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#Object Data Model

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An object data model is that data or code is composed of modules that combine data and procedures that work on the data.

Learn more.

Hi,

this is a public announcement for the first release of Intersystems Cache Object-Relational Mapper in Python 3. Project's main repository is located at Github (healiseu/IntersystemsCacheORM).

About the project

CacheORM module is an enhanced OOP porting of Intersystems Cache-Python binding. There are three classes implemented:

The intersys.pythonbind package is a Python C extension that provides Python application with transparent connectivity to the objects stored in the Caché database.

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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:

  • add elements to a pool (ignoring duplicates)
  • check if an element exists in the pool

Here's the class:

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The source class of a DeepSee cube has a property referencing a different class:

Class ClassA Extends %Persistent {
     Property P1 As ClassB;
}

When records in class B change, the ^OBJ.DSTIME global for Class A will not be automatically updated. This means that synchronization of cubes based on source class A will not reflect the changes occurred to property P1.
This post will help you determine the best way to achieve synchronization of properties referencing a different class

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Let's say we have two serial classes, one as a property of another:

Class test.Serial Extends %SerialObject
{
Property Serial2 As test.Serial2;
}

Class test.Serial2 Extends %SerialObject
{
Property Property As %String;
}

And a persistent class, that has a property of test.Serial type:

Class test.Persistent Extends %Persistent
{

Property Datatype As %String;

Property Serial As test.Serial;

}

So it's a serial, inside a serial, inside a persistent object.

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NewBie's Corner Session 3 More Read and Write commands & Multiple commands

Welcome to NewBie's Corner, a weekly or biweekly post covering basic Caché Material.

Click on the Caché Cube in your system tray and select Terminal to try out the commands.

Write command with carriage return and line feed

When the exclamation point "!" is inserted after a Write command, a carriage return and line feed combination is produced. Note in this example, that a comma separates the exclamation point from the variable "X".

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The object and relational data models of the Caché database support three types of indexes, which are standard, bitmap, and bitslice. In addition to these three native types, developers can declare their own custom types of indexes and use them in any classes since version 2013.1. For example, iFind text indexes use that mechanism.

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

This post is also available on Habrahabrru.

The post was inspired by this Habrahabr article: Interval-associative arrayru→en.

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

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

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Article
· Feb 19, 2016 1m read
Simple WorkMgr example

Attached code contains a very basic $system.WorkMgr example.

It uses several jobs (workers) to update different chunks of rows of a table.

Steps:

  • Creates a table with 100 records.
  • Split table in chunks
  • Initialize WorkMgr and queue chunks to workers.
    • Every worker simply sets its process number in the Job field of the processed row.

In this case, I have tested the example in a 8-core laptop:

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The Management Portal allows you to Export one or more globals to a file that you can then Import into that or another namespace. However, the Management Portal can only be used to export entire globals. For exporting selected nodes or subtrees within a global, a different utility is necessary. This utility is the Export() classmethod in the %Library.Global class, which can export an entire global but also has the ability to export selected nodes or subtrees.

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Article
· Mar 2, 2017 1m read
Trusting the code you import

As more people join Developer Community, and with increasing efforts to promote code sharing, I'd like to draw fresh attention to this post I wrote a year ago. It spotlights a feature within the class compiler which is both useful and dangerous. When importing code (e.g. from an XML export of classes received from someone), it's worth considering the risks.

Even if that post doesn't seem relevant to you at the moment you may wish to note it for the future. A handy way of doing this is to click the star icon at the end of it.

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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 wink ).

Open Exchange app
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We're developing Ensemble PoC and one day our frontend developer (who doesn't have Ensemble production running) said that Populate just doesn't cut it and he needs to see the real data. He needed only one object, but the problem was - it's a big object. Still, I checked ids of everything related and wrote this command (parts omitted, but you get the idea):

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This summer the Database Platforms department here at InterSystems tried out a new approach to our internship program. We hired 10 bright students from some of the top colleges in the US and gave them the autonomy to create their own projects which would show off some of the new features of the InterSystems IRIS Data Platform. The team consisting of Ruchi Asthana, Nathaniel Brennan, and Zhe “Lily” Wang used this opportunity to develop a smart review analysis engine, which they named Lumière. As they explain:

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  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.
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Article
· Sep 28, 2017 1m read
Terminal license expire message

If you are facing out the license expire warning message on your terminal ("*** Warning: This Cache license will expire in 3 days ***") and you do not want that message to be displayed, you can disable/enable that by rinning the following commands:

Do ExpirationMessageOff^%SYS.LICENSE - Disable

Do ExpirationMessageOn^%SYS.LICENSE - Enable

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NewBie's Corner Session: 5 Operator Precedence

Welcome to NewBie's Corner, a weekly or biweekly post covering basic Caché Material.

