Implementation:Risingwavelabs Risingwave PkComparator

Metadata

Property	Value
File	java/connector-node/connector-api/src/main/java/com/risingwave/connector/api/PkComparator.java
Language	Java
Module	connector-api
Package	com.risingwave.connector.api
Classes	PkComparator
Lines	43
Interfaces Implemented	Comparator<List<Comparable<Object>>>

Overview

PkComparator implements the Comparator interface for comparing two lists of Comparable values, representing composite primary keys in the RisingWave connector framework. It performs a lexicographic comparison of the primary key columns, checking each column in order and returning the first non-zero comparison result.

If the two primary key lists have different lengths, the comparator throws a gRPC FAILED_PRECONDITION runtime exception, since mismatched primary key lengths indicate a data integrity issue.

Code Reference

Source Location

java/connector-node/connector-api/src/main/java/com/risingwave/connector/api/PkComparator.java

Signature

public class PkComparator implements Comparator<List<Comparable<Object>>> {
    @Override
    public int compare(List<Comparable<Object>> objects1, List<Comparable<Object>> objects2)
}

Imports

import io.grpc.Status;
import java.util.Comparator;
import java.util.List;

I/O Contract

compare

Parameter	Type	Description
objects1	List<Comparable<Object>>	First composite primary key (list of column values)
objects2	List<Comparable<Object>>	Second composite primary key (list of column values)

Direction	Type	Description
Output	int	Negative if objects1 < objects2, zero if equal, positive if objects1 > objects2

Error Handling:

• Throws StatusRuntimeException with FAILED_PRECONDITION status if the two lists have different sizes, indicating a primary key length mismatch.

Algorithm:

1. Verify both lists have the same length
2. Iterate through each column index, comparing corresponding values
3. Return the first non-zero comparison result
4. If all columns are equal, return 0

Usage Examples

// Create a PkComparator instance
PkComparator comparator = new PkComparator();

// Compare two composite primary keys
List<Comparable<Object>> pk1 = Arrays.asList(castToComparable(1), castToComparable("abc"));
List<Comparable<Object>> pk2 = Arrays.asList(castToComparable(1), castToComparable("def"));

int result = comparator.compare(pk1, pk2);
// result < 0 because "abc" < "def"

// Can be used with sorting collections
TreeMap<List<Comparable<Object>>, SinkRow> sortedRows = new TreeMap<>(new PkComparator());

Related Pages

• TableSchema - Provides primary key column information used with PkComparator
• SinkRow Interface - The row interface whose primary key values are compared
• SinkWriterV1 Interface - Sink writers that may use PkComparator for deduplication and upsert logic