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| Title | Views | Posted |
|---|---|---|
| 831 | 12-02-2025 10:39 AM |
05-11-2026
02:27 AM
@Scarface This error occurs because your Impala daemon has hit its global "Process" reservation limit of 255.00 GB. Two massive queries are monopolising all available memory reservations, preventing new queries from securing even a minimal 430 MB allocation. Root Cause Culprits: Two running queries have locked up 100% of the daemon's reservation capacity: 2e4e69d2f55f0014:fe08e92f00000000 is holding 153.90 GB. 7b478b1891d4039d:8bb6141800000000 is holding 101.08 GB. Total Reserved: 153.90 GB + 101.08 GB = 254.98 GB (effectively the entire 255 GB limit). Impact: Your new query (b44fc02d59517c5b:...) is denied execution because child_reservations from the existing queries equal the reservation_limit. Immediate Fixes Kill Dominant Queries: Terminate one or both of the top two memory-consuming queries to instantly free up reservation pool space. To kill queries, navigate to Cloudera Manager > Impala > Queries. Retry with Lower Limits: Force your failed query to use less memory by setting strict memory operational limits before execution. sql SET MEM_LIMIT = 2gb; SET BUFFER_POOL_LIMIT = 1gb; -- Re-run your query here
Long-Term Solutions" 1. Implement Impala Admission Control Prevent large queries from running concurrently and destroying cluster stability. Configure Resource Pools in Cloudera Manager with explicit memory caps. Set a hard limit on Maximum Running Queries for memory-heavy pools. Enable Queueing so massive queries wait for prior queries to finish instead of crashing the daemon. Refer documentation: Admission Control and Query Queuing 2. Optimize the Heavy Queries Compute Stats: Ensure COMPUTE STATS has run on all tables involved in the queries so the planner allocates memory accurately. Refer documentation: COMPUTE STATS statement Fix Joins: Check the explain plans of the heavy queries; change large BROADCAST joins to HASH JOIN (shuffle) to distribute memory load across multiple nodes. Refer documentation: EXPLAIN statement and Understanding Performance using EXPLAIN Plan
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05-11-2026
01:58 AM
@Abhijith_Nayak @Sofiane-CH Try below steps for Default Resource Pool Selection. 1. In your Cloudera Manager page, navigate to Clusters (Left side blue pane) > Impala Admission Control Configuration. 2. Click "Default Settings". Select "Allow these users and groups to submit to this pool". Add users or groups separated by comma with no extra spaces. For e.g: A,B,C,D,E 3. Now, click "Edit" in your respective resource pools. In tab "Submission Access Control". Select "Allow these users and groups to submit to this pool". Now, again add users or groups separated by comma with no extra spaces. Below is an example for your mentioned pools resource_pool_1 and resource_pool_2: resource_pool_1 --> A,B,C resource_pool_2 --> D,E 4. Once, the above is done, click "Refresh Dynamic Resource Pools" and restart Impala. References: https://docs.cloudera.com/runtime/7.3.1/impala-manage/topics/impala-dynamic-pool-configure.html https://docs.cloudera.com/runtime/7.3.1/impala-manage/topics/impala-dynamic-pool-settings.html
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12-02-2025
10:39 AM
The error ('H000', '[H000] [ (50404) (SQLDriverConnect)') is a generic ODBC error that indicates the pyodbc connection attempt failed during the initial driver connection phase (SQLDriverConnect), specifically when using the configuration defined in your DSN (Data Source Name) or connection string. The H000 SQLSTATE and the driver-specific error code (50404) often point to a fundamental problem with the connection string's format or parameters. Since isql works but pyodbc does not, the issue is likely how the connection details are being passed or interpreted by the Python environment. Possible RCA: 1. Improper DSN Specification in pyodbc (Most Common): The isql tool implicitly knows how to look up the DSN defined in your odbc.ini file. pyodbc requires the connection string to be in a very specific format. If you pass the DSN name directly without the proper prefix, it can fail with this error. 2. Missing or Incorrect Connection Parameters: If you are using a full connection string instead of a DSN, a single missing or misspelled parameter (like HOST, PORT, Driver, or security mechanisms like AuthMech) will cause the driver to reject the connection immediately. 3. ODBC Driver Manager Conflict (Linux/macOS): On Linux/macOS, Impala uses a driver manager like UnixODBC or iODBC. If pyodbc is compiled against a different driver manager than the one isql uses, they might not be reading the same configuration files or environment variables (ODBCINI, LD_LIBRARY_PATH). Resolution Steps: 1. Fix the pyodbc Connection String Format: Ensure you are explicitly telling pyodbc to use a DSN defined in your configuration files. If connecting using a DSN: Use format DSN=<Your_Impala_DSN_Name>. conn = pyodbc.connect('DSN=MyImpalaDSNName') If connecting using a DSN-less connection string: Ensure all critical parameters are present and correctly formatted. conn_str = (
