java/kudu-backup/src/main/scala/org/apache/kudu/backup/BackupUtils.scala

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package org.apache.kudu.backup

import org.apache.kudu.Schema
import org.apache.kudu.spark.kudu.SparkUtil
import org.apache.spark.sql.types.ByteType
import org.apache.spark.sql.types.StructField
import org.apache.spark.sql.types.StructType

object BackupUtils {

  /**
   * Returns the Spark schema for backup data based on the Kudu Schema.
   * Additionally handles adding the RowAction column for incremental backup/restore.
   */
  def dataSchema(schema: Schema, includeRowAction: Boolean = true): StructType = {
    var fields = SparkUtil.sparkSchema(schema).fields
    if (includeRowAction) {
      val changeTypeField = generateRowActionColumn(schema)
      fields = fields ++ Seq(changeTypeField)
    }
    StructType(fields)
  }

  /**
   * Generates a RowAction column and handles column name collisions.
   * The column name can vary because it's accessed positionally.
   */
  private def generateRowActionColumn(schema: Schema): StructField = {
    val columnName = new StringBuffer("backup_row_action")
    // If the column already exists and we need to pick an alternate column name.
    while (schema.hasColumn(columnName.toString)) {
      columnName.append("_")
    }
    StructField(columnName.toString, ByteType)
  }

}