Globals

During my search for a snapshot of a persistent object,
I met a feature that I would like tho share as it could be useful in some special situations.
My trigger was to have a before- and an after-image during unit testing.

I' m facing the problem to take a Snapshot of an object.
Like a Clone but to a different Storage.

I'm looking for some existing solutions to compare 2 global structures.

- by subscripts
- if subscripts match then by content.

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Hi all, 

I am trying to create a method to count the number of entries in a global, including all subscripts. I am having a bit of trouble getting the code to make it to the second subscript. When I get to the position where my key is "Canada" and I add a comma and empty quotes to it, it returns USA as the new key when I do the order function. Is the $Order or the global not able to use a single string to represent multiple subscripts?

Here is my global structure:

I am still working on a generic task where I need to apply journal file records to another database. Initially I didn't want to use Journal.Restore class methods as I need to perform some data transformation, and it seemed that the clearest way to achieve it was to read journal file record by record using %SYS.Journal.Record API. 

Hi Developers!

InterSystems IRIS stores everything in globals and if we use ObjectScript classes to persist data class documents globals it uses in storage. But if you use globals for calculations, temporary storages, for special indexes or for some other purposes - how do you document it?

Possible options which come to my mind:

1. Macro

#define Array ^MyGlobal

usage:

s $$$Array(1)=1

2. Class parameter

Parameter Array ="^MyGlobal";

Usage:

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Hi there

Would you please advise how to count how many keys are duplicated in global, for example, Athens was duplicate 3.

When I start talking about InterSystems IRIS with more technically-minded people I always talk about how at the root of things it is a multimodel DBMS.

In my opinion that is the main advantage (on the DBMS side).

You want some sort of summary for your data? Use SQL!

Do you want to work extensively with one record? Use objects!

Want to access or set one value and you know the key? Think again. Use globals!

And the data is stored only once. You just choose the way you want to access it.

On the first overview it's a nice story - short and concise and it gets the message across, but when people really start working with InterSystems IRIS the questions start.

How are classes and tables and globals related? What are they to each other? How's data really stored?

In this article I would try to answer these questions and explain what's really going on.

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:

Suppose we need to store millions of values temporarily, that means, we don't care about them if we lose them but our application use them to get realtime information. Should I use Cachetemp or whatever other DB without journaling enabled? If answer is Cachetemp, shouldn't be a problem if we decide to scale using App Server + ECP? I'm not sure what would happen with the app logic in such architecture as I guess I couldn't map and share cachetemp...

Any idea/suggestion?

Hi,

Most of my classes are mapped from Globals. I want to access Cache classes from a BI software through ODBC connection.

'Last update' information does not exist in most of the classes. My question is whether there is a 'last update' timestamp that is automatically generated for each line in classes I can extract to external systems?

Thanks

Hi,

I've read into console.log that there is some problems writing the global Task History

09/13/18-09:33:00:109 (9052) 0 Error al escribir en global de historial de tareas - Error (ERROR #5002: Error de cache: <DATABASE>%SaveData+20^%SYS.Task.History.1 ^SYS("Task","HistoryD",66179),c:\intersystems\healthshare\mgr\)