#Globals

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.

Currently, we have an application running in one namespace ("Database B") that has globals and routines mapped to another database ("Database A"). After enforcing clean up on Database A, we found that 90% of the disk is free. We would like to compact Database A and release the unused space. However, we are running OpenVMS, which seems to be the issue.

For databases consisting of only globals, we are able to use ^GBLOCKCOPY; however, we need to ensure that the routines and mappings are also copied.

What would be the best recommended way to do this?

If I were trying to access an index of a global variable, what time complexity would this operation have? My understanding of languages like Java/C++ is that arrays are stored as blocks of memory so that x[15] would have a lookup time complexity of O(1) because it just goes to (address of the array + 15) and retrieves the value stored there.

How does this work in Cache where the index of a variable isn't necessarily an integer value? If I were to have a variable like the following:

x("Adam") = "Red"

x("George") = "Blue"

x("Bryan") = "Green"

etc...

Can someone direct me to where in the documentation we can find how consumption may be calculated for global storage?

EDIT: After receiving some responses, it seems I was unclear in my initial inquiry. I am looking to determine our rate of consumption of storage; however, I am having some difficulty in doing that.

While utilizing ^%GSIZE, which is used by the %GlobalEdit class, the results appeared odd. I have provided my results below, which illustrate the global structure on the left and the usage indicated by ^%GSIZE on the right.

I want to generate a list object of routines from the ^$ROUTINE global without directly reading the [^$ROUTINE] global.

E.G. I want to create an array/variable/object with names of all routines that start with "ABC" so that an application process can use each routine name as input for a subsequent process.

Currently, namespace Alpha is configured to use database AlphaDB as its global database. How would we go about having namespace Alpha configured to use database AlphaDB for its global database except where global ^Customers(CustomerId) has a CustomerId greater than 10M, which we would like to have it redirected to database BetaDB.

In other words, ^|"AlphaDB"|Customers contains all customers between 1 and 10,000,000; and ^|"BetaDB"|Customers contains all customers greater than 10,000,000. Any help would be appreciated.

Hello.  When you export and then import a table of data, is the import smart enough to figure out if a row already exists in the new namespace, and if so update the row rather than just save/add the row?

For example, we have a table in DEV, and the same table in QA.  The DEV table has more fields than QA.  When we moved up the class, the field definitions went with the table into QA, so now the table definition is the same in both.

This post is the direct result of working with an InterSystems customer who came to me with the following problem:

SELECT COUNT(*) FROM MyCustomTable

Takes 0.005 seconds, total 2300 rows.  However:

SELECT * FROM MyCustomTable

Took minutes.  The reason for this is subtle and interesting enough for me to write a post about.  This post is lengthy, but if you scroll to the bottom I'll write a quick summary, so if you've gotten this far and think you've already read enough, scroll to the end to get the main point.  Check for the sentence in bold.

NewBie's Corner Session 27 Traversing A Global with $Order Part 1

Welcome to NewBie's Corner, a weekly or biweekly post covering basic Caché Material.

Traversing A Global

Perhaps the most difficult concept in Caché/MUMPS is its Global Structure. This session and several that follow it deals with the Global Structure. However, just presenting the material will not guarantee your understanding of it. You must experiment with the data and concepts that are presented.

In this session, we are going to create a small Global of three levels deep, and then show the code to Traverse the Global.

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):

Let's say I have a global named ^a and I need to export its nodes 1, 2, 3, 5 only.

Currently I write something like this:

Write $SYSTEM.OBJ.Export("a(1).gbl,a(2).gbl,a(3).gbl,a(5).gbl", "C:\Users\eduard\Desktop\a.xml")

Is there a way to write it shorter? I want to write global node once and list all the subscripts I need.

Let's imagine I have a global like this:

^Users(12, "SETTINGS", "IsAllowed") = 1

^Users(41, "SETTINGS", "IsAllowed") = 0

^Users(52, "SETTINGS", "IsAllowed") = 1

Now I would like to check for each user whether they are allowed, therefore I'd need to iterate through the Global. How to do that? It seems that I can't use $Order here like such:

S FF = ""
For {
 S FF=$O(^Users(FF,"SETTINGS","isAllowed"))
 Q:$L(FF)
 W "User ",FF," is allowed",!
}

Is there any other way of doing this? 

I ran %GSIZE and my ^cacheStream global is very large. How do I go about 

1. Evaluating what data is in the global.

2. Clean it up.

Thanks!

Process-private Globals  can be used as a data global in storage definition. That way, each process can have its own objects for the class with ppg storage. For example lets define a pool, which can:

• add elements to a pool (ignoring duplicates)
• check if an element exists in the pool

Here's the class:

Using Node.js with Caché - Introduction says the following:

The cache.node module is the Node.js interface for the GlobalsDB kit, which can be obtained from the GlobalsDB download page (http://globalsdb.org/downloads/). The Node.js interface can be used with either Caché or the free GlobalsDB database.
The installation kit includes detailed documentation on how to install and configure the cache.node module.

However, http://globalsdb.org/downloads gives a 404 and http://globalsdb.org just redirects to intersystems.com

Where can I find the files I need?

Order is a necessity for everyone, but not everyone understands it in the same way (Fausto Cercignani)

Disclaimer: This article uses Russian language and Cyrillic alphabet as examples, but is relevant for anyone who uses Caché in a non-English locale.Please note that this article refers mostly to NLS collations, which are different than SQL collations. SQL collations (such as SQLUPPER, SQLSTRING, EXACT which means no collation, TRUNCATE, etc.) are actual functions that are explicitly applied to some values, and whose results are sometimes explicitly stored in the global subscripts. When stored in subscripts, these values would naturally follow the NLS collation in effect (“SQL and NLS Collations”).

Is the default language (i.e., $$$DefaultLanguage, which is used as the basis for localization with $$$Text/etc. at compile time) always "en" for new Caché installations, or could it be different? How is this determined? I don't see an option to select a language during Caché installation.

Also, is there a supported/preferred API for setting the default language? Looking at %occMessages.inc, one option would be:

Set $$$DefaultLanguageNode = "en"

But I'd expect there to be a classmethod for this somewhere (and haven't managed to find it yet).