LanceSchemaHelper.java

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package org.apache.doris.datasource.lance.metadata;

import org.apache.doris.catalog.Column;

import org.apache.arrow.vector.types.pojo.Field;
import org.apache.arrow.vector.types.pojo.Schema;

import java.util.ArrayList;
import java.util.List;

/** Shared Arrow-to-Doris column construction for catalog schemas and search TVFs. */
public final class LanceSchemaHelper {
    private LanceSchemaHelper() {
    }

    /** Returns fresh mutable columns; column positions are ordinals, not Lance field IDs. */
    public static List<Column> toDorisColumns(Schema schema) {
        List<Column> columns = new ArrayList<>(schema.getFields().size());
        int position = 0;
        for (Field field : schema.getFields()) {
            columns.add(toDorisColumn(field, position++));
        }
        return columns;
    }

    /** Preserves Arrow nullability and comments while assigning the Doris schema position. */
    public static Column toDorisColumn(Field field, int position) {
        String comment = field.getMetadata() == null ? null : field.getMetadata().get("comment");
        return new Column(field.getName(), LanceTypeConverter.toDorisType(field), false,
                null, field.isNullable(), comment, true, position);
    }

}