[jira] [Commented] (HIVE-4409) Prevent incompatible column type changes

["Lefty Leverenz (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-4409?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14986762#comment-14986762 ] 

Lefty Leverenz commented on HIVE-4409:
--------------------------------------

Doc note:  This added *hive.metastore.disallow.incompatible.col.type.changes* to HiveConf.java, so it needs to be documented in the wiki.

* [Configuration Properties -- MetaStore | https://cwiki.apache.org/confluence/display/Hive/Configuration+Properties#ConfigurationProperties-MetaStore]

HIVE-12320 changes the default value to true.

> Prevent incompatible column type changes
> ----------------------------------------
>
>                 Key: HIVE-4409
>                 URL: https://issues.apache.org/jira/browse/HIVE-4409
>             Project: Hive
>          Issue Type: Improvement
>          Components: CLI, Metastore
>    Affects Versions: 0.10.0
>            Reporter: Dilip Joseph
>            Assignee: Dilip Joseph
>            Priority: Minor
>              Labels: TODOC12
>             Fix For: 0.12.0
>
>         Attachments: HIVE-4409.D10539.1.patch, HIVE-4409.D10539.2.patch, hive.4409.1.patch
>
>
> If a user changes the type of an existing column of a partitioned table to an incompatible type, subsequent accesses of old partitions will result in a ClassCastException (see example below).  We should prevent the user from making incompatible type changes.  This feature will be controlled by a new config parameter.
> Example:
> CREATE TABLE test_table123 (a INT, b MAP<STRING, STRING>) PARTITIONED BY (ds STRING) STORED AS SEQUENCEFILE;
> INSERT OVERWRITE TABLE test_table123 PARTITION(ds="foo1") SELECT 1, MAP("a1", "b1") FROM src LIMIT 1;
> SELECT * from test_table123 WHERE ds="foo1";
> ALTER TABLE test_table123 REPLACE COLUMNS (a INT, b STRING);
> SELECT * from test_table123 WHERE ds="foo1";
> The last SELECT fails with the following exception:
> Failed with exception java.io.IOException:java.lang.ClassCastException: org.apache.hadoop.hive.serde2.lazy.objectinspector.LazyMapObjectInspector cannot be cast to org.apache.hadoop.hive.serde2.objectinspector.PrimitiveObjectInspector
> java.io.IOException: java.lang.ClassCastException: org.apache.hadoop.hive.serde2.lazy.objectinspector.LazyMapObjectInspector cannot be cast to org.apache.hadoop.hive.serde2.objectinspector.PrimitiveObjectInspector
>   at org.apache.hadoop.hive.ql.exec.FetchOperator.getNextRow(FetchOperator.java:544)
>   at org.apache.hadoop.hive.ql.exec.FetchOperator.pushRow(FetchOperator.java:488)
>   at org.apache.hadoop.hive.ql.exec.FetchTask.fetch(FetchTask.java:136)
>   at org.apache.hadoop.hive.ql.Driver.getResults(Driver.java:1406)
>   at org.apache.hadoop.hive.cli.CliDriver.processLocalCmd(CliDriver.java:271)
>   at org.apache.hadoop.hive.cli.CliDriver.processCmd(CliDriver.java:216)
>   at org.apache.hadoop.hive.cli.CliDriver.processLine(CliDriver.java:413)
>   at org.apache.hadoop.hive.cli.CliDriver.processLine(CliDriver.java:348)
>   at org.apache.hadoop.hive.ql.QTestUtil.executeClient(QTestUtil.java:790)
>   at org.apache.hadoop.hive.cli.TestCliDriver.runTest(TestCliDriver.java:124)
>   at org.apache.hadoop.hive.cli.TestCliDriver.testCliDriver_class_cast(TestCliDriver.java:108)
> The ALTER TABLE statement is blocked if you set the following parameter, introduced int the fix to this JIRA:
> SET hive.metastore.disallow.incompatible.col.type.changes=true;



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