【问题标题】:Querying Cassandra data using Spark SQL in Scala在 Scala 中使用 Spark SQL 查询 Cassandra 数据
【发布时间】:2018-01-01 07:12:01
【问题描述】:

我正在尝试在 Scala 中使用 Spark SQL 查询 Cassandra 数据。

    import com.datastax.spark.connector._  
    import org.apache.spark.SparkContext 
    import org.apache.spark.SparkContext._
    import org.apache.spark.SparkConf

    val conf= new SparkConf(true)
    .set("spark.cassandra.connection.host","**.*.**.***")
    .set("spark.cassandra.auth.username","****")
    .set("spark.cassandra.auth.password","****")   
    val sc = new SparkContext(conf)

    import org.apache.spark.sql._
    val sqlContext = new SQLContext(sc)
    sqlContext.sql("SELECT * FROM energydata.demodata")  

它会抛出错误:

org.apache.spark.sql.AnalysisException:找不到表或视图: energydata.d emodata;第 1 行,第 14 行; '项目 [*] +- 'UnresolvedRelation energydata.demodata

在 org.apache.spark.sql.catalyst.analysis.package$AnalysisErrorAt.failAnalysis (package.scala:42) 在 org.apache.spark.sql.catalyst.analysis.CheckAnalysis$$anonfun$checkAnalysis $1.apply(CheckAnalysis.scala:82) 在 org.apache.spark.sql.catalyst.analysis.CheckAnalysis$$anonfun$checkAnalysis $1.apply(CheckAnalysis.scala:78) 在 org.apache.spark.sql.catalyst.trees.TreeNode.foreachUp(TreeNode.scala:127) 在 org.apache.spark.sql.catalyst.trees.TreeNode$$anonfun$foreachUp$1.apply(Tre eNode.scala:126) 在 org.apache.spark.sql.catalyst.trees.TreeNode$$anonfun$foreachUp$1.apply(Tre eNode.scala:126) 在 scala.collection.immutable.List.foreach(List.scala:381) 在 org.apache.spark.sql.catalyst.trees.TreeNode.foreachUp(TreeNode.scala:126) 在 org.apache.spark.sql.catalyst.analysis.CheckAnalysis$class.checkAnalysis(Ch eckAnalysis.scala:78) 在 org.apache.spark.sql.catalyst.analysis.Analyzer.checkAnalysis(Analyzer.scal 答:91)在 org.apache.spark.sql.execution.QueryExecution.assertAnalyzed(QueryExecution .scala:52) 在 org.apache.spark.sql.Dataset$.ofRows(Dataset.scala:66) 在 org.apache.spark.sql.SparkSession.sql(SparkSession.scala:623) 在 org.apache.spark.sql.SQLContext.sql(SQLContext.scala:691) ... 54 省略了

我只想在不干扰 cassandra 表的情况下读取表数据。我尝试了给定here 的解决方案,将hive-site.xml 文件添加到spark/conf。但是当我将它添加到spark/conf 时,火花似乎无法正常工作。

at org.apache.spark.sql.SparkSession$Builder$$anonfun$getOrCreate$5.appl
y(SparkSession.scala:938)
        at org.apache.spark.sql.SparkSession$Builder$$anonfun$getOrCreate$5.appl
y(SparkSession.scala:938)
        at scala.collection.mutable.HashMap$$anonfun$foreach$1.apply(HashMap.sca
la:99)
        at scala.collection.mutable.HashMap$$anonfun$foreach$1.apply(HashMap.sca
la:99)
        at scala.collection.mutable.HashTable$class.foreachEntry(HashTable.scala
:230)
        at scala.collection.mutable.HashMap.foreachEntry(HashMap.scala:40)
        at scala.collection.mutable.HashMap.foreach(HashMap.scala:99)
        at org.apache.spark.sql.SparkSession$Builder.getOrCreate(SparkSession.sc
ala:938)
        at org.apache.spark.repl.Main$.createSparkSession(Main.scala:97)
        at $line3.$read$$iw$$iw.<init>(<console>:15)
        at $line3.$read$$iw.<init>(<console>:42)
        at $line3.$read.<init>(<console>:44)
        at $line3.$read$.<init>(<console>:48)
        at $line3.$read$.<clinit>(<console>)
        at $line3.$eval$.$print$lzycompute(<console>:7)
        at $line3.$eval$.$print(<console>:6)
        at $line3.$eval.$print(<console>)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
        at java.lang.reflect.Method.invoke(Unknown Source)
        at scala.tools.nsc.interpreter.IMain$ReadEvalPrint.call(IMain.scala:786)

