Teradata to Databricks SQL Migration – Common Pitfalls and Fixes

Teradata to Databricks migration is one of the most complex SQL modernization journeys because Teradata SQL contains many platform-specific behaviors that do not directly translate.

This article explains the most common pitfalls and how to fix them safely.

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Why Teradata SQL Is Special

Teradata introduces:

SET vs MULTISET tables
PRIMARY INDEX, UPI, USI
QUALIFY clause
Volatile tables
AMP-based distribution logic

Databricks does not support these concepts directly.

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Pitfall 1 – QUALIFY

Teradata

SELECT *
FROM sales
QUALIFY ROW_NUMBER() OVER (PARTITION BY id ORDER BY dt DESC) = 1;

Databricks

SELECT *
FROM (
  SELECT *, ROW_NUMBER() OVER (PARTITION BY id ORDER BY dt DESC) AS rn
  FROM sales
) t
WHERE rn = 1;

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Pitfall 2 – PRIMARY INDEX

PRIMARY INDEX controls data distribution in Teradata. In Databricks, you must design **partitioning and clustering** manually.

Mapping rule:

| Teradata | Databricks | |--------|-----------| | PI | Partition / ZORDER | | UPI | Partition + uniqueness check | | USI | Secondary indexing strategy |

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Pitfall 3 – Date Arithmetic

Teradata:

CURRENT_DATE - 7

Databricks:

DATE_SUB(CURRENT_DATE(), 7)

Silent mistakes here cause wrong reports.

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Pitfall 4 – MERGE Semantics

Teradata MERGE allows different matching behavior than Delta MERGE. Always validate:

Duplicate match scenarios
Update vs insert precedence
NULL key behavior

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Validation Strategy

Always validate:

Row counts
Aggregation totals
Duplicate detection
Slowly changing dimension logic
Incremental load correctness

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How JarvisX Solves This

JarvisX provides:

Teradata dialect parser
Databricks rewrite engine
Auto-repair for invalid SQL
Validation hooks
Semantic confidence scoring

This reduces migration risk drastically.

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Final Thoughts

Teradata to Databricks migration is not about speed — it is about **accuracy, trust, and long-term maintainability**.

A wrong migration costs more than a slow one.

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**About JarvisX** JarvisX is an AI-powered SQL modernization and validation platform for enterprise data migrations.