Globals

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Hi,

I have a class with around 400k lines and 60 columns. Class storage is Cache SQL storage (Mapped from a global).

 I want to create multiple indices on certain fields.

I am familiar with two approaches:

1. Create a new map (Index type) on a pointer global.

2. Create a bitmap index

Which approach is more recommended to be used in the case I described? If there are any other approaches, I will be happy to hear.

Thanks :)

 

Last answer 11 October 2017 Last comment 19 October 2017
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Is there a way to omit or skip rollback of some data changes during a transaction rollback? Maybe some sort of "autonomous transaction"?

The issue is with error logging in transaction. For example we may have in nested calls the following structure:
TS
<some code>
<error happens>
TRO 1
<error log to database>

but if this code is in another transaction, and that rolls back we lose error data.

Last answer 28 August 2017 Last comment 25 August 2017
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Have very little XML experience and have been able to manually create output. Have a need to take data that I store in a M global (example: ^TML("HDATA", ) and out put it in CCDA XML format.

Are there any examples of M code using the XMLWriter to accomplish this?

Or can anyone provide some guidance 

Any help would be greatly appreciated.

Last answer 2 August 2017
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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.

Last comment 31 July 2017
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Greetings,

If given a global, how can I discover information on that global?  More specifically,  how can I discover how many indices it contains?  ie:  ^G(1,2,3,4,5)   How can I discover that there are 5 subscripts within the Global ^G if I did not already know.

Please advise, and thanks in advance for everyone's time.

Last answer 17 July 2017 Last comment 17 July 2017
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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.

Last answer 12 July 2017 Last comment 17 July 2017
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Beginning - see Part 1.

 

3. Variants of structures when using globals

 

A structure, such as an ordered tree, has various special cases. Let's take a look at those that have practical value for working with globals.

 

 

 

 

3.1 Special case 1. One node without branches

 

Last comment 8 July 2017
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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:

Last answer 3 July 2017 Last comment 4 July 2017
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I know the process ID< and I know the global name: ^||testing(index).  From the terminal (and therefore, and different process ID), how do I view the contents of ^||testing() ?  Not the list of process private globals; the contents of this single PPG.

Thanks,

Laura

Last answer 12 June 2017 Last comment 12 June 2017
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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. 

 

Last answer 30 May 2017
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The Art of Mapping Globals to Classes  (2 of 3)

 

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.

 

This example is going to cram in 4 or 5 different things beyond what was covered in Part 1 

Last comment 23 May 2017
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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.

Last comment 16 May 2017
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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. 

Last answer 3 April 2017 Last comment 5 April 2016
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Hi, Community!

Is there an option to get an archived file of globals in one command. Say for:

Do $System.OBJ.Export("Class1*D.GBL,Class2*D.GBL","data_gbl.xml")

get something like:

Do $System.OBJ.Export("Data*D.GBL","data_gbl.gz","gzip")

And also to have the convenient one click way to  import it to the namespace via terminal or Control Panel?

If anyone already has this module, share please?

It would be very convenient for import/export/continuous integration purposes cause globals can be really heavy.

 

Last answer 1 April 2017 Last comment 1 April 2017
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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.

Last answer 23 March 2017 Last comment 9 January 2017
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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...

Last answer 6 February 2017 Last comment 7 February 2017
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Can someone direct me to where in the documentation we can find how consumption may be calculated for global storage?

Caché Version2010.1
Operating SystemHP OpenVMS 8.4

 

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.

Last answer 23 January 2017 Last comment 23 January 2017
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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.

Last answer 29 December 2016 Last comment 29 December 2016
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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.

Last answer 28 December 2016 Last comment 28 December 2016
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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.

Last answer 6 December 2016 Last comment 6 December 2016
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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:

Last comment 1 November 2016
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Now, let’s say you can’t access the terminal or simply you just rather execute it from a web interface. In this article, I will show you how to execute terminal commands from a simple web page.

For example, in the image below you see how we execute $zv on a webpage:

Last comment 13 October 2016
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