Parquet on Ziva

How Trino Pushes Predicates Into Iceberg

Sun, 21 Jun 2026 03:50:00 +0000

What Predicate Pushdown Means In Trino

Predicate pushdown means Trino tries to move part of a WHERE filter closer to the data source. Instead of reading all rows first and filtering only inside the engine, Trino asks the connector whether it can use the predicate while planning or reading the table.

That can reduce work, but it is not one yes/no switch.

The useful mental model is:

pushed down:
  the connector can use the predicate during scan planning or reading

enforced:
  the connector guarantees rows returned by the scan satisfy that predicate

remaining:
  Trino still evaluates the predicate above the scan for correctness

So “pushed down” does not mean “the engine no longer checks it.”

From SQL To Parquet Pages: Tracing An Iceberg Read In Trino

Wed, 17 Jun 2026 03:06:00 +0000

From SQL To Parquet Pages

The read path is where the Trino engine, the Iceberg connector, Iceberg metadata, Parquet files, and Trino Page objects all meet.

The useful way to read this path is not as one long class chain. The useful question is:

Where does the query cross a boundary?

For an Iceberg read, the boundaries are:

Parquet Row Groups, Column Chunks, Pages, And How Trino Reads Them

Tue, 16 Jun 2026 02:39:00 +0000

Parquet is the storage-format layer that sits between Iceberg’s selected data files and Trino’s in-memory execution batches.

For a Trino scan, the useful read shape is:

read file metadata
  -> choose useful row groups
  -> read useful columns
  -> read encoded and compressed Parquet pages
  -> decode batches into Trino blocks
  -> pass Trino Page objects to operators

This note is the storage-format bridge before tracing a real Iceberg read query. The previous note explained how Iceberg metadata points to data files. This one explains what happens after a selected data file is Parquet: how row groups, column chunks, pages, encodings, and Trino Page objects fit together.

Iceberg Table Layout: Avro Metadata And Parquet Data Files

Sun, 14 Jun 2026 03:46:00 +0000

Iceberg Metadata, Avro, And Parquet.