Hive小文件处理

MR任务

mr任务参考链接

set hive.exec.reducers.max=3

set hive.exec.dynamic.partition.mode = true; --使用动态分区时，设置为ture。 set hive.exec.dynamic.partition.mode = nonstrict; --动态分区模式，默认值：strict，表示必须指定一个分区为静态分区；nonstrict模式表示允许所有的分区字段都可以使用动态分区。一般需要设置为nonstrict。 set hive.exec.max.dynamic.partitions.pernode =10; --在每个执行MR的节点上，最多可以创建多少个动态分区，默认值：100。 set hive.exec.max.dynamic.partitions =1000; --在所有执行MR的节点上，最多一共可以创建多少个动态分区，默认值：1000。 set hive.exec.max.created.files = 100000; --整个MR Job中最多可以创建多少个HDFS文件，默认值：100000。 set hive.error.on.empty.partition = false; --当有空分区产生时，是否抛出异常，默认值：false。 Hive文件产生大量小文件的原因： 一是文件本身的原因：小文件多，以及文件的大小； 二是使用动态分区，可能会导致产生大量分区，从而产生很多小文件，也会导致产生很多Mapper； 三是Reduce数量较多，Hive SQL输出文件的数量和Reduce的个数是一样的。 小文件带来的影响： 文件的数量和大小决定Mapper任务的数量，小文件越多，Mapper任务越多，每一个Mapper都会启动一个JVM来运行，所以这些任务的初始化和执行会花费大量的资源，严重影响性能。 在NameNode中每个文件大约占150字节，小文件多，会严重影响NameNode性能。 解决小文件问题： 如果动态分区数量不可预测，最好不用。如果用，最好使用distributed by分区字段，这样会对字段进行一个hash操作，把相同的分区给同一个Reduce处理； 减少Reduce数量； 进行以一些参数调整。

Hdfs文件数

指定目录下的文件夹，文件，容量大小
[root@mz-hadoop-01 ~]# hdfs dfs -count  /user/hive/warehouse/paascloud_tcm.db/dwd/dwd_t_record_detailed
         568         7433         6065483664 /user/hive/warehouse/paascloud_tcm.db/dwd/dwd_t_record_detailed
 
[root@mz-hadoop-01 ~]# hdfs dfs -count -h /user/hive/warehouse/paascloud_tcm.db/dwd/dwd_t_record_detailed
         568        7.3 K              5.6 G /user/hive/warehouse/paascloud_tcm.db/dwd/dwd_t_record_detailed
 

Hive文件数

SELECT tbl_id,SUM(PARAM_VALUE) AS file_cnts
FROM
(
SELECT * FROM PARTITIONS WHERE tbl_id='97387'
) a
 LEFT JOIN (SELECT * FROM partition_params WHERE PARAM_KEY='numFiles' ) b
ON a.part_id=b.part_id

GROUP BY tbl_id
ORDER BY file_cnts DESC;

TBL_ID  file_cnts  
------  -----------
 97387         2082

所有文件数

SELECT SUM(PARAM_VALUE) AS file_cnts
FROM
(
SELECT * FROM PARTITIONS
) a
 LEFT JOIN (SELECT * FROM partition_params WHERE PARAM_KEY='numFiles' ) b
ON a.part_id=b.part_id


file_cnts  
-----------
     340323

表文件数topN

SELECT e.*,f.*
FROM 
(

SELECT c.*,d.db_id,d.tbl_name
FROM
(
SELECT tbl_id,SUM(PARAM_VALUE) AS file_cnts
FROM
(
SELECT * FROM PARTITIONS
) a
 LEFT JOIN (
 SELECT * FROM partition_params WHERE PARAM_KEY='numFiles' 
 ) b
ON a.part_id=b.part_id

GROUP BY tbl_id
ORDER BY file_cnts DESC
) c
 LEFT JOIN (
 SELECT * FROM tbls
) d
ON c.tbl_id=d.tbl_id

) e LEFT JOIN
(

SELECT db_id AS db_id2,`desc`,DB_LOCATION_URI,NAME as db_name,OWNER_NAME,OWNER_TYPE FROM dbs
)f ON e.db_id=f.DB_ID2

库文件数topN

select 
db_id,db_name,DB_LOCATION_URI,sum(file_cnts) as file_cnts
from (

SELECT e.*,f.*
FROM 
(

SELECT c.*,d.db_id,d.tbl_name
FROM
(
SELECT tbl_id,SUM(PARAM_VALUE) AS file_cnts
FROM
(
SELECT * FROM PARTITIONS
) a
 LEFT JOIN (
 SELECT * FROM partition_params WHERE PARAM_KEY='numFiles' 
 ) b
ON a.part_id=b.part_id

GROUP BY tbl_id
ORDER BY file_cnts DESC
) c
 LEFT JOIN (
 SELECT * FROM tbls
) d
ON c.tbl_id=d.tbl_id

) e LEFT JOIN
(

SELECT db_id AS db_id2,`desc`,DB_LOCATION_URI,NAME as db_name,OWNER_NAME,OWNER_TYPE FROM dbs
)f ON e.db_id=f.DB_ID2


