Apache Hive
Code Changes Might Be Required
The following fixed issues might require changes to your HiveQL code or your configuration:

HIVE-16324 - Truncate table should not work when EXTERNAL property of table is set to true (lower case). This fix changes how the EXTERNAL table property is interpreted by Hive. After this fix, if your current deployment sets the EXTERNAL table property to true (lower case), the external table will no longer be truncated. Read the Jira for further details.
HIVE-18879 - Disallow embedded elements in the UDFXPathUtil class. This fix might change how your XML parser works if you use embedded elements with the xpath UDFs. For example, if you use embedded elements with the following UDFs in your queries: xpath, xpath_short, xpath_int, xpath_long, xpath_float, xpath_double, xpath_number, or xpath_string.

Code Changes Should Not Be Required
The following fixes should not require code changes, but they contain improvements that might enhance your deployment:

HIVE-8472 - Add SET LOCATION option to the ALTER DATABASE command
HIVE-10495 - Hive index creation code throws a NullPointerException if index table is null
HIVE-14786 - Option added to Beeline to display binary column data as a string or a byte array (--convertBinaryArrayToString=[true | false])
HIVE-14792 - Optimization added to minimize AvroSerde reads of the remote schema-file
HIVE-15329 - Fix for when a NullPointerException occurs during table creation
HIVE-15543 - Fix to prevent Hive fetching Spark memory/cores to decide parallelism when Spark dynamic allocation is enabled
HIVE-16601 - Display Session Id and Query Name / Id in Spark UI
HIVE-16663 - Added string caching for rows to Beeline
HIVE-16890 - Remove the superfluous wrapper from HiveVarcharWritable
HIVE-18228 - Azure credential properties added to the HiveConf hidden list
HIVE-18788 - Cleans up inputs in JDBC PreparedStatement (HivePreparedStatement) to fix SQL injection vulnerabilities

Code Changes Should Not Be Required
The following fixes should not require code changes, but they contain improvements that might enhance your deployment:

HIVE-14792 - AvroSerde reads the remote schema-file at least once per mapper, per table reference.
HIVE-18788 - Clean up inputs in JDBC PreparedStatement
HIVE-18879 - Disallow embedded element in UDFXPathUtil needs to work if xercesImpl.jar in classpath
HIVE-19041 - Thrift deserialization of Partition objects should intern fields
HIVE-19424 - NPE In MetaDataFormatters
HIVE-19700 - Workaround for JLine issue with UnsupportedTerminal