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https://issues.apache.org/jira/browse/HIVE-6131?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13963728#comment-13963728
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Szehon Ho commented on HIVE-6131:
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Hm I understand file-format may differ between partition and table, that was
the point of HIVE-3833. But just for my understanding, did you find any use
for the partition-columns being different from table-columns (being the
original)?
In my experience, I had seen that LazyBinaryColumnarSerde (and other serde) can
use a schema with more columns to de-serialize data than what the data was
written with. If thats the case, cant we make the column set same for
partition and table, during 'alter table'?
> New columns after table alter result in null values despite data
> ----------------------------------------------------------------
>
> Key: HIVE-6131
> URL: https://issues.apache.org/jira/browse/HIVE-6131
> Project: Hive
> Issue Type: Bug
> Affects Versions: 0.11.0, 0.12.0, 0.13.0
> Reporter: James Vaughan
> Priority: Minor
> Attachments: HIVE-6131.1.patch
>
>
> Hi folks,
> I found and verified a bug on our CDH 4.0.3 install of Hive when adding
> columns to tables with Partitions using 'REPLACE COLUMNS'. I dug through the
> Jira a little bit and didn't see anything for it so hopefully this isn't just
> noise on the radar.
> Basically, when you alter a table with partitions and then reupload data to
> that partition, it doesn't seem to recognize the extra data that actually
> exists in HDFS- as in, returns NULL values on the new column despite having
> the data and recognizing the new column in the metadata.
> Here's some steps to reproduce using a basic table:
> 1. Run this hive command: CREATE TABLE jvaughan_test (col1 string)
> partitioned by (day string);
> 2. Create a simple file on the system with a couple of entries, something
> like "hi" and "hi2" separated by newlines.
> 3. Run this hive command, pointing it at the file: LOAD DATA LOCAL INPATH
> '<FILEDIR>' OVERWRITE INTO TABLE jvaughan_test PARTITION (day = '2014-01-02');
> 4. Confirm the data with: SELECT * FROM jvaughan_test WHERE day =
> '2014-01-02';
> 5. Alter the column definitions: ALTER TABLE jvaughan_test REPLACE COLUMNS
> (col1 string, col2 string);
> 6. Edit your file and add a second column using the default separator
> (ctrl+v, then ctrl+a in Vim) and add two more entries, such as "hi3" on the
> first row and "hi4" on the second
> 7. Run step 3 again
> 8. Check the data again like in step 4
> For me, this is the results that get returned:
> hive> select * from jvaughan_test where day = '2014-01-01';
> OK
> hi NULL 2014-01-02
> hi2 NULL 2014-01-02
> This is despite the fact that there is data in the file stored by the
> partition in HDFS.
> Let me know if you need any other information. The only workaround for me
> currently is to drop partitions for any I'm replacing data in and THEN
> reupload the new data file.
> Thanks,
> -James
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