What causes OUT_OF_MEMORY?

A cartesian join (cross join) producing an unexpectedly large intermediate result. A shuffle operation creating too many small partitions or one very large partition (data skew). Collecting a large dataset to the driver with collect() or toPandas(). Broadcasting a large table that exceeds the broadcast threshold. Processing significantly more data than usual due to upstream data growth

How do I fix OUT_OF_MEMORY?

Identify the query step that is consuming the most memory using the Spark UI (look for the stage with the highest memory spill). Check for data skew — if one partition is much larger than others, use salting or repartition. Replace collect() with distributed aggregations and only pull summary results to the driver. Increase the number of shuffle partitions (spark.sql.shuffle.partitions) to reduce per-partition size. Increase the cluster size or switch to a memory-optimized instance type. Enable Spark memory spill to disk as a safety valve (at the cost of performance)

High severitysql

Power BI Refresh Error:
OUT_OF_MEMORY

What does this error mean?

The Databricks cluster ran out of memory while executing a query. The query was consuming more memory than the cluster has available, causing the executor or driver to be killed.

Common causes

1A cartesian join (cross join) producing an unexpectedly large intermediate result
2A shuffle operation creating too many small partitions or one very large partition (data skew)
3Collecting a large dataset to the driver with collect() or toPandas()
4Broadcasting a large table that exceeds the broadcast threshold
5Processing significantly more data than usual due to upstream data growth

How to fix it

1Identify the query step that is consuming the most memory using the Spark UI (look for the stage with the highest memory spill)
2Check for data skew — if one partition is much larger than others, use salting or repartition
3Replace collect() with distributed aggregations and only pull summary results to the driver
4Increase the number of shuffle partitions (spark.sql.shuffle.partitions) to reduce per-partition size
5Increase the cluster size or switch to a memory-optimized instance type
6Enable Spark memory spill to disk as a safety valve (at the cost of performance)

Frequently asked questions

Can I fix OOM without increasing cluster size?

Often yes — query optimization (fixing skew, avoiding cartesian joins, reducing collect() usage) can dramatically reduce memory usage without adding nodes.

What is data skew and how do I detect it?

Data skew occurs when one partition has much more data than others. You can detect it in the Spark UI by looking for a stage where one task takes much longer than the others.