Known Issues in Apache Impala
Learn about the known issues in Impala, the impact or changes to the functionality, and the workaround.
- CDPD-42958: After upgrading the CDH 7.1.8 from CDH 6.x, under certain conditions you cannot insert data into a table
- Under the following conditions, after upgrading from CDH 6.x
to CDH 7.1.8 you cannot insert data into a table from Impala:
- On CDH 6.x, you created a database with Impala in a user specified HDFS location.
- Using Hive, you then created a table in the database.
- Workaround: To resolve this issue, use either one of the following workarounds:
- Using the Ranger Web UI, in the policy repository cm_hdfs, grant the user 'impala' write permission on the directory where the table resides.
- Enter the following command to grant write permission to user 'impala' on the HDFS
directory where the table
hdfs dfs -setfacl -m default:user:impala:rwx <HDFS directory>
- Impala known limitation when querying compacted tables
- When the compaction process deletes the files for a table from the underlying HDFS
location, the Impala service does not detect the changes as the compactions does not
allocate new write ids. When the same table is queried from Impala it throws a 'File does
not exist' exception that looks something like
Query Status: Disk I/O error on <node>:22000: Failed to open HDFS file hdfs://nameservice1/warehouse/tablespace/managed/hive/<database>/<table>/xxxxx Error(2): No such file or directory Root cause: RemoteException: File does not exist: /warehouse/tablespace/managed/hive/<database>/<table>/xxxx
- Use the REFRESH/INVALIDATE statements on the affected table to overcome the 'File does not exist' exception.
- CDPD-28431: Intermittent errors could be potentially encountered when Impala UI is accessed from multiple Knox nodes.
- You must use a single Knox node to access Impala UI.
- Impala api calls via knox require configuration if the knox customized kerberos principal name is a default service user name
- To access impala api calls via knox, if the knox customized kerberos principal name is a default service user name, then configure "authorized_proxy_user_config" by clicking Clusters->impala->configuration. Include the knox customized kerberos principal name in the comma separated list of values <knox_custom_kerberos_principal_name>=*" where <knox_custom_kerberos_principal_name> is the value of the Kerberos Principal in the Knox service. Select Clusters>Knox>Configuration and search for Kerberos Principal to display this value.
- CDPD-21828: Multiple permission assignment through grant is not working
- Problem configuring masking on tables using Ranger
- The following Knowledge Base article describes the behavior when we configure masking on tables using Ranger. This configuration works for Hive, but breaks queries in some scenarios for Impala.
- For a workaround, see the following Knowledge Base article: ERROR: "AnalysisException: No matching function with signature: mask(FLOAT)" when Impala jobs fail with the following error with signature: mask(FLOAT)
- IMPALA-532: Impala should tolerate bad locale settings
LC_*environment variables specify an unsupported locale, Impala does not start.
LC_ALL="C"to the environment settings for both the Impala daemon and the Statestore daemon.
- IMPALA-5605: Configuration to prevent crashes caused by thread resource limits
- Impala could encounter a serious error due to resource usage under very high
concurrency. The error message is similar to:
F0629 08:20:02.956413 29088 llvm-codegen.cc:111] LLVM hit fatal error: Unable to allocate section memory! terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::thread_resource_error> >'
- To prevent such errors, configure each host running an
impalad daemon with the following settings:
Add the following lines in /etc/security/limits.conf:
echo 2000000 > /proc/sys/kernel/threads-max echo 2000000 > /proc/sys/kernel/pid_max echo 8000000 > /proc/sys/vm/max_map_count
impala soft nproc 262144 impala hard nproc 262144
- Avro Scanner fails to parse some schemas
The default value in Avro schema must match type of first union type, e.g. if the
default value is
null, then the first type in the
- Swap the order of the fields in the schema specification. For
["null", "string"]instead of
["string", "null"]. Note that the files written with the problematic schema must be rewritten with the new schema because Avro files have embedded schemas.
- IMPALA-691: Process mem limit does not account for the JVM's memory usage
- Some memory allocated by the JVM used internally by Impala is not counted against the memory limit for the impalad daemon.
- To monitor overall memory usage, use the top command, or add the memory figures in the Impala web UI /memz tab to JVM memory usage shown on the /metrics tab.
- IMPALA-9350: Ranger audit logs for applying column masking policies missing
- Impala is not producing these logs.
- IMPALA-1024: Impala BE cannot parse Avro schema that contains a trailing semi-colon
- If an Avro table has a schema definition with a trailing semicolon, Impala encounters an error when the table is queried.
- Remove trailing semicolon from the Avro schema.