        at scala.tools.nsc.interpreter.IMain$Request.loadAndRun(IMain.scala:1047
)
        at scala.tools.nsc.interpreter.IMain$WrappedRequest$$anonfun$loadAndRunR
eq$1.apply(IMain.scala:638)
        at scala.tools.nsc.interpreter.IMain$WrappedRequest$$anonfun$loadAndRunR
eq$1.apply(IMain.scala:637)
        at scala.reflect.internal.util.ScalaClassLoader$class.asContext(ScalaCla
ssLoader.scala:31)
        at scala.reflect.internal.util.AbstractFileClassLoader.asContext(Abstrac
tFileClassLoader.scala:19)
        at scala.tools.nsc.interpreter.IMain$WrappedRequest.loadAndRunReq(IMain.
scala:637)
        at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:569)
        at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:565)
        at scala.tools.nsc.interpreter.ILoop.interpretStartingWith(ILoop.scala:8
07)
        at scala.tools.nsc.interpreter.ILoop.command(ILoop.scala:681)
        at scala.tools.nsc.interpreter.ILoop.processLine(ILoop.scala:395)
        at org.apache.spark.repl.SparkILoop$$anonfun$initializeSpark$1.apply$mcV
$sp(SparkILoop.scala:38)
        at org.apache.spark.repl.SparkILoop$$anonfun$initializeSpark$1.apply(Spa
rkILoop.scala:37)
        at org.apache.spark.repl.SparkILoop$$anonfun$initializeSpark$1.apply(Spa
rkILoop.scala:37)
        at scala.tools.nsc.interpreter.IMain.beQuietDuring(IMain.scala:214)
        at org.apache.spark.repl.SparkILoop.initializeSpark(SparkILoop.scala:37)

        at org.apache.spark.repl.SparkILoop.loadFiles(SparkILoop.scala:98)
        at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply$mcZ$sp(ILo
op.scala:920)
        at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply(ILoop.scal
a:909)
        at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply(ILoop.scal
a:909)
        at scala.reflect.internal.util.ScalaClassLoader$.savingContextLoader(Sca
laClassLoader.scala:97)
        at scala.tools.nsc.interpreter.ILoop.process(ILoop.scala:909)
        at org.apache.spark.repl.Main$.doMain(Main.scala:70)
        at org.apache.spark.repl.Main$.main(Main.scala:53)
        at org.apache.spark.repl.Main.main(Main.scala)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
        at java.lang.reflect.Method.invoke(Unknown Source)
        at org.apache.spark.deploy.SparkSubmit$.org$apache$spark$deploy$SparkSub
mit$$runMain(SparkSubmit.scala:755)
        at org.apache.spark.deploy.SparkSubmit$.doRunMain$1(SparkSubmit.scala:18
0)
        at org.apache.spark.deploy.SparkSubmit$.submit(SparkSubmit.scala:205)
        at org.apache.spark.deploy.SparkSubmit$.main(SparkSubmit.scala:119)
        at org.apache.spark.deploy.SparkSubmit.main(SparkSubmit.scala)
Caused by: java.lang.RuntimeException: Unable to instantiate org.apache.hadoop.h
ive.ql.metadata.SessionHiveMetaStoreClient
        at org.apache.hadoop.hive.metastore.MetaStoreUtils.newInstance(MetaStore
Utils.java:1523)
        at org.apache.hadoop.hive.metastore.RetryingMetaStoreClient.<init>(Retry
ingMetaStoreClient.java:86)
        at org.apache.hadoop.hive.metastore.RetryingMetaStoreClient.getProxy(Ret
ryingMetaStoreClient.java:132)
        at org.apache.hadoop.hive.metastore.RetryingMetaStoreClient.getProxy(Ret
ryingMetaStoreClient.java:104)
        at org.apache.hadoop.hive.ql.metadata.Hive.createMetaStoreClient(Hive.ja
va:3005)
        at org.apache.hadoop.hive.ql.metadata.Hive.getMSC(Hive.java:3024)
        at org.apache.hadoop.hive.ql.metadata.Hive.getAllDatabases(Hive.java:123
4)
        ... 87 more
Caused by: java.lang.reflect.InvocationTargetException
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

