Ngone51 commented on a change in pull request #27670: [SPARK-30937][DOC] Group
Hive migration guides into a sub section of Spark3.0
URL: https://github.com/apache/spark/pull/27670#discussion_r383698104
##########
File path: docs/sql-migration-guide.md
##########
@@ -335,6 +335,10 @@ license: |
- Since Spark 3.0, we upgraded the built-in Hive from 1.2 to 2.3. You need
to migrate your custom SerDes to Hive 2.3 or build your own Spark with
`hive-1.2` profile. See HIVE-15167 for more details.
+ - Since Spark 3.0, we upgraded the built-in Hive from 1.2 to 2.3. The string
representation of a decimal can be different between Hive 1.2 and Hive 2.3 when
using `TRANSFORM` syntax in SQL for script transformation, which depends on
hive's behavior. In Hive 1.2, the string representation omits trailing zeroes.
But in Hive 2.3, it is always padded to 18 digits with trailing zeroes if
necessary.
+
+ - Since Spark 3.0, we upgraded the built-in Hive from 1.2 to 2.3. The local
file system has changed from `org.apache.hadoop.fs.LocalFileSystem` to
`org.apache.hadoop.hive.ql.io.ProxyLocalFileSystem` when using Hadoop APIs,
e.g. `new Path("file:/").getFileSystem(conf)`, and `fs.rename(Path src, Path
dst)` will return `true` and overwrite `dst` in Hive 1.2 but return `false` in
Hive 2.3 if `dst` is an existed file. See HIVE-13705 and HDFS-10385 for more
details.
Review comment:
Removed.
----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
For queries about this service, please contact Infrastructure at:
[email protected]
With regards,
Apache Git Services
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
