Package com.amazonaws.athena.connector.substrait.util

Class LimitAndSortHelper

java.lang.Object

com.amazonaws.athena.connector.substrait.util.LimitAndSortHelper

public final class LimitAndSortHelper
extends Object

Utility class that extracts LIMIT and ORDER BY information from Substrait plans to enable pushdown of these operations to the underlying data source.

This helper parses Plan objects to extract:

• LIMIT values from FetchRel nodes, falling back to Constraints when no plan is available
• ORDER BY sort fields from SortRel nodes, mapped to column names via table metadata

Connectors can use the extracted LimitAndSortHelper.GenericSortField representations to build data-source-specific sort clauses (e.g., MongoDB sort documents, SQL ORDER BY clauses).

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	LimitAndSortHelper.GenericSortField	A data-source-agnostic representation of a sort field, containing the column name and sort direction.

Method Summary

Modifier and Type	Method	Description
static Optional<Integer>	getLimit(io.substrait.proto.Plan plan, Constraints constraints)	Determines if a LIMIT can be applied and extracts the limit value.
static Optional<List<LimitAndSortHelper.GenericSortField>>	getSortFromPlan(io.substrait.proto.Plan plan)	Extracts sort field information from a Substrait plan for ORDER BY pushdown.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getLimit

public static Optional<Integer> getLimit(io.substrait.proto.Plan plan,
                                         Constraints constraints)

Determines if a LIMIT can be applied and extracts the limit value.

When a Substrait Plan is provided, the limit is extracted from its FetchRel node. Otherwise, falls back to the limit defined in Constraints.

Parameters:

plan - the Substrait plan to extract the limit from, or null to use constraints

constraints - the query constraints containing a fallback limit value

Returns:

an Optional containing the limit value if one can be applied, or empty otherwise

getSortFromPlan

public static Optional<List<LimitAndSortHelper.GenericSortField>> getSortFromPlan(io.substrait.proto.Plan plan)

Extracts sort field information from a Substrait plan for ORDER BY pushdown.

Parses the SortRel node in the plan to produce a list of LimitAndSortHelper.GenericSortField objects, each containing a column name and sort direction. If the plan is null, has no relations, or contains no sort relation, returns empty.

Parameters:

plan - the Substrait plan to extract sort information from, or null

Returns:

an Optional containing the list of sort fields, or empty if no sort is present