endpoint

-- Query a Delta table
SELECT * FROM your_lakehouse.dbo.customer LIMIT 10;

-- Aggregation
SELECT
    c_nationkey,
    COUNT(*) as customer_count,
    SUM(c_acctbal) as total_balance
FROM your_lakehouse.dbo.customer
GROUP BY c_nationkey
ORDER BY customer_count DESC;

Spark Notebooks

# Read a Delta table
df = spark.read.table("customer")
df.show(10)

# Query with SQL
spark.sql("""
    SELECT c_nationkey, COUNT(*) as cnt
    FROM customer
    GROUP BY c_nationkey
""").show()

# Write results back
result_df.write.mode("overwrite").saveAsTable("customer_summary")

Troubleshooting

Common Issues

Authentication Errors

Error: AADSTS7000215: Invalid client secret provided

Regenerate your client secret in Azure AD and update credentials.json.

Error: The user or service principal does not have access to the workspace

1. Verify the Service Principal is added to the workspace
2. Ensure it has Member or Contributor role
3. Wait a few minutes for permissions to propagate

OneLake Connection Issues

Error: Unable to connect to OneLake storage

1. Verify the directory format: onelake://workspace-name/lakehouse-name/
2. Check that the Service Principal has Storage Blob Data Contributor role
3. Ensure workspace and lakehouse names are correct (case-sensitive)

Table Creation Failures

Error: Failed to create table in Lakehouse

1. Verify the SQL analytics endpoint is correct
2. Check that the Lakehouse is active (not paused)
3. Ensure sufficient capacity units are available
4. Confirm Parquet files were exported to OneLake

SQL Endpoint Connection Issues

Error: Cannot connect to SQL analytics endpoint

1. Verify the SQL endpoint hostname
2. Ensure the SQL analytics endpoint is enabled
3. Check firewall rules if connecting from on-premises

Verifying Export Success

Check files in OneLake:

1. Open your Lakehouse in Fabric portal
2. Go to the Files section
3. Verify Parquet files exist in the expected folders

Check tables:

1. Open the SQL analytics endpoint
2. Expand Tables in the object explorer
3. Verify your tables appear

Debug Mode

./LakeXpress sync --log_lev DEBUG

CLI Reference

Fabric Publishing Arguments

Option	Type	Description
--publish_target ID	String	Credential ID for Fabric publishing (required)
--publish_method METHOD	Enum	internal (Delta tables) or external (SQL views)
--publish_table_pattern PATTERN	String	Table naming pattern (default: {table})
--n_jobs N	Integer	Parallel workers for table creation (default: 1)

Full Example

./LakeXpress config create \
    -a credentials.json \
    --lxdb_auth_id lxdb_postgres \
    --source_db_auth_id source_postgres \
    --source_db_name tpch \
    --source_schema_name tpch_1 \
    --fastbcp_dir_path ./FastBCP_linux-x64/latest/ \
    --fastbcp_p 2 \
    --n_jobs 4 \
    --target_storage_id onelake_storage \
    --publish_target fabric_lakehouse \
    --publish_method internal \
    --publish_table_pattern "{schema}_{table}" \
    --generate_metadata

./LakeXpress sync

See Also

• Microsoft Fabric Publishing - Setup and usage guide
• Intermediate Storage - OneLake configuration
• CLI Reference - All command-line options