'Driver={Cloudera ODBC Driver for Impala};'
'Host=<Impala_Host>;'
'Port=<Impala_Port>;'
'AuthMech=3;' # Example: 3 for Username/Password
'UID=<username>;'
'PWD=<password>'
)
conn = pyodbc.connect(conn_str) 2. Verify Security and Authentication Parameters: Since isql might be implicitly handling Kerberos or LDAP, ensure these are explicitly defined for pyodbc: If your cluster uses LDAP (User Name and Password), confirm the UID and PWD parameters are correctly placed and the AuthMech parameter is set to the correct value (often 3 or 5 depending on the driver version). If your cluster uses Kerberos, ensure the KrbRealm, KrbFQDN, and KrbServiceName parameters are correctly defined in your DSN or connection string. 3. Check Library Path (Linux/macOS): If you are using UnixODBC, ensure that the directory containing the ODBC driver manager libraries is included in the LD_LIBRARY_PATH environment variable. The Impala driver may need this path to load correctly, which pyodbc sometimes fails to handle automatically, while isql's setup might cover it. export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/path/to/unixodbc/lib
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09-17-2025
05:15 AM
Hello @Malrashed 1. How much delay are you observing for queries to appear in CM > Impala > Queries page when queries are executed from Hue? 2. Do you observe the same delay when running queries on Impala-shell?
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08-07-2024
12:08 AM
At times in a CDH/CDP cluster, users may have multiple HS2 mapped under a load balancer to achieve high availability and user connection load balancing.
However, for scenarios like separating high-priority jobs, dedicated queue/HS2 requirement for a business unit, dedicated resource allocation, etc., users may have a dedicated HS2 in their cluster.
Below are two methods to create and connect to a dedicated Hive HS2 using ZooKeeper details:
Method 1: Connect using HS2 instance hostname/IP.
Add an instance with an HS2 role on it.
Ensure that this HS2 is not part of your load balancer, in case you want to keep it separate for certain jobs. But this is optional.
To connect to this dedicated HS2 use the below beeline command: beeline> !connect jdbc:hive2://<serverName>:10000/default;
Method 2: Connect using Zookeeper instance details.
Go to Hive_on Tez service > Instances. Add a new HS2 instance.
Click on the "Role Groups" option on the top right side of the instance list.
Click on "Create Role Group". Give name as "Dedicated HS2". Role type: "HiveServer2" and Copy From: "HiveServer2 Default Group".
Select "HiveServer2 Default Group" from the left side menu, select the dedicated HS2 host select "Move Selected Instances To Group" and choose "Dedicated HS2" role group.
After this on the instance page, you will see the dedicated HS2 host reflecting under the "Dedicated HS2" role group.
Now, on the instance page click on the "HiveServer2" hyperlink of your dedicated HS2. Click on Configurations.
Under Dedicated HS2 > Configurations > Advanced > HiveServer2 Advanced Configuration Snippet (Safety Valve) for hive-site.xml.
Add the below parameters and save it. Name: hive.server2.zookeeper.namespace
Value: dedicatedhs2
Restart the dedicated HS2 to apply the changes.
Now, to connect to this dedicated HS2 via beeline using Zookeeper details, you need to mention "zooKeeperNamespace=dedicatedhs2" in your beeline string instead of "zooKeeperNamespace=hiveserver2". Syntax example: beeline -u "jdbc:hive2://<Zk1>:2181,<Zk2>:2181,<Zk3>:2181/;serviceDiscoveryMode=zooKeeper;zooKeeperNamespace=dedicatedhs2"
DISCLAIMER: An external user contributed to this article. Cloudera may not verify that the steps may be applicable for all use cases and may be very specific to a particular distribution. Please follow with caution and at your own risk. If needed, raise a support case to get confirmation.
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