Implementation:Lance format Lance Java ZoneMapIndexParams

Knowledge Sources	Lance
Domains	Java_SDK, Indexing
Last Updated	2026-02-08 19:33 GMT

Overview

Description

ZoneMapIndexParams is a final Java class in the org.lance.index.scalar package that provides a builder-style configuration for ZoneMap scalar index parameters. It constructs a ScalarIndexParams instance with the index type set to "zonemap". A zone map index stores min/max statistics per zone (group of rows) to enable fast range-based predicate pushdown. The builder supports a single optional parameter: rowsPerZone, which controls the approximate number of rows in each zone.

Usage

Use ZoneMapIndexParams.builder() to configure zone map index options. The build() method returns a ScalarIndexParams object. The JSON parameters are always serialized (even if empty), using JsonUtils.toJson().

Code Reference

Source Location

java/src/main/java/org/lance/index/scalar/ZoneMapIndexParams.java

Signature

public final class ZoneMapIndexParams {
    public static Builder builder();

    public static final class Builder {
        public Builder rowsPerZone(long rowsPerZone);
        public ScalarIndexParams build();
    }
}

Import

import org.lance.index.scalar.ZoneMapIndexParams;

I/O Contract

Builder Inputs

Parameter	Type	Required	Default	Validation	Description
rowsPerZone	long	No	Not set (Rust default)	Must be positive	Approximate number of rows per zone

Build Output

Return Type	Description
ScalarIndexParams	A scalar index params object with type "zonemap" and JSON configuration

JSON Parameters (serialized internally)

Key	Type	Description
rows_per_zone	long	Approximate number of rows per zone

Usage Examples

import org.lance.index.scalar.ZoneMapIndexParams;
import org.lance.index.scalar.ScalarIndexParams;
import org.lance.index.IndexParams;

// Create a zone map index with default settings
ScalarIndexParams defaultZoneMap = ZoneMapIndexParams.builder().build();

// Create a zone map index with custom rows per zone
ScalarIndexParams customZoneMap = ZoneMapIndexParams.builder()
    .rowsPerZone(8192)
    .build();

// Wrap in IndexParams for use with IndexOptions
IndexParams params = IndexParams.builder()
    .setScalarIndexParams(customZoneMap)
    .build();

Related Pages

• ScalarIndexParams - The output type produced by ZoneMapIndexParams.Builder.build()
• IndexParams - Top-level container that holds scalar index params
• BTreeIndexParams - Another scalar index builder for B-Tree indices
• IndexType - Contains the ZONEMAP enum constant