- IMPALA-1652: Incorrect results with basic predicate on CHAR typed column
- When comparing a
CHARcolumn value to a string literal, the literal value is not blank-padded and so the comparison might fail when it should match.
- Use the
RPAD()function to blank-pad literals compared with
CHARcolumns to the expected length.
- IMPALA-1821: Casting scenarios with invalid/inconsistent results
- Using a
CAST()function to convert large literal values to smaller types, or to convert special values such as
Inf, produces values not consistent with other database systems. This could lead to unexpected results from queries.
- IMPALA-2005: A failed CTAS does not drop the table if the insert fails
- If a
CREATE TABLE AS SELECToperation successfully creates the target table but an error occurs while querying the source table or copying the data, the new table is left behind rather than being dropped.
- Drop the new table manually after a failed
CREATE TABLE AS SELECT
- IMPALA-2422: % escaping does not work correctly when occurs at the end in a LIKE clause
- If the final character in the RHS argument of a
LIKEoperator is an escaped
\%character, it does not match a
%final character of the LHS argument.
- IMPALA-2603: Crash: impala::Coordinator::ValidateCollectionSlots
- A query could encounter a serious error if includes multiple nested levels of
INNER JOINclauses involving subqueries.
- IMPALA-3094: Incorrect result due to constant evaluation in query with outer join
OUTER JOINquery could omit some expected result rows due to a constant such as
FALSEin another join clause. For example:
explain SELECT 1 FROM alltypestiny a1 INNER JOIN alltypesagg a2 ON a1.smallint_col = a2.year AND false RIGHT JOIN alltypes a3 ON a1.year = a1.bigint_col; +-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-+ | Explain String | +-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-+ | Estimated Per-Host Requirements: Memory=1.00KB VCores=1 | | | | 00:EMPTYSET | +-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-+
- IMPALA-3509: Breakpad minidumps can be very large when the thread count is high
- The size of the breakpad minidump files grows linearly with the number of threads. By default, each thread adds 8 KB to the minidump size. Minidump files could consume significant disk space when the daemons have a high number of threads.
- Add -\-minidump_size_limit_hint_kb=size to set a soft upper limit on the size of each minidump file. If the minidump file would exceed that limit, Impala reduces the amount of information for each thread from 8 KB to 2 KB. (Full thread information is captured for the first 20 threads, then 2 KB per thread after that.) The minidump file can still grow larger than the "hinted" size. For example, if you have 10,000 threads, the minidump file can be more than 20 MB.
- IMPALA-4978: Impala requires FQDN from hostname command on Kerberized clusters
- The method Impala uses to retrieve the host name while constructing the Kerberos
principal is the
gethostname()system call. This function might not always return the fully qualified domain name, depending on the network configuration. If the daemons cannot determine the FQDN, Impala does not start on a Kerberized cluster.
- Test if a host is affected by checking whether the output of the
hostname command includes the FQDN. On hosts where
hostname, only returns the short name, pass the command-line flag
‑‑hostname=fully_qualified_domain_namein the startup options of all Impala-related daemons.
- IMPALA-7072: Impala does not support Heimdal Kerberos
- OPSAPS-46641: A single parameter exists in Cloudera Manager for specifying the Impala Daemon Load Balancer. Because BDR and Hue need to use different ports when connecting to the load balancer, it is not possible to configure the load balancer value so that BDR and Hue will work correctly in the same cluster.
- The workaround is to use the load balancer configuration either without a port specification, or with the Beeswax port: this will configure BDR. To configure Hue use the "Hue Server Advanced Configuration Snippet (Safety Valve) for impalad_flags" to specify the the load balancer address with the HiveServer2 port.
- CDPD-28139: Set spark.hadoop.hive.stats.autogather to false by default
- As an Impala user, if you submit a query against a table containing data ingested using Spark and you are concerned about the quality of the query plan, you must run COMPUTE STATS against such a table in any case after an ETL operation because numRows created by Spark could be incorrect. Also, use other stats computed by COMPUTE STATS, e.g., Number of Distinct Values (NDV) and NULL count for good selectivity estimates.
- For example, when a user ingests data from a file into a partition of an existing table using Spark, if spark.hadoop.hive.stats.autogather is not set to false explicitly, numRows associated with this partition would be 0 even though there is at least one row in the file. To avoid this, the workaround is to set "spark.hadoop.hive.stats.autogather=false" in the "Spark Client Advanced Configuration Snippet (Safety Valve) for spark-conf/spark-defaults.conf" in Spark's CM Configuration section.
Some of the unresolved issues include: