Known Issues in Apache Impala
Learn about the known issues in Impala, the impact or changes to the functionality, and the workaround.
- 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
this:
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
- HADOOP-15720: Queries stuck on failed HDFS calls and not timing out
- In Impala 3.2 and higher, if the following error appears multiple
times in a short duration while running a query, it would mean that the connection between
the
impalad
and the HDFS NameNode is in a bad state.
In Impala 3.1 and lower, the same issue would cause Impala to wait for a long time or not respond without showing the above error message."hdfsOpenFile() for <filename> at backend <hostname:port> failed to finish before the <hdfs_operation_timeout_sec> second timeout "
- IMPALA-532: Impala should tolerate bad locale settings
-
If the
LC_*
environment variables specify an unsupported locale, Impala does not start.
- 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> >'
- IMPALA-635: 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 theUNION
must be"null"
.
- 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.
- 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.
- IMPALA-1652: Incorrect results with basic predicate on CHAR typed column
- When comparing a
CHAR
column value to a string literal, the literal value is not blank-padded and so the comparison might fail when it should match.
- IMPALA-1792: ImpalaODBC: Can not get the value in the SQLGetData(m-x th column) after the SQLBindCol(m th column)
- If the ODBC
SQLGetData
is called on a series of columns, the function calls must follow the same order as the columns. For example, if data is fetched from column 2 then column 1, theSQLGetData
call for column 1 returnsNULL
.
- 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 asNaN
orInf
, 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 SELECT
operation 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.
- 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
LIKE
operator 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 JOIN
clauses involving subqueries.
- IMPALA-3094: Incorrect result due to constant evaluation in query with outer join
- 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.
- 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.
- IMPALA-6671: Metadata operations block read-only operations on unrelated tables
- Metadata operations that change the state of a table, like
COMPUTE STATS
orALTER RECOVER PARTITIONS
, may delay metadata propagation of unrelated unloaded tables triggered by statements likeDESCRIBE
orSELECT
queries.
- IMPALA-7072: Impala does not support Heimdal Kerberos
- 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.
Technical Service Bulletins
- TSB 2021-479: Impala can return incomplete results through JDBC and ODBC clients in all CDP offerings
- In CDP, we introduced a timeout on queries to Impala defaulting to 10 seconds. The timeout setting is called FETCH_ROWS_TIMEOUT_MS. Due to this setting, JDBC, ODBC, and Beeswax clients running Impala queries believe the data returned at 10 seconds is a complete dataset and present it as the final output. However, in cases where there are still results to return after this timeout has passed, when the driver closes the connection, based on the timeout, it results in a scenario where the query results are incomplete.
- Upstream JIRA
- IMPALA-7561
- Knowledge article
- For the latest update on this issue, see the corresponding Knowledge article: TSB-2021 479: Impala can return incomplete results through JDBC and ODBC clients in all CDP offerings
- TSB 2022-543: Impala query with predicate on analytic function may produce incorrect results
- Apache Impala may produce incorrect results for a query which has all of the following
conditions:
- There are two or more analytic functions (for example,
row_number()
) in an inline view - Some of the functions have partition-by expression while the others do not
- There is a predicate on the inline view's output expression corresponding to the analytic function
- There are two or more analytic functions (for example,
- Upstream JIRA
- IMPALA-11030
- Knowledge article
- For the latest update on this issue, see the corresponding Knowledge article: TSB 2022-543: Impala query with predicate on analytic function may produce incorrect results