        at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)

        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Sou
rce)
        at java.lang.reflect.Constructor.newInstance(Unknown Source)
        at org.apache.hadoop.hive.metastore.MetaStoreUtils.newInstance(MetaStore
Utils.java:1521)
        ... 93 more
Caused by: java.lang.IllegalArgumentException: java.net.URISyntaxException: Rela
tive path in absolute URI: file:$%7Btest.warehouse.dir%7D
        at org.apache.hadoop.fs.Path.initialize(Path.java:205)
        at org.apache.hadoop.fs.Path.<init>(Path.java:196)
        at org.apache.hadoop.hive.metastore.Warehouse.getDnsPath(Warehouse.java:
141)
        at org.apache.hadoop.hive.metastore.Warehouse.getDnsPath(Warehouse.java:
146)
        at org.apache.hadoop.hive.metastore.Warehouse.getWhRoot(Warehouse.java:1
59)
        at org.apache.hadoop.hive.metastore.Warehouse.getDefaultDatabasePath(War
ehouse.java:177)
        at org.apache.hadoop.hive.metastore.HiveMetaStore$HMSHandler.createDefau
ltDB_core(HiveMetaStore.java:600)
        at org.apache.hadoop.hive.metastore.HiveMetaStore$HMSHandler.createDefau
ltDB(HiveMetaStore.java:620)
        at org.apache.hadoop.hive.metastore.HiveMetaStore$HMSHandler.init(HiveMe
taStore.java:461)
        at org.apache.hadoop.hive.metastore.RetryingHMSHandler.<init>(RetryingHM
SHandler.java:66)
        at org.apache.hadoop.hive.metastore.RetryingHMSHandler.getProxy(Retrying
HMSHandler.java:72)
        at org.apache.hadoop.hive.metastore.HiveMetaStore.newRetryingHMSHandler(
HiveMetaStore.java:5762)
        at org.apache.hadoop.hive.metastore.HiveMetaStoreClient.<init>(HiveMetaS
toreClient.java:199)
        at org.apache.hadoop.hive.ql.metadata.SessionHiveMetaStoreClient.<init>(
SessionHiveMetaStoreClient.java:74)
        ... 98 more
Caused by: java.net.URISyntaxException: Relative path in absolute URI: file:$%7B
test.warehouse.dir%7D
        at java.net.URI.checkPath(Unknown Source)
        at java.net.URI.<init>(Unknown Source)
        at org.apache.hadoop.fs.Path.initialize(Path.java:202)
        ... 111 more
17/07/26 11:40:06 WARN ObjectStore: Failed to get database default, returning No
SuchObjectException
java.lang.IllegalArgumentException: Error while instantiating 'org.apache.spark.
sql.hive.HiveSessionStateBuilder':
  at org.apache.spark.sql.SparkSession$.org$apache$spark$sql$SparkSession$$insta
ntiateSessionState(SparkSession.scala:1053)
  at org.apache.spark.sql.SparkSession$$anonfun$sessionState$2.apply(SparkSessio
n.scala:130)
  at org.apache.spark.sql.SparkSession$$anonfun$sessionState$2.apply(SparkSessio
n.scala:130)
  at scala.Option.getOrElse(Option.scala:121)
  at org.apache.spark.sql.SparkSession.sessionState$lzycompute(SparkSession.scal
a:129)
  at org.apache.spark.sql.SparkSession.sessionState(SparkSession.scala:126)
  at org.apache.spark.sql.SparkSession$Builder$$anonfun$getOrCreate$5.apply(Spar
kSession.scala:938)
  at org.apache.spark.sql.SparkSession$Builder$$anonfun$getOrCreate$5.apply(Spar
kSession.scala:938)
  at scala.collection.mutable.HashMap$$anonfun$foreach$1.apply(HashMap.scala:99)

