Dynamic Memory Grant Calculation Thresholds in Oracle PGA Allocation Systems

Abstract

Efficient Program Global Area (PGA) memory allocation is essential for maintaining stable query execution
performance in Oracle database environments, particularly under fluctuating concurrency and mixed workload
conditions. Static memory grant thresholds often fail to adapt to real-time load variations, resulting in work
area spills, temporary I/O overhead, and degraded response times. This study introduces a dynamic threshold
adjustment approach that recalibrates PGA memory grants based on runtime workload behavior and memory
pressure signals rather than static configuration or optimizer estimates. Experimental evaluation across
analytical, transactional, and mixed workloads demonstrates that dynamic thresholding reduces spill
frequency, improves latency stability, enhances throughput fairness among sessions, and accelerates recovery
following overload events. The results highlight the role of adaptive memory tuning in sustaining predictable
performance in enterprise systems, especially those driven by interactive, user-variable application layers.