Query optimization is a crucial problem in database systems that has been studied for decades. Learned query optimizers (LQOs) can improve performance over time by incorporating feedback; however, they suffer from cold-start issues and often require retraining when workloads shift or schemas change. Recent LLM-based query optimizers leverage pre-trained and fine-tuned LLMs to mitigate these challenges. Nevertheless, they neglect LLMs' in-context learning and execution records as feedback for continuous evolution. In this paper, we present SEFRQO, a S elf- E volving F ine-tuned R AG-based Q uery O ptimizer. SEFRQO mitigates the cold-start problem of LQOs by continuously learning from execution feedback via a Retrieval-Augmented Generation (RAG) framework. We employ both supervised fine-tuning and reinforcement fine-tuning to prepare the LLM to produce syntactically correct and performance-efficient query hints. Moreover, SEFRQO leverages the LLM's in-context learning capabilities by dynamically constructing prompts with references to similar queries and the historical execution record of the same query. This self-evolving paradigm iteratively optimizes the prompt to minimize query execution latency. Evaluations show that SEFRQO outperforms state-of-the-art LQOs, achieving up to 65.05% and 93.57% reductions in query latency on the CEB and Stack workloads, respectively, compared to PostgreSQL.

Query optimizers are crucial for the performance of database systems. Recently, many learned query optimizers (LQOs) have demonstrated significant performance improvements over traditional optimizers. However, most of them operate under a limited assumption: a static query environment. This limitation prevents them from effectively handling complex, dynamic query environments in real-world scenarios. Extensive retraining can lead to the well-known catastrophic forgetting problem which reduces the LQO generalizability over time. In this paper, we address this limitation and introduce LIMAO (Lifelong Modular Learned Query Optimizer), a framework for lifelong learning of plan cost prediction that can be seamlessly integrated into existing LQOs. LIMAO leverages a modular lifelong learning technique, an attention-based neural network composition architecture, and an efficient training paradigm designed to retain prior knowledge while continuously adapting to new environments. We implement LIMAO in two LQOs, showing that our approach is agnostic to underlying engines. Experimental results show that LIMAO significantly enhances the performance of LQOs, achieving up to a 40% improvement in query execution time and reducing the variance of execution time by up to 60% under dynamic workloads. By leveraging a precise and self-consistent design, LIMAO effectively mitigates catastrophic forgetting, ensuring stable and reliable plan quality over time. Compared to Postgres, LIMAO achieves up to a 4× speedup on selected benchmarks, highlighting its practical advantages in real-world query optimization.

Multi-access Edge Cloud (MEC) networks are powerful for providing emerging computation-intensive and latency-sensitive applications with low latency leveraging ubiquitous edge devices. These networks enable complex applications to be split into multiple components/subtasks and deployed among multiple edge servers with limited computation and communication resources. However, multiple subtasks within an application are dependent on each other. They cannot be executed in parallel, resulting in non-trivial resource waste when allocating resources to every subtask throughout the lifetime of the application. This paper investigates the multi-component task offloading problem in MEC networks that addresses the dependencies among components and three-dimensional (3D) resource allocation, i.e., computation, communication, and time slots. The problem is NP-hard and challenging to solve due to the complex task dependencies, including triangular dependencies among multiple subtasks and the routing of edges between dependent subtasks. To address the challenge, we first propose a non-destructive task reconfiguration algorithm that transforms a task call graph into multiple sequential layers, breaking out the triangular dependency. Then, we develop a dePendency-awaRe task offloAding algorithm wIth taSk rEconfiguration (PRAISE) algorithm to maximize the total offloading benefit.PRAISEdecouples the original problem into task offloading and 3D convex resource optimization. Simulation results show thatPRAISEoutperforms baselines with higher system benefits and lower resource costs.

Cloud Computing (CC) is powerful for the computation offloading of services, promoting the implementation of various modern applications. Mobile Edge Computing (MEC) can provide low-latency services utilizing edge servers locating in proximity to users. The combination of MEC and CC can give play to the dual advantages of both. However, it is a challenging problem to offload service requests to the collaborative edge-cloud networks aiming at minimizing costs due to the resource limitation of edge servers and the online feature of services. To address this issue, we mathematically model the service requests with multiple inter-connected functions. Then, the problem of computation offloading of multi-function service requests in collaborative edge-cloud networks is formulated to be an Integer Linear Programming (ILP) and is proved to be NP-hard. Furthermore, a Cost-minimized Computation Offloading with Reconfiguration (CCOR) algorithm is proposed to minimize the total cost of online services. Finally, simulation results show that the proposed CCOR algorithm can effectively reduce the cost of computation offloading with higher resource utilization of edge cloud compared with baseline algorithms.

Passive Optical Network (PON) is a cost-effective way to become the front haul carrier for 5G ubiquitous wireless access connectivity. To hide the difference of frame formats and multiplexing methods among WiMAX, LTE and WiFi, a typical PON is proposed based on Orthogonal Frequency-Division-Multiplexing Access (OFDMA), i.e., OFDMA-PON. In OFDMA-PONs, by virtualization, low-bitrate Virtual Subcarriers (VSs) are assigned to segments, and VS loads can be migrated from one segment to another, thus sleeping unloaded segments while ensuring the service continuity. Although the subcarrier scheduling has been discussed for the OFDMA-PON merged with LTE, it is tailored to the single segment without allocating time and modulation level. In this paper, we investigate joint allocation of time, VS and modulation for 5G green OFDMA-PONs. We formulate the problem aimed at maximizing the energy-saving effect, and the upper bound is also derived. To solve the problem in a short span of time, we propose a novel heuristic algorithm. Finally, an extensive simulation is made to demonstrate the effectiveness of our design.