#Object Data Model

This article was written as an attempt to share the experience of installing the InterSystems Caché DBMS for production environment.
We all know that the development configuration of a DBMS is very different from real-life conditions.
As a rule, development is carried out in “hothouse conditions” with a bare minimum of security measures, but when we publish our project online, we must ensure its reliable and uninterrupted operation in a very aggressive environment.

Quotes (1NF/2NF/3NF)^ru:

Every row-and-column intersection contains exactly one value from the applicable domain (and nothing else).
The same value can be atomic or non-atomic depending on the purpose of this value. For example, “4286” can be

• atomic, if its denotes “a credit card’s PIN code” (if it’s broken down or reshuffled, it is of no use any longer)
• non-atomic, if it’s just a “sequence of numbers” (the value still makes sense if broken down into several parts or reshuffled)

This article explores the standard methods of increasing the performance of SQL queries involving the following types of fields: string, date, simple list (in the $LB format), "list of <...>" and "array of <...>".

Here's one way to determine if a class is mapped (i.e. it is in a package whose definitions come from a database other than the default code database for the current namespace):

SAMPLES>w ##class(%Library.RoutineMgr).IsMapped("Cinema.Film.cls")
0
SAMPLES>w ##class(%Library.RoutineMgr).IsMapped("%iKnow.Objects.Source.cls")
1
SAMPLES>

If you pass a by-ref second argument to IsMapped you can also discover what database the class definition is stored in:

Here you have an easy way to write and execute COS code from your unix scripts. This way one does not need to write routines or even open Studio or Atelier. It can be an option for simple and small actions for instance things like installation tasks or compiling.

See sample bash script (compile.sh) to compile classes:

Today, I was reading some source code, and encountered the following method signature:

Method SendRequestSync(pRequest As %Library.Persistent, ByRef pResponse As %Library.Persistent)

And I immediately thought, why is there a ByRef?

In most cases, if one class depends on another, the class compiler will detect this and determine the correct compilation order. For example:

Object Synchronization is a feature that has been around for a while, since Caché days, but I wanted to explore a bit more how it works. I've always thought that database automatic synchronization is complex by nature but, for some particular scenarios shouldn't be so hard. So I considered a very simple use case (OK, perhaps the typical one, I'm not discovering anything... but if it's common and it works, it's good ).

Often when debugging COS code you get an error message such as '<UNDEFINED>test^routine *test' so the first thing you want to do is to take a look at this code and see what it is doing. From the command line you can:

The Art of Mapping Globals to Classes (4 of 3)

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:

The Art of Mapping Globals to Classes (1 of 3)

Following up on the topic of making sure that referenced instances are deleted when the referrer is deleted –

In part I of this series we have introduced MapReduce as a generic concept, and in part II we started to approach Caché ObjectScript implementation via introducing abstract interfaces. Now we will try to provide more concrete examples of applications using MapReduce.

InterSystems FAQ rubric

By specifying the start and end values ​​of the IDs for which you want to rebuild indexes in the arguments of the %BuildIndices() method provided in the persistent class (=table) definition, you can rebuild only the indexes within that range.

1. Don’t use Python built into Mac. Because of System Integrity Protection (SIP) you will not be able to access the libraries that the InterSystems Python binding requires. The Python build into the MAC has baked in what libraries it can use.
2. Install another Python. Don’t put this other ahead of Mac Python on path since this could break things. Apple regards its Python as part of the its OS, and may use that Python in its system operations.
3. This Python will not be installed into the protected area.

This is a translation of the following article. Thanks [@Evgeny Shvarov] for the help in translation.

This post is also available on Habrahabr^ru.

The post was inspired by this Habrahabr article: Interval-associative array^ru→en.

Since the original implementation relies on Python slices, the Caché public may find the following article useful: Everything you wanted to know about slices^ru→en.

Note: Please note that the exact functional equivalent of Python slices has never been implemented in Caché, since this functionality has never been required.

And, of course, some theory: Interval tree^ru→en.

All right, let’s cut to the chase and take a look at some examples.