measure/src/main/scala/org/apache/griffin/measure/datasource/connector/batch/HiveBatchDataConnector.scala

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package org.apache.griffin.measure.datasource.connector.batch

import org.apache.griffin.measure.configuration.dqdefinition.DataConnectorParam
import org.apache.griffin.measure.context.TimeRange
import org.apache.griffin.measure.datasource.TimestampStorage
import org.apache.spark.sql.{DataFrame, SparkSession}
import org.apache.griffin.measure.utils.ParamUtil._

/**
  * batch data connector for hive table
  */
case class HiveBatchDataConnector(@transient sparkSession: SparkSession,
                                  dcParam: DataConnectorParam,
                                  timestampStorage: TimestampStorage
                                 ) extends BatchDataConnector {

  val config = dcParam.getConfig

  val Database = "database"
  val TableName = "table.name"
  val Where = "where"

  val database = config.getString(Database, "default")
  val tableName = config.getString(TableName, "")
  val whereString = config.getString(Where, "")

  val concreteTableName = s"${database}.${tableName}"
  val wheres = whereString.split(",").map(_.trim).filter(_.nonEmpty)

  def data(ms: Long): (Option[DataFrame], TimeRange) = {
    val dfOpt = try {
      val dtSql = dataSql
      info(dtSql)
      val df = sparkSession.sql(dtSql)
      val dfOpt = Some(df)
      val preDfOpt = preProcess(dfOpt, ms)
      preDfOpt
    } catch {
      case e: Throwable => {
        error(s"load hive table ${concreteTableName} fails: ${e.getMessage}")
        None
      }
    }
    val tmsts = readTmst(ms)
    (dfOpt, TimeRange(ms, tmsts))
  }


  private def tableExistsSql(): String = {
//    s"SHOW TABLES LIKE '${concreteTableName}'"    // this is hive sql, but not work for spark sql
    s"tableName LIKE '${tableName}'"
  }

  private def metaDataSql(): String = {
    s"DESCRIBE ${concreteTableName}"
  }

  private def dataSql(): String = {
    val tableClause = s"SELECT * FROM ${concreteTableName}"
    if (wheres.length > 0) {
      val clauses = wheres.map { w =>
        s"${tableClause} WHERE ${w}"
      }
      clauses.mkString(" UNION ALL ")
    } else tableClause
  }

}