Globals are multidimensional sparse arrays which are stored in InterSystems Data Platform. Everything in InterSystems Products is stored in Globals: Classes, Tables, Documents, Code.
I'd like to share with you some storage features that also exist in Caché but are almost unknown and mostly not used. They are of course available in IRIS and gain importance with large and distributed storage architectures.
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
Standard error logs in IRIS / Caché / Ensemble are written global ^ERRORS. As this piece dates back some decades back to previous millennium its structure is far from the typical SQL storage structures.
Every now and then you may encounter a situation where for various reasons ODBC is the only option to access a remote system. Which is sufficient as long as you need to examine or change tables. But you can't directly execute some commands or change some Global.
Special thanks @Anna Golitsyna for inspiring me to publish this.
In this article you will have access to the curated base of articles from the InterSystems Developer Community of the most relevant topics to learning InterSystems IRIS. Find top published articles ranked by Machine Learning, Embedded Python, JSON, API and REST Applications, Manage and Configure InterSystems Environments, Docker and Cloud, VSCode, SQL, Analytics/BI, Globals, Security, DevOps, Interoperability, Native API. Learn and Enjoy!
If you define a Persistent Class / Table the class compiler generates for you an appropriate Storage definition. A different option is to define a SQL mapping for an already existing Global storage. This has been excellently explained already in a different series of articles. The Art of Mapping Globals to Classes 1 of 3
For those of you who might be new to IRIS, and even those who have used Cache or IRIS for some time but want to explore beyond its usually-assumed boundaries and practices, you might want to dive into this detailed exploration of the database engine that is at its heart, and discover just what you can really do with it, going way beyond what InterSystems have done with it for you.
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”).
M:N Relationship is a recurring object of my interest for a long time. So the subject turns up with me repeatedly. For this article, I found a nice example with TWO separate M:N relationships. Some M:N².
It is not pure fiction but taken from a closer view of OEX Contests that we run on a regular base.
If you are looking to breathe new life into an old MUMPS application follow these steps to map your globals to classes and expose all that beautiful data to Objects and SQL.
If the above does not sound familiar to you please start at the beginning with the following:
In most cases, a global used by default storage has just 1 subscript level that represents the IDKEY. For an index-globals we may see 2 or more subscript levels. Arrays, or parent-child relationships or persistent classes extending a base data class are examples where we see more levels. Though all these globals are quite uniform.
For some years I missed being able to offer, to everybody interested in ObjectScript, a tutorial more or less complete, to start with ObjectScript. Something that could help more and make things easier to those new developers that come to our technology... something intermediate, halfway between the common "Hello World!", that doesn't really get you further, and the "Advanced Training", that is unaffordable because of lack of time,etc.
If there were something truly helpful not only as an introduction to the ecosystem, but as a starting point, as a boost, to really start to walk into ObjectScript and move forward by yourself... wouldn't that be awesome?
In general Global Streams are data objects embedded in Classes / Tables. Using and viewing them with SQL is normally a part of the access to the containing tables.
SO WHAT?
During debugging or searching for strange or unexpected behavior there could be the need to get closer to the stored stream. No big problem with direct access to Globals with SMP or Terminal. But with SQL you are lost. So my tool provides dynamic access to Global Streams wherever you may need this Special thanks to @Oliver Wilms for the inspiration for this tool.
The similarity between JSON objects + arrays and Globals in IRIS or Caché is evident. With small and medium size JSON objects navigation across %Dynamic Objects is comfortable. But with large and/or deep cascaded objects it becomes a challenge.
The presented tool offers 3 variants
loading an already existing %Dyamic object or Array into a global of your choice
loading a %Stream containing a JSON object into a global of your choice
loading an external File containing a JSON object into a global of your choice
InterSystems IRIS currently limits classes to 999 properties.
But what to do if you need to store more data per object?
This article would answer this question (with the additional cameo of Community Python Gateway and how you can transfer wide datasets into Python).
The answer is very simple actually - InterSystems IRIS currently limits classes to 999 properties, but not to 999 primitives. The property in InterSystems IRIS can be an object with 999 properties and so on - the limit can be easily disregarded.
The forth in the trilogy, anyone a Hitchhikers Guide to the Galaxy fan?
If you are looking to breathe new life into an old MUMPS application follow these steps to map your globals to classes and expose all that beautiful data to Objects and SQL.
If the above does not sound familiar to you please start at the beginning with the following:
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:
It's well-known that namespace global mapping helps us to write code independent on database storage details (Caché instance name, directory path). But sometimes we can face problems accessing an unsubscripted global which has subscript level mapping (SLM) defined. Most of such cases are evident and associated with administrative tasks that should be done on database level, but some of them can confuse even an experienced developer. Just to start:
Since I started to use internet (late 90's), I always had a CMS (content management system) present to make easier post
any information in a blog, social media or even an enterprise page. And later years putting all my code into github I
used to document it on a markdown file. Observing how easy could be persisting data into Intersystems IRIS with the
Native API I decided to make this application and force myself to forget a little of SQL and stay open to key-value database
model.
I'm participating in the Developing with InterSystems Objects and SQL with Joel Solon. The course is very nice and I will share with you some tips I got during the training. Tips presented in the day 4:
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