| Abstract |
Debugging and tuning database systems is very challenging. Using common profiling tools is often not sufficient because they identify the machine instruction rather than the instance of a data structure that causes a performance problem. This leaves a problem's root cause such as memory hotspots or poor data layouts hidden. The state-of-the-art solution is to augment classical profiling with a memory trace. However, current approaches for collecting memory traces are not usable in practice due to their large runtime overhead.
In this work, we leverage a mechanism available in modern processors to collect memory traces via hardware-based sampling. We evaluate our approach using a commercial and an open-source database system running the JCC-H benchmark. In particular, we demonstrate that our approach is practical due to its low runtime overhead and we illustrate how memory traces uncover new insights into the memory access characteristics of database systems.
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