@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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