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https://issues.apache.org/jira/browse/HIVE-23873?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17161746#comment-17161746
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Syed Shameerur Rahman edited comment on HIVE-23873 at 7/22/20, 10:49 AM:
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[~chiran54321] Even though it makes sense to change the column names to lower
case, I am not sure of the side effects it can have.
The core of the problem here is the inconsistency in the value of
hiveColumnList from JbdcSerde and JdbcRecordIterator. we could do something
like
https://github.com/apache/hive/blob/master/jdbc-handler/src/main/java/org/apache/hive/storage/jdbc/JdbcSerDe.java#L103
in
https://github.com/apache/hive/blob/master/jdbc-handler/src/main/java/org/apache/hive/storage/jdbc/dao/JdbcRecordIterator.java#L62
when conf.get(Constants.JDBC_QUERY) == null which i think will solve this
problem
cc: #[~jcamachorodriguez]
was (Author: srahman):
cc: [~jcamachorodriguez]
> Querying Hive JDBCStorageHandler table fails with NPE
> -----------------------------------------------------
>
> Key: HIVE-23873
> URL: https://issues.apache.org/jira/browse/HIVE-23873
> Project: Hive
> Issue Type: Bug
> Components: HiveServer2, JDBC
> Affects Versions: 3.1.0, 3.1.1, 3.1.2
> Reporter: Chiran Ravani
> Assignee: Chiran Ravani
> Priority: Critical
> Attachments: HIVE-23873.01.patch, HIVE-23873.02.patch
>
>
> Scenario is Hive table having same schema as table in Oracle, however when we
> query the table with data it fails with NPE, below is the trace.
> {code}
> Caused by: java.io.IOException: java.lang.NullPointerException
> at
> org.apache.hadoop.hive.ql.exec.FetchOperator.getNextRow(FetchOperator.java:617)
> ~[hive-exec-3.1.0.3.1.5.0-152.jar:3.1.0.3.1.5.0-152]
> at
> org.apache.hadoop.hive.ql.exec.FetchOperator.pushRow(FetchOperator.java:524)
> ~[hive-exec-3.1.0.3.1.5.0-152.jar:3.1.0.3.1.5.0-152]
> at org.apache.hadoop.hive.ql.exec.FetchTask.fetch(FetchTask.java:146)
> ~[hive-exec-3.1.0.3.1.5.0-152.jar:3.1.0.3.1.5.0-152]
> at org.apache.hadoop.hive.ql.Driver.getResults(Driver.java:2739)
> ~[hive-exec-3.1.0.3.1.5.0-152.jar:3.1.0.3.1.5.0-152]
> at
> org.apache.hadoop.hive.ql.reexec.ReExecDriver.getResults(ReExecDriver.java:229)
> ~[hive-exec-3.1.0.3.1.5.0-152.jar:3.1.0.3.1.5.0-152]
> at
> org.apache.hive.service.cli.operation.SQLOperation.getNextRowSet(SQLOperation.java:473)
> ~[hive-service-3.1.0.3.1.5.0-152.jar:3.1.0.3.1.5.0-152]
> ... 34 more
> Caused by: java.lang.NullPointerException
> at
> org.apache.hive.storage.jdbc.JdbcSerDe.deserialize(JdbcSerDe.java:164)
> ~[hive-jdbc-handler-3.1.0.3.1.5.0-152.jar:3.1.0.3.1.5.0-152]
> at
> org.apache.hadoop.hive.ql.exec.FetchOperator.getNextRow(FetchOperator.java:598)
> ~[hive-exec-3.1.0.3.1.5.0-152.jar:3.1.0.3.1.5.0-152]
> at
> org.apache.hadoop.hive.ql.exec.FetchOperator.pushRow(FetchOperator.java:524)
> ~[hive-exec-3.1.0.3.1.5.0-152.jar:3.1.0.3.1.5.0-152]
> at org.apache.hadoop.hive.ql.exec.FetchTask.fetch(FetchTask.java:146)
> ~[hive-exec-3.1.0.3.1.5.0-152.jar:3.1.0.3.1.5.0-152]
> at org.apache.hadoop.hive.ql.Driver.getResults(Driver.java:2739)
> ~[hive-exec-3.1.0.3.1.5.0-152.jar:3.1.0.3.1.5.0-152]
> at
> org.apache.hadoop.hive.ql.reexec.ReExecDriver.getResults(ReExecDriver.java:229)
> ~[hive-exec-3.1.0.3.1.5.0-152.jar:3.1.0.3.1.5.0-152]
> at
> org.apache.hive.service.cli.operation.SQLOperation.getNextRowSet(SQLOperation.java:473)
> ~[hive-service-3.1.0.3.1.5.0-152.jar:3.1.0.3.1.5.0-152]
> ... 34 more
> {code}
> Problem appears when column names in Oracle are in Upper case and since in
> Hive, table and column names are forced to store in lowercase during
> creation. User runs into NPE error while fetching data.
