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https://issues.apache.org/jira/browse/HIVE-21861?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16881595#comment-16881595
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Rajkumar Singh commented on HIVE-21861:
---------------------------------------
As per my understanding, it looks that it is expected to get the lazystring
during assignrow. this is how the code flow looks like.
Kafka Serde delegate to LazySimpleSerDe
https://github.com/apache/hive/blob/eba668eed6fecce6bae87fb77ca056b8e34ad5e2/kafka-handler/src/java/org/apache/hadoop/hive/kafka/KafkaSerDe.java#L102
LazySimpleSerDe initialize and set
https://github.com/apache/hive/blob/8a606abdec0f92d60653d892b2f92ff729f1c020/serde/src/java/org/apache/hadoop/hive/serde2/lazy/LazySimpleSerDe.java#L119
and set the object inspector to
LazySimpleStructObjectInspector<org.apache.hadoop.hive.serde2.lazy.objectinspector.primitive.LazyStringObjectInspector>
now during deserialization, lazy serde deserialize the text writable and return
row as lazystruct
https://github.com/apache/hive/blob/eba668eed6fecce6bae87fb77ca056b8e34ad5e2/kafka-handler/src/java/org/apache/hadoop/hive/kafka/VectorizedKafkaRecordReader.java#L157
https://github.com/apache/hive/blob/eba668eed6fecce6bae87fb77ca056b8e34ad5e2/kafka-handler/src/java/org/apache/hadoop/hive/kafka/KafkaSerDe.java#L206
since delegateDeserializerOI is LazyString object inspector hence the following
piece of code return the lazy string.
https://github.com/apache/hive/blob/eba668eed6fecce6bae87fb77ca056b8e34ad5e2/kafka-handler/src/java/org/apache/hadoop/hive/kafka/KafkaSerDe.java#L210
> ClassCastException during CTAS over external table using KafkaStorageHandler
> ----------------------------------------------------------------------------
>
> Key: HIVE-21861
> URL: https://issues.apache.org/jira/browse/HIVE-21861
> Project: Hive
> Issue Type: Bug
> Components: kafka integration
> Affects Versions: 4.0.0
> Reporter: Justin Leet
> Assignee: Rajkumar Singh
> Priority: Major
> Attachments: HIVE-21861.patch
>
>
> To reproduce, create a table similar to the following:
> {code}
> CREATE EXTERNAL TABLE <table>
> (raw_value STRING)
> ROW FORMAT DELIMITED
> LINES TERMINATED BY '\n'
> STORED BY 'org.apache.hadoop.hive.kafka.KafkaStorageHandler'
> TBLPROPERTIES(
> "kafka.topic"="<kafka_topic>",
> "kafka.bootstrap.servers"="<bootstrap_servers>",
> "kafka.consumer.security.protocol"="PLAINTEXT",
> "kafka.serde.class"="org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe");
> {code}
> Note the SerDe isn't the default SerDe. Additionally, this error occurs when
> vectorization is enabled.
> Basic queries work fine:
> {code}
> SELECT * FROM <table> LIMIT 1;
> {code}
> Doing a CTAS to bring it into a managed table fails:
> {code}
> CREATE TABLE <managed_table> AS
> SELECT * FROM <table>;
> {code}
> The exception is:
> {code}
> Caused by: java.lang.ClassCastException:
> org.apache.hadoop.hive.serde2.lazy.LazyString cannot be cast to
> org.apache.hadoop.io.TextCaused by: java.lang.ClassCastException:
> org.apache.hadoop.hive.serde2.lazy.LazyString cannot be cast to
> org.apache.hadoop.io.Text at
> org.apache.hadoop.hive.ql.exec.vector.VectorAssignRow.assignRowColumn(VectorAssignRow.java:471)
> at
> org.apache.hadoop.hive.ql.exec.vector.VectorAssignRow.assignRowColumn(VectorAssignRow.java:350)
> at
> org.apache.hadoop.hive.kafka.VectorizedKafkaRecordReader.readNextBatch(VectorizedKafkaRecordReader.java:159)
> at
> org.apache.hadoop.hive.kafka.VectorizedKafkaRecordReader.next(VectorizedKafkaRecordReader.java:113)
> at
> org.apache.hadoop.hive.kafka.VectorizedKafkaRecordReader.next(VectorizedKafkaRecordReader.java:47)
> at
> org.apache.hadoop.hive.ql.io.HiveContextAwareRecordReader.doNext(HiveContextAwareRecordReader.java:360)
> ... 24 more
> {code}
> A workaround to this is to disable vectorization via:
> {code}
> set hive.vectorized.execution.enabled = false;
> {code}
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