Skip to main content

Read from a hive table and write back to it using spark sql

By Dinesh
In context to Spark 2.2 -

if we read from an hive table and write to same, we get following exception-

scala> dy.write.mode("overwrite").insertInto("incremental.test2")
             org.apache.spark.sql.AnalysisException: Cannot insert overwrite into table that is also being read from.;
org.apache.spark.sql.AnalysisException: Cannot insert overwrite into table that is also being read from.;






 1. This error means that our process is reading from same table and writing to same table.
 2. Normally, this should work as process writes to directory .hiveStaging... 
 3. This error occurs in case of saveAsTable method, as it overwrites entire table instead of individual partitions.
 4. This error should not occur with insertInto method, as it overwrites partitions not the table.
 5. A reason why this happening is because Hive table has following Spark TBLProperties in its definition. This problem will solve for insertInto method if you remove following Spark TBLProperties - 

> 'spark.sql.partitionProvider' 'spark.sql.sources.provider'
> 'spark.sql.sources.schema.numPartCols
> 'spark.sql.sources.schema.numParts' 'spark.sql.sources.schema.part.0'
> 'spark.sql.sources.schema.part.1' 'spark.sql.sources.schema.part.2'
> 'spark.sql.sources.schema.partCol.0'
> 'spark.sql.sources.schema.partCol.1'





Note that - If used with Parquet output format then it may still throw an exception (, even after removing above TBL Properties). It is possible only when our flow tries to read from and write into same table & format is Parquet.

Comments

Post a Comment

Popular posts

Hive Parse JSON with Array Columns and Explode it in to Multiple rows.

By Dinesh
 Say we have a JSON String like below -  { "billingCountry":"US" "orderItems":[       {          "itemId":1,          "product":"D1"       },   {          "itemId":2,          "product":"D2"       }    ] } And, our aim is to get output parsed like below -  itemId product 1 D1 2 D2   First, We can parse JSON as follows to get JSON String get_json_object(value, '$.orderItems.itemId') as itemId get_json_object(value, '$.orderItems.product') as product Second, Above will result String value like "[1,2]". We want to convert it to Array as follows - split(regexp_extract(get_json_object(value, '$.orderItems.itemId'),'^\\["(.*)\\"]$',1),'","') as itemId split(regexp_extract(get_json_object(value, '$.orderItems.product'),'^\\["(.*)\\"]$',1),&
Post a Comment
Read more




Caused by: java.lang.UnsupportedOperationException: org.apache.parquet.column.values.dictionary.PlainValuesDictionary$PlainIntegerDictionary

By Dinesh
Exception -  Caused by: java.lang.UnsupportedOperationException: org.apache.parquet.column.values.dictionary.PlainValuesDictionary$PlainIntegerDictionary at org.apache.parquet.column.Dictionary.decodeToBinary(Dictionary.java:44) at org.apache.spark.sql.execution.vectorized.ColumnVector.getUTF8String(ColumnVector.java:645) at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIterator.processNext(Unknown Source) Analysis - This might occur because of data type mismatch between Hive Table & written Parquet file. Solution - Correct the data type to match between Hive Table & Parquet
Post a Comment
Read more




org.apache.spark.sql.AnalysisException: Cannot overwrite a path that is also being read from.;

By Dinesh
  Caused by: org.apache.spark.sql.AnalysisException: Cannot overwrite a path that is also being read from.; at org.apache.spark.sql.execution.command.DDLUtils$.verifyNotReadPath(ddl.scala:906) at org.apache.spark.sql.execution.datasources.DataSourceAnalysis$$anonfun$apply$1.applyOrElse(DataSourceStrategy.scala:192) at org.apache.spark.sql.execution.datasources.DataSourceAnalysis$$anonfun$apply$1.applyOrElse(DataSourceStrategy.scala:134) at org.apache.spark.sql.catalyst.trees.TreeNode$$anonfun$2.apply(TreeNode.scala:267) at org.apache.spark.sql.catalyst.trees.TreeNode$$anonfun$2.apply(TreeNode.scala:267) at org.apache.spark.sql.catalyst.trees.CurrentOrigin$.withOrigin(TreeNode.scala:70) at org.apache.spark.sql.catalyst.trees.TreeNode.transformDown(TreeNode.scala:266) at org.apache.spark.sql.catalyst.trees.TreeNode.transform(TreeNode.scala:256) at org.apache.spark.sql.execution.datasources.DataSourceAnalysis.apply(DataSourceStrategy.scala:134) at org.apache.spark.sql.execution.datasource
Post a Comment
Read more




Hadoop Distcp Error Duplicate files in input path

By Dinesh
  One may face following error while copying data from one cluster to other, using Distcp  Command: hadoop distcp -i {src} {tgt} Error: org.apache.hadoop.toolsCopyListing$DulicateFileException: File would cause duplicates. Ideally there can't be same file names. So, what might be happening in your case is you trying to copy partitioned table from one cluster to other. And, 2 different named partitions have same file name. Your solution is to correct Source path  {src}  in your command, such that you provide path uptil partitioned sub directory, not the file. For ex - Refer below : /a/partcol=1/file1.txt /a/partcol=2/file1.txt If you use  {src}  as  "/a/*/*"  then you will get the error  "File would cause duplicates." But, if you use  {src}  as  "/a"  then you will not get error in copying.
Post a Comment
Read more