private Column getSplitColumn(Table table) {
        if (table.primaryKeyColumns().isEmpty()) {
            // since we do not need a split column when there is no primary key
            // simply return the first column which won't be used
            return table.columns().get(0);
        } else {
            return ChunkUtils.getSplitColumn(table);
        }
    }
get the split column using primary key
for those don't have primary key, return the first column
@return chunks
inlong-sort/sort-flink/sort-flink-v1.13/sort-connectors/mysql-cdc/src/main/java/org/apache/inlong/sort/cdc/mysql/source/assigners/ChunkSplitter.java