A key-value data model, or key-value store, is a data storage paradigm designed for storing, retrieving, and managing associative arrays, a data structure more commonly known today as a dictionary or hash. Dictionaries contain a collection of objects, or records, which in turn have many different fields within them, each containing data InterSystems Data platform supports key-value concept of data management.
In the prior part of this series we have provided introduction to Google MapReduce approach, but still not covered their possible ObjectScript implementation. Which we will start to explain today.
In the previous parts (1, 2) we talked about globals as trees. In this article, we will look at them as sparse arrays.
A sparse array - is a type of array where most values assume an identical value.
In practice, you will often see sparse arrays so huge that there is no point in occupying memory with identical elements. Therefore, it makes sense to organize sparse arrays in such a way that memory is not wasted on storing duplicate values.
In some programming languages, sparse arrays are part of the language - for example, in J, MATLAB. In other languages, there are special libraries that let you use them. For C++, those would be Eigen and the like.
Globals are good candidates for implementing sparse arrays for the following reasons:
We're developing Ensemble PoC and one day our frontend developer (who doesn't have Ensemble production running) said that Populate just doesn't cut it and he needs to see the real data. He needed only one object, but the problem was - it's a big object. Still, I checked ids of everything related and wrote this command (parts omitted, but you get the idea):
I have a lookup table and record batch Table I would like to do a count on the records stored in that batch by counting the number of records in that batch that have a certain key on the responseKey column. This column keys are stored in the look up table for comparison. So I would like to do a join sql pivot that will use my keys stored in the lookup as columns and count as values
so far I have managed to do this but this is not efficient I would like to fire that sql once not on every count
PHP, from the beginning of its time, is renowned (and criticized) for supporting integration with a lot of libraries, as well as with almost all the DB existing on the market. However, for some mysterious reasons, it did not support hierarchical databases on the globals.
Globals are structures for storing hierarchical information. They are somewhat similar to key-value database with the only difference being that the key can be multi-level:
Though the access is quite comfortable (in traditional COS sense) there are 2 main restrictions that hurt:
#1) It is not saved to disk unless your application includes code to save it specifically. #2) It cannot be stored in or exposed through SQL tables there are some more I'll show how to overcome these limits
While the classic solution followed rather close the concepts and design of the ancestors Caché / IRIS allows a more modern approach to flexible/multidimensional properties
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In the previous parts (
PHP, from the beginning of its time, is renowned (and criticized) for supporting integration with a lot of libraries, as well as with almost all the DB existing on the market. However, for some mysterious reasons, it did not support hierarchical databases on the globals.
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