Click on the Caché Cube in your system tray and select Terminal to try out the commands.

Order Precedence means the order in which mathematical operators are executed. In a Mathematical expression, you may have Multiplication, Addition, Subtraction, and Division. Which of these are executed first, second, third, etc.?

The basic Operator Precedence of mathematics is:

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Hello again and welcome to the next tutorial on this series: Part 4 - Sharing data across router methods. Here we are going to learn how to share a object containing data that is available for read across every router methods.

You're required to complete at least the Part 1 before entering this one. Still, this is supposed to be a really short tutorial, since there isn't much to be said about data sharing.

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First-class functionwiki

In computer science, a programming language is said to have first-class functions if it treats functions as first-class citizens. This means the language supports passing functions as arguments to other functions, returning them as the values from other functions, and assigning them to variables or storing them in data structures. Some programming language theorists require support for anonymous functions (function literals) as well. In languages with first-class functions, the names of functions do not have any special status; they are treated like ordinary variables with a function type.

This post continues the article “Declarative development in Caché”.

[2, 3, 5, 7, 11, 13, 17].forEach(function(i) {
  console.log(i);
});

How to do something like this in Caché using COS?

Below are some exercises on this topic.

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Article
· Jul 7, 2017 19m read
Indexing of non-atomic attributes

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 <...>".

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The attached file contains an example of code generation using ObjectGenerators which builds a very simple homemade RuleEngine.

Code generation is an excellent way of increasing performance moving run-time calculations to compile-time.

We could generate code creating routines or implemeting methods using ObjectGenerators. In this example we are using ObjectGenerators.

Update: Rule Engine is now on GitHub https://github.com/intersystems-ib/cache-iat-ruleengine

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Headache-free stored objects: a simple example of working with InterSystems Caché objects in ObjectScript and Python

Neuschwanstein Castle

Tabular data storages based on what is formally known as the relational data model will be celebrating their 50th anniversary in June 2020. Here is an official document – that very famous article. Many thanks for it to Doctor Edgar Frank Codd. By the way, the relational data model is on the list of the most important global innovations of the past 100 years published by Forbes.

On the other hand, oddly enough, Codd viewed relational databases and SQL as a distorted implementation of his theory. For general guidance, he created 12 rules that any relational database management system must comply with (there are actually 13 rules). Honestly speaking, there is zero DBMS's on the market that observes at least Rule 0. Therefore, no one can call their DBMS 100% relational :) If you know any exceptions, please let me know.

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Many mobile applications that enable users to get information about road fines and pay them, send notifications about newly added fines. This functionality can be efficiently implemented using push notifications sent to users’ devices.

Our application was not an exception. The server side is based on the Ensemble platform that offers integrated support of push notifications starting from version 2015.1.

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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")
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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:

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Article
· Mar 31, 2019 20m read
How to write the home address right?

How Tax Service, OpenStreetMap, and InterSystems IRIS
could help developers get clean addresses

Pieter Brueghel the Younger, Paying the Tax (The Tax Collector), 1640

In my previous article, we just skimmed the surface of objects. Let's continue our reconnaissance. Today's topic is a tough one. It's not quite BIG DATA, but it's still the data not easy to work with: we're talking about fairly large amounts of data. It won't all fit into RAM at once, and some of it won't even fit on the drive (not due to lack of space, but because there's a lot of junk). The name of our subject is FIAS DB: the Federal Information Address System database - the databases of addresses in Russia. The archive is 5.5 GB. And it's a compressed XML file. After extraction, it will be a full 53 GB (set aside 110 GB for extraction). And when you start to parse and convert it, that 110 GB won't be enough. There won't be enough RAM either.

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