#Globals

These Globals are usually cleared out as part of the startup/shutdown processes. If your server never reboots how would you clean these out?

Does anyone know of a utility to compare two databases (i.e., CACHE.DAT files) and find globals/subscripts that are different between them?

If not, I'll write one and share it.

Hi,

I use cache 5.0 and access cache through OpenVMS.

The disk-space under a particular namespace has grown up in size due to cache.dat. How to recreate cache.dat to bring up more space back on disk?

Hi, colleagues!

Consider you need to put some (less than 1GB) data to an indexed array and do some data manipulations and calculations with it.

Should I prefer global or local for it?

Is there any general rule when local is faster than global and vice-versa?

Globals, these magic swords for storing data, have been around for a while, but not many people can use them efficiently or know about this super-weapon altogether.

If you use globals for tasks where they truly shine, the results may be amazing, either in terms of increased performance or dramatic simplification of the overall solution (1, 2).

Globals offer a special way of storing and processing data, which is completely different from SQL tables. They were first introduced in 1966 in the M(UMPS) programming language, which was initially used in medical databases. It is still used in the same way, but has also been adopted by some other industries where reliability and high performance are top priorities: finance, trading, etc.

Later M(UMPS) evolved into Caché ObjectScript (COS). COS was developed by InterSystems as a superset of M. The original language is still accepted by developers' community and alive in a few implementations. There are several signs of activity around the web: MUMPS Google group, Mumps User's group), effective ISO Standard, etc.

Modern global based DBMS supports transactions, journaling, replication, partitioning. It means that they can be used for building modern, reliable and fast distributed systems.

Globals do not restrict you to the boundaries of the relational model. They give you the freedom of creating data structures optimized for particular tasks. For many applications reasonable use of globals can be a real silver bullet offering speeds that developers of conventional relational applications can only dream of.

Globals as a method of storing data can be used in many modern programming languages, both high- and low-level. Therefore, this article will focus specifically on globals and not the language they once came from.

It is my understanding that when a routine accesses a global it is temporarily stored in global memory. While the global is within global memory, any other routine would be able to readily access the global from memory and not from disk so long as the same node is being utilized.

Good day, I have this issue. I have global like: ^myglobal(varX) = $LB(var1,var2). I need to delete all globals that have variable var1 in that list same without a need to iterate through all globals and checking their value.

Exact example:

- in database exist following:

I am inserting rows in a table. This table is appearing in all namespace as I did global mapping.

So once I run insert command from a method, it insert the rows. When I run the same insert command from other namespace, it replace the existing data in table.

Insert command is same in all namespace but the data I m inserting is different.

Hi Everyone,

Link to webinar recording: https://learning.intersystems.com/course/view.php?id=623

Thank you for your interest in this webinar!

Please submit questions about the content of the webinar as comments below this article.

Usually I recommend to set the global buffer (GB) as large as possible in order to maintain in memory more globals as possible. I don't know if this is a standard recommendation, but I want to discuss what should be the best buffer size for a Ensemble instance that only process messages.

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.

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...

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.

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.