Deduplicating at query time can be achieved by grouping the data on the fields, which uniquely identify a row, and using the argMax function with a date field to identify the last value for other fields. ReplacingMergeTree allows rows with the same sorting key (ORDER BY key) to be deduplicated on merges. Note this is "best effort" only: sometimes parts will not be merged with the merge process scheduled at non-deterministic intervals. It, therefore, does not guarantee the absence of duplicates. Users can also utilize the FINAL modifier to force this deduplication at SELECT time. While FINAL does add overhead, it has received significant performance improvements in recent versions including multi-threaded processing, and is suitable for many production workloads.
“无论是韩国的进步派政府还是保守派政府，领土主权问题的重要性要高于美日韩三边军事合作。只有尹锡悦政府是个例，选择搁置这一问题的争议。”王箫轲表示。
。业内人士推荐新收录的资料作为进阶阅读
“我对这些铁疙瘩是有感情的。解决一个难题，那个成就感，比吃啥都香。”3月5日，首场“代表通道”上，中国一汽研发总院首席技能大师杨永修代表深情讲述。
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