Github user mallman commented on the issue:
https://github.com/apache/spark/pull/15998
Hi Guys,
Repeating my comment/query for @ericl. I'm hoping someone can provide
affirmation/refutation to my question before I proceed with new unit tests.
I've run some tests to compare behavior between Hive and Spark in handling
gnarly partition column names, and I found some disparities. We've spent a
considerable amount of time wrangling with partition column name handling
recently, and I'm not sure what semantics we've decided on. To ensure the
behavior I'm seeing is what we're expecting, I want to describe a scenario I
ran.
In my test scenario, I created a table named `test` with the stock Hive
2.1.0 distribution. (I simply downloaded it from its download page and
initialized an empty Derby schema store.) The exact DDL I used to create this
table is as follows:
```create table test(a string) partitioned by (`P``Ðr t` int);```
When I do a `describe test` with `hive` it shows the column name as ``p`дr
t``. It appears to lowercase the P and the cyrillic Ð before storing the table
schema it in the metastore. I then run
```alter table test add partition(`P``Ðr t`=0);```
When I run `show partitions test` in `hive` it gives me ``p`дr t=0``.
Additionally, when I list the contents of the `test` table's base directory in
HDFS, the partition directory entry is
```/user/hive/warehouse/test/p`дr t=0```
If I drop the table, create it with `spark-sql` using the same DDL as
before and do a `describe test`, the partition column is given as ``P`Ðr t``.
Spark has preserved the case of the partition column name. If I then do
```alter table test add partition(`P``Ðr t`=0);```
in `spark-sql` and `show partitions test` I get ``P`Ðr t=0``. When I list
the directory contents in HDFS, I get
```/user/hive/warehouse/test/P`Ðr t=0```
The upshot is Hive is lowercasing the partition column name and Spark is
leaving it unaltered. Is this correct?
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