这篇paper介绍了HyPer是怎么执行window function的计算的,其实现的思路与Oracle的扩展partition key有所不同,而且可以做到针对不同类型window定义,不同输入数据分布,都可以很好的并行化计算,算法本身具有通用性,因此还是很有参考意义的。 介绍 Window function是OLAP的查询中比较常见的SQL construct,提供了“引用临近区域元...
SELECTfunction_nameOVER(window_definition)FROM(...) window_definition是定义要计算的记录集合,就像是一个小窗口,在整体数据集合上显示出一部分 function_name指定了对于窗口中的数据集合执行什么计算 回头看下上面的那个查询,需要计算每部电影所在年份的所有电影平均评分,下面使用窗口函数来处理 代码语言:javascript 代...
staticWindowFunction.FromPolicy[]WindowFunction.FromPolicy.values() Returns an array containing the constants of this enum type, in the order they are declared. Methods inoracle.javatools.db.sqlwith parameters of typeWindowFunction.FromPolicy
.process(newMyProcessWindowFunction());/* ... */publicclassMyProcessWindowFunctionextendsProcessWindowFunction<Tuple2<String, Long>, String, String, TimeWindow> {@Overridepublicvoidprocess(String key, Context context, Iterable<Tuple2<String, Long>> input, Collector<String> out){longcount=0;for(T...
SELECTcountry_id,season,date,AVG(home_goal)ASavg_homeFROMmatchGROUPBYcountry_id;/*ERROR: column "match.season" must appear in the GROUP BYclause or be used in an aggregate function*/ 要想将未聚合和分组的字段与聚合值比较,可以先用子查询查询聚合值在作为结果标量加入主查询 ...
It just happens to be that Oracle Database has aRATIO_TO_REPORTfunctionthat computes the ratio of a value to the sum of a set of values. In other words, there already is a window function to calculate the percentages. So the above query can be further simplified to the following, saving...
窗口函数 Window Functions:在窗口数据中执行的计算逻辑,可以是ReduceFunction、AggregateFunction或ProcessWindowFunction中的一个 触发器 Trigger:指定窗口被认为已准备好应用窗口函数的条件,如当窗口中的元素数量超过4时、当水印经过窗口的结束时间 每个WindowAssigner都带有一个默认Trigger。 如果默认触发器不符合您的需求,...
The Oracle rank() function and the PostgreSQL rank() function provide the same results.Oracle:SELECT department_id, last_name, salary, commission_pct, RANK() OVER (PARTITION BY department_id ORDER BY salary DESC, commission_pct) "Rank" FROM employees WHERE department_id = 80; DEPARTME...
Oracle Warehouse Builder - Version 11.2.0.3 and later: "ORA-30483: window functions are not allowed here" When Trying To Execute Migrated OWB Mappings In ODI
6. The method of claim 1, wherein the distribution key further comprises one or more of partition-by keys other than the partition-by key, or order-by keys other than the order-by key. 7. The method of claim 1, wherein said window function is a ranking window function. 8. The meth...