Relational Tables

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I know that 1-1 relationships are not officialy supported by intersystems cache/iris so I want to know the best way to store data with this kind of data model.

Currently I have two classes that where implemented some time ago:

Table A with a relationship type one on table B

Table B with a relationship type one on table A

To compile I have a double compile with qualifyer U.

What is the best way to implement a data model with 1-1 relationships?

Thank you

 

Last reply 11 days ago
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A More Industrial-Looking Global Storage Scheme

In the first article in this series, we looked at the entity–attribute–value (EAV) model in relational databases, and took a look at the pros and cons of storing those entities, attributes and values in tables. We learned that, despite the benefits of this approach in terms of flexibility, there are some real disadvantages, in particular a basic mismatch between the logical structure of the data and its physical storage, which causes various difficulties.

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Introduction

In the first article in this series, we’ll take a look at the entity–attribute–value (EAV) model in relational databases to see how it’s used and what it’s good for. Then we'll compare the EAV model concepts to globals.

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The typical WHERE condition in SQL relates mostly to some content of the rows you work on.
So it needs to be calculated and checked for each row you access.
Differently (and that's why I named it STATIC) is a WHERE condition that is independent of the rows you access.

Last reply 27 April 2020
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When I describe InterSystems IRIS to more technically-minded people, I always start with how it is a multimodel DBMS at its core.

In my opinion that is its main advantage (on the DBMS side). And the data is stored only once. You just choose the access API you want to use.

Last reply 24 April 2020
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Is there a way to query the database structure?  In SSMS there are queries for finding tables with a column with a certain name (using LIKE).  And there is the redgate tool SQL Search.  But I'm not sure how to go about looking for columns that have say a value of 'PATID' and returning all tables that match.  Does anyone know?

Last reply 15 March 2020
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In Episode 4 of Data Points, we welcome @Benjamin De Boe to the pod to discuss some of the things you can do to optimize your SQL queries in InterSystems IRIS. We've all heard — either from ourselves or from others — the "this runs too slowly" complaint. I thought Benjamin did a great job walking through many of the things within IRIS you can look at with your queries to see what can be improved.

100%/160

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In the previous parts (1, 2) we talked about globals as trees. In this article, we will look at them as sparse arrays.

A sparse array - is a type of array where most values assume an identical value.

In practice, you will often see sparse arrays so huge that there is no point in occupying memory with identical elements. Therefore, it makes sense to organize sparse arrays in such a way that memory is not wasted on storing duplicate values.

In some programming languages, sparse arrays are part of the language - for example, in J, MATLAB. In other languages, there are special libraries that let you use them. For C++, those would be Eigen and the like.

Globals are good candidates for implementing sparse arrays for the following reasons:

Last reply 23 May 2019
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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 reply 31 July 2017
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Greetings,

I am working on the first of many triggers which will have identical code upon row insertion or update of a single column.  According to the document I should be able to define a multiple-event trigger using Cache SQL/DDL.

Here is a link to the current CREATE TRIGGER documentation.  Within the description section is the following paragraph:

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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 reply 8 July 2017
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I have a persistent class where I am logging each CCDA I receive. I want to store all of the providers associated to that CCDA (many to one). In a relational database, I would have a child table with a foreign key to the primary table. I'm guessing the equivalent to Cache would be 

1. Create a custom class (ProviderList) with the properties I want to store.

2. Add the class as a property of my CCDA persistent class.

Property Providers as Array of ProviderList (SQLProjection = "table/column";

Am I on the right track?

Last reply 17 October 2016
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