  at scala.collection.mutable.HashMap$$anonfun$foreach$1.apply(HashMap.scala:99)

  at scala.collection.mutable.HashTable$class.foreachEntry(HashTable.scala:230)
  at scala.collection.mutable.HashMap.foreachEntry(HashMap.scala:40)
  at scala.collection.mutable.HashMap.foreach(HashMap.scala:99)
  at org.apache.spark.sql.SparkSession$Builder.getOrCreate(SparkSession.scala:93
8)
  at org.apache.spark.repl.Main$.createSparkSession(Main.scala:97)
  ... 47 elided
Caused by: org.apache.spark.sql.AnalysisException: java.lang.RuntimeException: j
ava.lang.RuntimeException: Unable to instantiate org.apache.hadoop.hive.ql.metad
ata.SessionHiveMetaStoreClient;
  at org.apache.spark.sql.hive.HiveExternalCatalog.withClient(HiveExternalCatalo
g.scala:106)
  at org.apache.spark.sql.hive.HiveExternalCatalog.databaseExists(HiveExternalCa
talog.scala:193)
  at org.apache.spark.sql.internal.SharedState.externalCatalog$lzycompute(Shared
State.scala:105)
  at org.apache.spark.sql.internal.SharedState.externalCatalog(SharedState.scala
:93)
  at org.apache.spark.sql.hive.HiveSessionStateBuilder.externalCatalog(HiveSessi
onStateBuilder.scala:39)
  at org.apache.spark.sql.hive.HiveSessionStateBuilder.catalog$lzycompute(HiveSe
ssionStateBuilder.scala:54)
  at org.apache.spark.sql.hive.HiveSessionStateBuilder.catalog(HiveSessionStateB
uilder.scala:52)
  at org.apache.spark.sql.hive.HiveSessionStateBuilder.catalog(HiveSessionStateB
uilder.scala:35)
  at org.apache.spark.sql.internal.BaseSessionStateBuilder.build(BaseSessionStat
eBuilder.scala:289)
  at org.apache.spark.sql.SparkSession$.org$apache$spark$sql$SparkSession$$insta
ntiateSessionState(SparkSession.scala:1050)
  ... 61 more
Caused by: java.lang.RuntimeException: java.lang.RuntimeException: Unable to ins
tantiate org.apache.hadoop.hive.ql.metadata.SessionHiveMetaStoreClient
  at org.apache.hadoop.hive.ql.session.SessionState.start(SessionState.java:522)

