Apache Arrow

2 posts about Apache Arrow. Every summary links to the original.

Ramp · Jul 22, 2026
Apache Arrow Cut Snowflake Fetch Memory Growth by Up to 79%
An ML training run was exhausting worker memory before training could start because a cold Snowflake fetch peaked at 88.8 GiB RSS, versus 17.6 GiB when loading local Parquet. The shared Snowflake-to-pandas path created Python objects and SQLAlchemy Row proxies before pandas built the DataFrame, with temporary representations requiring roughly three times the final DataFrame size at peak. An Apache Arrow path for supported reads reduced median peak process RSS growth by 60–79% across three query shapes, while peak Python allocations fell by 69–87%. The narrow and wide tests also ran faster, but aggregate timing was mixed, so elapsed time was not the headline claim. Existing jobs adopted the default without query rewrites, with normalization preserving the pandas contract and SQLAlchemy retained for unsupported reads; in one workflow, lower fetch peaks doubled the training-data window on the same cluster size.
Dwight Temple
Databricks · May 20, 2026
Introducing Arrow UDFs in PySpark: A Faster, Leaner Replacement for Pandas UDFs
Apache Spark’s Pandas UDFs improve Python UDF throughput through Arrow-based serialization and batching, but Pandas/Arrow conversion can add copies, limit zero-copy behavior, and weaken support for complex datatypes. Native Arrow UDFs, introduced in Databricks Runtime 18.0, operate directly on Arrow data without converting inputs to Pandas or NumPy objects, preserving columnar layout and enabling vectorized processing through Arrow’s compute and memory model. The new @arrow_udf decorator supports scalar, aggregate, and table functions, while type-hinted @udf definitions, mapInArrow, and applyInArrow extend the interface to DataFrame and grouped operations; iterator-based modes can amortize initialization costs. In a comparison, an Arrow UDF ran about 10% faster than a Pandas UDF and used about 40% less memory, with better complex-datatype support.
Ruifeng Zheng, Yicong Huang

Apache Arrow Cut Snowflake Fetch Memory Growth by Up to 79%

An ML training run was exhausting worker memory before training could start because a cold Snowflake fetch peaked at 88.8 GiB RSS, versus 17.6 GiB when loading local Parquet. The shared Snowflake-to-pandas path created Python objects and SQLAlchemy Row proxies before pandas built the DataFrame, with temporary representations requiring roughly three times the final DataFrame size at peak. An Apache Arrow path for supported reads reduced median peak process RSS growth by 60–79% across three query shapes, while peak Python allocations fell by 69–87%. The narrow and wide tests also ran faster, but aggregate timing was mixed, so elapsed time was not the headline claim. Existing jobs adopted the default without query rewrites, with normalization preserving the pandas contract and SQLAlchemy retained for unsupported reads; in one workflow, lower fetch peaks doubled the training-data window on the same cluster size.

Dwight Temple

Introducing Arrow UDFs in PySpark: A Faster, Leaner Replacement for Pandas UDFs

Apache Spark’s Pandas UDFs improve Python UDF throughput through Arrow-based serialization and batching, but Pandas/Arrow conversion can add copies, limit zero-copy behavior, and weaken support for complex datatypes. Native Arrow UDFs, introduced in Databricks Runtime 18.0, operate directly on Arrow data without converting inputs to Pandas or NumPy objects, preserving columnar layout and enabling vectorized processing through Arrow’s compute and memory model. The new @arrow_udf decorator supports scalar, aggregate, and table functions, while type-hinted @udf definitions, mapInArrow, and applyInArrow extend the interface to DataFrame and grouped operations; iterator-based modes can amortize initialization costs. In a comparison, an Arrow UDF ran about 10% faster than a Pandas UDF and used about 40% less memory, with better complex-datatype support.

Ruifeng Zheng, Yicong Huang