> While deserializing data, input consists of column names in lower case which
> fails to get the value
> https://github.com/apache/hive/blob/rel/release-3.1.2/jdbc-handler/src/main/java/org/apache/hive/storage/jdbc/JdbcSerDe.java#L136
> {code}
> rowVal = ((ObjectWritable)value).get();
> {code}
> Log Snio:
> =============
> {code}
> 2020-07-17T16:49:09,598 INFO [04ed42ec-91d2-4662-aee7-37e840a06036
> HiveServer2-Handler-Pool: Thread-104]: dao.GenericJdbcDatabaseAccessor (:())
> - Query to execute is [select * from TESTHIVEJDBCSTORAGE]
> 2020-07-17T16:49:10,642 INFO [04ed42ec-91d2-4662-aee7-37e840a06036
> HiveServer2-Handler-Pool: Thread-104]: jdbc.JdbcSerDe (:()) - *** ColumnKey =
> ID
> 2020-07-17T16:49:10,642 INFO [04ed42ec-91d2-4662-aee7-37e840a06036
> HiveServer2-Handler-Pool: Thread-104]: jdbc.JdbcSerDe (:()) - *** Blob value
> = {fname=OW[class=class java.lang.String,value=Name1], id=OW[class=class
> java.lang.Integer,value=1]}
> {code}
> Simple Reproducer for this case.
> =============
> 1. Create table in Oracle
> {code}
> create table TESTHIVEJDBCSTORAGE(ID INT, FNAME VARCHAR(20));
> {code}
> 2. Insert dummy data.
> {code}
> Insert into TESTHIVEJDBCSTORAGE values (1, 'Name1');
> {code}
> 3. Create JDBCStorageHandler table in Hive.
> {code}
> CREATE EXTERNAL TABLE default.TESTHIVEJDBCSTORAGE_HIVE_TBL (ID INT, FNAME
> VARCHAR(20))
> STORED BY 'org.apache.hive.storage.jdbc.JdbcStorageHandler'
> TBLPROPERTIES (
> "hive.sql.database.type" = "ORACLE",
> "hive.sql.jdbc.driver" = "oracle.jdbc.OracleDriver",
> "hive.sql.jdbc.url" = "jdbc:oracle:thin:@orachehostname/XE",
> "hive.sql.dbcp.username" = "chiran",
> "hive.sql.dbcp.password" = "supersecurepassword",
> "hive.sql.table" = "TESTHIVEJDBCSTORAGE",
> "hive.sql.dbcp.maxActive" = "1"
> );
> {code}
> 4. Query Hive table, fails with NPE.
> {code}
> > select * from default.TESTHIVEJDBCSTORAGE_HIVE_TBL;
> INFO : Compiling
> command(queryId=hive_20200717164857_cd6f5020-4a69-4a2d-9e63-9db99d0121bc):
> select * from default.TESTHIVEJDBCSTORAGE_HIVE_TBL
> INFO : Semantic Analysis Completed (retrial = false)
> INFO : Returning Hive schema:
> Schema(fieldSchemas:[FieldSchema(name:testhivejdbcstorage_hive_tbl.id,
> type:int, comment:null), FieldSchema(name:testhivejdbcstorage_hive_tbl.fname,
> type:varchar(20), comment:null)], properties:null)
> INFO : Completed compiling
> command(queryId=hive_20200717164857_cd6f5020-4a69-4a2d-9e63-9db99d0121bc);
> Time taken: 9.914 seconds
> INFO : Executing
> command(queryId=hive_20200717164857_cd6f5020-4a69-4a2d-9e63-9db99d0121bc):
> select * from default.TESTHIVEJDBCSTORAGE_HIVE_TBL
> INFO : Completed executing
> command(queryId=hive_20200717164857_cd6f5020-4a69-4a2d-9e63-9db99d0121bc);
> Time taken: 0.019 seconds
> INFO : OK
> Error: java.io.IOException: java.lang.NullPointerException (state=,code=0)
> {code}
> Assuming that there are no repercussions, can we convert the column names to
> lowercase fetched from Database/Query pointing to table in JDBCStorageHandler?
> Attaching the patch for the case.
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