Coherence aggregation query

Coherence is an In Memory Data Grid (IMDG) product that can be used to store and process large amounts of data in distributed environments. Coherence provides rich aggregation query functions. Here are some common aggregation queries and their examples: 1. Count: Used to calculate the number of elements that meet specific conditions. For example, suppose we have a table called 'Person' that contains an integer field called 'age'. We can use the following code to calculate the number of people aged 18 and above: NamedCache<String, Person> cache = CacheFactory.getCache("Person"); Filter ageFilter = new GreaterFilter("age", 18); int count = cache.aggregate(ageFilter, new Count<>("age")); 2. Sum: Used to calculate the sum of specified fields. Continuing to use the 'Person' table above, we can use the following code to calculate the total age of everyone: NamedCache<String, Person> cache = CacheFactory.getCache("Person"); int sum = cache.aggregate(AlwaysFilter.INSTANCE, new Sum<>("age")); 3. Average: Used to calculate the average value of a specified field. Continuing to use the 'Person' table above, we can use the following code to calculate the average age of everyone: NamedCache<String, Person> cache = CacheFactory.getCache("Person"); double average = cache.aggregate(AlwaysFilter.INSTANCE, new Average<>("age")); 4. Maximum and Minimum Values: Used to find the maximum and minimum values for the specified field. Continuing to use the 'Person' table above, we can use the following code to find the maximum and minimum age individuals: NamedCache<String, Person> cache = CacheFactory.getCache("Person"); Comparable<?> minAge = cache.aggregate(AlwaysFilter.INSTANCE, new Min<>("age")); Comparable<?> maxAge = cache.aggregate(AlwaysFilter.INSTANCE, new Max<>("age")); 5. Grouping: Used to group according to specified fields and calculate the aggregation results for each group. Continuing to use the 'Person' table above, we can use the following code to group by gender and calculate the total number of people in each group: NamedCache<String, Person> cache = CacheFactory.getCache("Person"); EntryAggregator<String, Person, Integer> groupByGender = GroupAggregator.groupBy(new Extractor<>("gender"), new Count<>()); Map<String, Integer> groupCounts = cache.aggregateEntries(groupByGender); It should be noted that the table structure and sample data in the above examples are simplified for convenience and are not specific requirements of Coherence. You can design and use the table structure and data in Coherence according to your business needs.