)g group by db_id,db_name,DB_LOCATION_URI order by file_cnts desc

小文件压缩任务

package com.mingzhi.common.universal

import com.mingzhi.common.interf.{IDate, MySaveMode}
import com.mingzhi.common.utils.{HiveUtil, SinkUtil, SparkUtils, TableUtils}
import org.apache.commons.lang3.StringUtils
import org.apache.spark.sql.{DataFrame, SparkSession}
import org.apache.spark.storage.StorageLevel

/**
 * 处理只有一个分区dt的表
 */
object table_compress_process {

  private var hive_dbs: String = "paascloud"
  private var hive_tables: String = "dwd_order_info_abi"
  private var dt: String = "2023-06-30"
  private var dt1: String = "2023-06-30"

  def main(args: Array[String]): Unit = {


    System.setProperty("HADOOP_USER_NAME", "root")

    val builder = SparkUtils.getBuilder

    if (System.getProperties.getProperty("os.name").contains("Windows")) {

      builder.master("local[*]")
    } else {
      hive_dbs = args(0)
      hive_tables = args(1)
      dt = args(2)
      dt1 = args(3)
    }

    val spark: SparkSession = builder.appName("clean_process").getOrCreate()
    HiveUtil.openDynamicPartition(spark)
    spark.sql("set spark.sql.shuffle.partitions=1")

    if ("all".equalsIgnoreCase(hive_dbs)) {

      val builder = new StringBuilder()


      val frame_db = spark.sql("show databases").select("databaseName")

      frame_db.show(false)

      frame_db.collect().foreach(db => {

        builder.append(db.toString().replace("[", "").replace("]", ","))

      })


      println("dbs:" + builder.toString())

      hive_dbs = builder.toString()

    }

    hive_dbs.split(",").foreach(db => {

      if (StringUtils.isNotBlank(db)) {

        if ("all".equalsIgnoreCase(hive_tables)) {

          compress_all_table(spark, db)

        } else {

          hive_tables.split(",").foreach(t => {

            compress_the_table(spark, db, t)
          })

        }
      }
    })
    spark.stop()

  }

  private def compress_the_table(spark: SparkSession, hive_db: String, table: String): Unit = {

    println("compress_the_table======>:" + hive_db + "." + table)

    spark.sql(s"use $hive_db")
    if (TableUtils.tableExists(spark, hive_db, table)) {

      try {

        new IDate {
          override def onDate(dt: String): Unit = {


            /**
             * 建议：对需要checkpoint的RDD，先执行persist(StorageLevel.DISK_ONLY)
             */
            val f1 = spark.sql(
              s"""
                 |
                 |select * from $hive_db.$table where dt='$dt'
                 |""".stripMargin)
              .persist(StorageLevel.MEMORY_ONLY)

            val r_ck: (DataFrame, String) = SparkUtils.persistDataFrame(spark, f1)


            val f2 = r_ck._1

            println("f2 show===>")
            f2.show(false)
            
            val type_ = TableUtils.getCompressType(spark, hive_db, table)

            if ("HiveFileFormat".equalsIgnoreCase(type_)) {

              println("sink HiveFileFormat table:" + table)

              SinkUtil.sink_to_hive_HiveFileFormat(spark, f2, hive_db, table, null)

            } else {

              //spark表
              SinkUtil.sink_to_hive(dt
                , spark
                , f2
                , hive_db
                , table
                , type_
                , MySaveMode.OverWriteByDt
                , 1)

            }

            spark.sql(s"drop table ${r_ck._2} ")
          }
        }.invoke(dt, dt1)

      } catch {
        case e: org.apache.spark.sql.AnalysisException => {
          println("exception1:" + e)
        }
        case e: Exception => println("exception:" + e)
      }

    }
  }

  private def compress_all_table(spark: SparkSession, hive_db: String): Unit = {

    spark.sql(s"use $hive_db")
    val frame_table = spark.sql(s"show tables")

    frame_table.show(100, false)
    frame_table.printSchema()

    frame_table
      .filter(r => {
        !r.getAs[Boolean]("isTemporary")
      })
      .select("tableName").collect().foreach(r => {
      //r:[ads_order_topn]
      val table = r.toString().replace("[", "").replace("]", "")

      println("compress table:" + hive_db + "." + table)

      if (TableUtils.tableExists(spark, hive_db, table)) {

        try {

          new IDate {
            override def onDate(dt: String): Unit = {


              val f1 = spark.sql(
                s"""
                   |
                   |select * from $hive_db.$table where dt='$dt'
                   |""".stripMargin)

              SinkUtil.sink_to_hive(dt, spark, f1, hive_db, table, "orc", MySaveMode.OverWriteByDt, 1)

            }
          }.invoke(dt, dt1)


        } catch {
          case e: org.apache.spark.sql.AnalysisException => {
            println("exception1:" + e)
          }
          case e: Exception => println("exception:" + e)
        }

      }
    })
  }
}