#Globals

Those of you that worked already with ECP might know that it operates not only across
operating systems, processor technologies (big-little-endian), but also -with limits- across versions in C/E.
This cross-version feature also includes IRIS (verified for 2020.1)  and C/E (2018.3)

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?

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.

Is there something in Cache that is equivalent to partitioning a table in Oracle? I'm trying to break some big tables into groups so that the most frequently accessed data is faster to retrieve.

Here is some information on this concept from Oracle.

https://docs.oracle.com/cd/B28359_01/server.111/b32024/partition.htm

I have a classname and a property name. I want to know, when I get object value directly from a global, which property corresponds to which position in the $lb structure.

Here's what I got so far:

Class Utils.Storage {

/// write ##class(Utils.Storage).GetPosition()
ClassMethod GetPosition(class As %Dictionary.CacheClassname = "Sample.Address", property As %Dictionary.CacheIdentifier = "Zip") As %Integer
{
    set strategy = $$$comClassKeyGet(class, $$$cCLASSstoragestrategy)    
    set strategyId  = class _ "||" _ strategy
    &sql(SELECT Name INTO :position
         FROM %Dictionary.

What is the best way to get the size and other storage details of individual Globals in a namespace? 

Thanks,

Mary

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?

A simple question: View Global Data  page shows globals always in ascending subscript order. Very often I need to see latest page, is there any trick for this?

Update: I mean to see last subscripts in Management Portal, not using the code

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.

For example, RoutineB() would be able to access ^Global(1) and ^Global(1,2) since RoutineA() utilized them, but RoutineB() would have to read ^Global(1,7) from disk as it was not utilized by RoutineA().

We are trying to create a simple class extending %RegisteredObject that could be used as a singleton. However we are not able to store it in a global to later be retrieved (by the same process but elsewhere in the code).

I resumed my issue in this small code sample : 

ClassMethod RunMe()
{
   // Create a simple %RegisteredObject
   set obj = ##class(%ZEN.proxyObject).%New()
   set obj.MyProp = 22
   do ##class(%SYSTEM.OBJ).Dump(obj)
   
   // Store it in a global
   set ^MyGlobalName = obj
   write "Stored : " _ obj,!!
      
   // Retrieve it from the global
   #Dim obj2 As %ZEN

Hello Community,

Is it possible to track or determine where the global variable was set (routine or class) in a form of like label+offset^routine?

Regards,

Ashok

Dear people,

I (really) spent hours on finding the maximum size a Global is allowed to be (for Windows, if that matters). All I seem to run into are database sizes (derived from a max number of blocks and block size), but I refuse to believe that is correct because too small to be realistic.  

It will  undoubtedly my fault that I don't understand or misread the concepts of "database" vs Globals, envisioning files as such while one set of functional Globals in one file (?

Some of our interfaces use globals for lookups, but we are currently looking at putting a groups of (document) interfaces in a separate production with a shared ‘Default Database for Routines’ to reduce code duplication.

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?

Is there a way to pull a user name and password from the Credentials list that is kept in Ensemble? Right now I have a LDAP user that I have hard coded into my ZAUTHENTICATE, which I would like to get away from. I am not to familiar with settings Global, or calling them at least.

Thanks

Scott

In Caché, it's possible to iterate a local array using $QUERY() :

set a("foo") = 50
set a("bar") = 30

set key = "a"
for
{
     set key = $QUERY(@key)
     quit:key="" 
     write key_" = "_@key
}

This code works perfectly, unless it's called in a job (eg: a routine called by the JOB command).

In that case, $QUERY will return an empty string. It's like the array cannot be referenced anymore by simply using it's name.
It works using $ORDER(a("")) but I would like to use $QUERY if possible (because my array has several dimensions and it would require several for loops).

Hello community!

I'm facing a base growth issue, which is being generated by a process and an Ensemble feature.

When executing the process of cleaning up the message queues, the Ensemble “preserves” the Streams that were part of these messages, deleting only the Header and Body. In this way the database (of one of the namespaces) has grown around 60GB per day, which has been maxing out the disk capacity.

InterSystems informed that this is a characteristic and that it is explained in the documents mentioned below.

https://community.intersystems.

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. 

I mean, if the instance only runs productions that pass messages then the 90% of the global access is used for persist the messages.

If a global node contains special characters, (eg : a line returns), it will be displayed like this in Portal ("System > Globals > View Global Data" panel) :

^A(1) = "this is"_$c(13,10)_"a test"

I would like to export global data to a txt file using a similar format.

I already wrote the main code (that loops on all nodes and dump them to file), the problem is how to handle special characters.
For the moment I replace them manually one by one. It works, but it's far from perfect :

set text = .

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\)

Hi all,

I need to create a routine to modifiy some values in a global.

My first attempt was:

but if I use a *.bas file (cache basic script), I'm not able to use these commands ($Order and $Next) and I don't know how to translate theses words.

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.

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 All, I need the what are all the global having subscript and value contain what I have the value.How to find out?

Is there any good book where is described process of mapping globals to classes? And book about Storage? 

I didn't find much information about these questions in documentation :-(

Sometimes global mapping of the same globals can be defined in different ways. E.g., I need to define it for 3 globals ^qAuditC, ^qAuditLog, ^qAuditLogC from the same database named APP-NOJOURN. Which approach should be better from the performance point of view?

1) qAudit* => APP-NOJOURN (one record in global mapping table)
or

2) qAuditC => APP-NOJOURN
qAuditLog => APP-NOJOURN
qAuditLogC => APP-NOJOURN (three records in global mapping table)

From one hand, the less records in global mapping table, the better. From other hand, * can cause additional processing at run time.

I found the thread that discusses object mapping, in particular mapping a common global among more than one namespace. The example that is given is a simple one when it's ^global(sub1, ^global(sub2, etc. However I'm having trouble getting this to compile/work when the global has a fixed subscript amongst variable ones.

I have this global in namespaces LAB and ARK in the following format:
^CB(1,sub1)=....

^CB(1,sub2)=...

^CB(1,sub3)=...

Here is what I have

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

Hello Intersystems-Community,

I build an API and there I use $order to get the Data from my Globals.
When I first time use that API it's get an error (504 Gateway-Timout > 60 Sec.).

After 2 reloads it works with a loading time of 2 Sec.! Sounds for me like the $order is cached and it works faster. Is it true $order will be cached?

When it works, I only get the error at the next day. So it's very hard to reproduce that error.

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.