  at org.apache.spark.sql.hive.client.HiveClientImpl.<init>(HiveClientImpl.scala
:191)
  at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
  at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
  at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
  at java.lang.reflect.Constructor.newInstance(Unknown Source)
  at org.apache.spark.sql.hive.client.IsolatedClientLoader.createClient(Isolated
ClientLoader.scala:264)
  at org.apache.spark.sql.hive.HiveUtils$.newClientForMetadata(HiveUtils.scala:3
62)
  at org.apache.spark.sql.hive.HiveUtils$.newClientForMetadata(HiveUtils.scala:2
66)
  at org.apache.spark.sql.hive.HiveExternalCatalog.client$lzycompute(HiveExterna
lCatalog.scala:66)
  at org.apache.spark.sql.hive.HiveExternalCatalog.client(HiveExternalCatalog.sc
ala:65)
  at org.apache.spark.sql.hive.HiveExternalCatalog$$anonfun$databaseExists$1.app
ly$mcZ$sp(HiveExternalCatalog.scala:194)
  at org.apache.spark.sql.hive.HiveExternalCatalog$$anonfun$databaseExists$1.app
ly(HiveExternalCatalog.scala:194)
  at org.apache.spark.sql.hive.HiveExternalCatalog$$anonfun$databaseExists$1.app
ly(HiveExternalCatalog.scala:194)
  at org.apache.spark.sql.hive.HiveExternalCatalog.withClient(HiveExternalCatalo
g.scala:97)
  ... 70 more
Caused by: java.lang.RuntimeException: Unable to instantiate org.apache.hadoop.h
ive.ql.metadata.SessionHiveMetaStoreClient
  at org.apache.hadoop.hive.metastore.MetaStoreUtils.newInstance(MetaStoreUtils.
java:1523)
  at org.apache.hadoop.hive.metastore.RetryingMetaStoreClient.<init>(RetryingMet
aStoreClient.java:86)
  at org.apache.hadoop.hive.metastore.RetryingMetaStoreClient.getProxy(RetryingM
etaStoreClient.java:132)
  at org.apache.hadoop.hive.metastore.RetryingMetaStoreClient.getProxy(RetryingM
etaStoreClient.java:104)
  at org.apache.hadoop.hive.ql.metadata.Hive.createMetaStoreClient(Hive.java:300
5)
  at org.apache.hadoop.hive.ql.metadata.Hive.getMSC(Hive.java:3024)
  at org.apache.hadoop.hive.ql.session.SessionState.start(SessionState.java:503)

  ... 84 more
Caused by: java.lang.reflect.InvocationTargetException: java.lang.IllegalArgumen
tException: java.net.URISyntaxException: Relative path in absolute URI: file:$%7
Btest.warehouse.dir%7D
  at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
  at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
  at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
  at java.lang.reflect.Constructor.newInstance(Unknown Source)
  at org.apache.hadoop.hive.metastore.MetaStoreUtils.newInstance(MetaStoreUtils.
java:1521)
  ... 90 more
Caused by: java.lang.IllegalArgumentException: java.net.URISyntaxException: Rela
tive path in absolute URI: file:$%7Btest.warehouse.dir%7D
  at org.apache.hadoop.fs.Path.initialize(Path.java:205)
  at org.apache.hadoop.fs.Path.<init>(Path.java:196)
  at org.apache.hadoop.hive.metastore.Warehouse.getDnsPath(Warehouse.java:141)
  at org.apache.hadoop.hive.metastore.Warehouse.getDnsPath(Warehouse.java:146)
  at org.apache.hadoop.hive.metastore.Warehouse.getWhRoot(Warehouse.java:159)
  at org.apache.hadoop.hive.metastore.Warehouse.getDefaultDatabasePath(Warehouse
.java:177)
  at org.apache.hadoop.hive.metastore.HiveMetaStore$HMSHandler.createDefaultDB_c
ore(HiveMetaStore.java:600)
  at org.apache.hadoop.hive.metastore.HiveMetaStore$HMSHandler.createDefaultDB(H
iveMetaStore.java:620)
  at org.apache.hadoop.hive.metastore.HiveMetaStore$HMSHandler.init(HiveMetaStor
e.java:461)
  at org.apache.hadoop.hive.metastore.RetryingHMSHandler.<init>(RetryingHMSHandl
er.java:66)
  at org.apache.hadoop.hive.metastore.RetryingHMSHandler.getProxy(RetryingHMSHan
dler.java:72)
  at org.apache.hadoop.hive.metastore.HiveMetaStore.newRetryingHMSHandler(HiveMe
taStore.java:5762)
  at org.apache.hadoop.hive.metastore.HiveMetaStoreClient.<init>(HiveMetaStoreCl
ient.java:199)
  at org.apache.hadoop.hive.ql.metadata.SessionHiveMetaStoreClient.<init>(Sessio
nHiveMetaStoreClient.java:74)
  ... 95 more
Caused by: java.net.URISyntaxException: Relative path in absolute URI: file:$%7B
test.warehouse.dir%7D
  at java.net.URI.checkPath(Unknown Source)
  at java.net.URI.<init>(Unknown Source)
  at org.apache.hadoop.fs.Path.initialize(Path.java:202)
  ... 108 more
<console>:14: error: not found: value spark
       import spark.implicits._
              ^
<console>:14: error: not found: value spark
       import spark.sql
              ^
Welcome to
      ____              __
     / __/__  ___ _____/ /__
    _\ \/ _ \/ _ `/ __/  '_/
   /___/ .__/\_,_/_/ /_/\_\   version 2.2.0
      /_/

