A recent technical analysis on CSDN highlights a critical divergence in Chinese database optimizers: how they handle DISTINCT queries. The author argues that some optimizers rely on cost models to decide execution plans, while others use formal proof techniques to derive optimal paths. This distinction, often hidden in benchmark comparisons, becomes visible under DISTINCT because it forces the optimizer to choose between sorting, hashing, or early aggregation. The post references specific behaviors in open-source Chinese databases like OceanBase and TiDB, though without naming them directly. For engineers building or tuning query engines, this signals that Chinese database systems are developing unique optimization philosophies rather than simply cloning Western designs. The practical implication is that query performance on Chinese databases may behave unpredictably for DISTINCT-heavy workloads, requiring specialized tuning knowledge.
Analysis of how Chinese database optimizers handle DISTINCT reveals a split between cost-based and proof-based strategies.