# Presto 334 Dereference Pushdown for Nested Struct Queries

DevFeed: [Presto 334 Dereference Pushdown for Nested Struct Queries](<https://devfeed.tech/articles/faster-queries-on-nested-data-8648.md>)

Original publisher: [Read original article](<https://trino.io/blog/2020/08/14/dereference-pushdown.html>)

Author: Pratham Desai (LinkedIn), James Taylor (Lyft)

Published: 2020-08-14T00:00:00Z

Content type: article

Language: en

Sources: [Trino Blog](<https://devfeed.tech/sources/trino-blog.md>)

Topics: [Optimization](<https://devfeed.tech/topics/optimization.md>), [data](<https://devfeed.tech/topics/data.md>), [Structured-data](<https://devfeed.tech/topics/structured-data.md>)

Tags: [data](<https://devfeed.tech/tags/data.md>), [data-type](<https://devfeed.tech/tags/data-type.md>), [optimization](<https://devfeed.tech/tags/optimization.md>), [performance](<https://devfeed.tech/tags/performance.md>)

## AI overview

Presto 334 introduces dereference pushdown for queries that access nested fields in struct columns. The optimization prunes structural data early, reducing unnecessary scanning and data shuffling.

## Source excerpt

Presto 334 adds significant performance improvements for queries accessing nested fields inside struct columns. They have been optimized through the pushdown of dereference expressions. With this feature, the query execution prunes structural data eagerly, extracting the necessary fields.