Behavior of Dynamic Memory Grant Thresholds in Oracle PGA Allocation Frameworks

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.