Using Scala version 2.11.8 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_141)
Type in expressions to have them evaluated.
Type :help for more information.

scala>

我正在使用 scala 2.12.2、Java 1.8.0、cassandra 3.1.1 版本。有没有其他方法可以在 scala 中编写 SQL 查询?

谢谢。

【问题讨论】:

    标签: scala apache-spark sbt apache-spark-sql cassandra-3.0


    【解决方案1】:

    从导入中我了解到您正在使用spark-cassandra-connector。在version compatibility 部分中,他们提到连接器支持 Scala 2.10、2.11 和 Cassandra 2.1.5*、2.2、3.0 和 Spark 2.0、2.1 以及最新版本的连接器。

    所以我建议你降级 scala 和 cassandra 版本并检查它是否有效。

    接下来,我建议您更改尝试访问表的方式。 Datastax 为您提供了一个不同的 API 来连接到 Cassandra。您可以找到相关文档here。

    你可以用 Spark 2.x 做这样的事情,

    val spark = SparkSession.builder()
    .appName("CassTest")
    .master("local[2]")
    .config("spark.cassandra.connection.host","**.*.**.***")
    .config("spark.cassandra.auth.username","****")
    .config("spark.cassandra.auth.password","****") 
    .getOrCreate()
    
    import spark.implicits._
    
    val df = spark
      .read
      .format("org.apache.spark.sql.cassandra")
      .options(Map( "table" -> "words", "keyspace" -> "test" ))
      .load()
    

    最后你可以做df.show
    注意:您尝试的 hive-site.xml 修复是将 Hive 与一些全局可访问的元存储连接,该元存储本身是一个不同的数据存储。所以,这对 Cassandra 不起作用。

    如果这有帮助,请告诉我。干杯。

    【讨论】:

    • 您好,非常感谢您的评论。但我不应该贬低 cassandra 版本。我尝试了上面的代码,当我给 spark.implicites._ &lt;console&gt;:36: error: value implicits is not a member of org.apache.spark.sql.SparkSession.Builder 和 val df = spark.sql("SELECT * FROM energydata.demodata") &lt;console&gt;:36: error: value sql is not a member of org.apache.spark.sql.SparkSess ion.Builder
    • spark 这是您在上面创建的org.apache.spark.sql.SparkSession 的一个实例。您能否确保在此实例上导入 implicits。这适用于 Spark 2.x。您也可以省略隐含行并按照其他方式使用数据框 API 引用我在上面的编辑中提到的表。
    • 它显示相同的错误:&lt;console&gt;:39: error: value read is not a member of org.apache.spark.sql.SparkSession.Builder 。我不知道为什么它显示这个。
    • 你可以发布你的 pom.xml 或 build.sbt(如果是 sbt)
    • 对不起,我不知道从哪里可以得到这个 buld.sbt。我对火花完全陌生。但我在这里使用的 sbt 版本是 sbt 0.13.15
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