This is the first in a pair of articles on SQL indices.

Part 1 - Know your indices

Here's a sample code to display JSON or dynamic object.

It shows how to iterate over object, get property values and their paths.

Recently I needed a classmethod that returns annotation value based on a name of a activity.

As doing it at runtime seemed inefficient, I wrote compile-time utility that iterates over all business process activities and generates relevant code.

This code could be used in a variety of situations when you need to iterate over business process activities, just add it as a secondary superclass to your BPL processes.

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.

Howdy, Developer Community!

Here’s a fun little formatting problem you may run into when trying to use the RSAEncrypt method of %SYSTEM.Encryption (also useable as $System.Encryption.RSAEncrypt()!), which is documented here:

There are three things most important to any SQL performance conversation: Indices, TuneTable, and Show Plan. The attached PDFs includes historical presentations on these topics that cover the basics of these 3 things in one place. Our documentation provides more detail on these and other SQL Performance topics in the links below. The eLearning options reinforces several of these topics. In addition, there are several Developer Community articles which touch on SQL performance, and those relevant links are also listed.

There is a fair amount of repetition in the information listed below. The most important aspects of SQL performance to consider are:

1. The types of indices available
2. Using one index type over another
3. The information TuneTable gathers for a table and what it means to the Optimizer
4. How to read a Show Plan to better understand if a query is good or bad

This code snippet sends an XML request to a server and saves the response to a file. The class method "test" runs the code:

Class objectscript.postXML
{
    classmethod test() {
        Set HTTPRequest = ##class(%Net.HttpRequest).%New()
        Set HTTPRequest.ContentType = "text/xml"
        Set HTTPRequest.NoDefaultContentCharset = 1
        Set HTTPRequest.Location = "ITOMCZ"
        Set HTTPRequest.Server = "wph.foactive.com"
        Do HTTPRequest.RemoveHeader("User-Agent")  
        Do HTTPRequest.RemoveHeader("Accept-Encoding") 
        Do HTTPRequest.RemoveHeader("Connection")
        Do HTTPRequest.SetHeader("Expect","100-continue")
     
        Set RequestXML = ##class(%Library.File).%New("c:\test.xml")
        Do RequestXML.Open("RS")
        Do HTTPRequest.EntityBody.CopyFrom(RequestXML)
        Do RequestXML.%Close()
     
        Do HTTPRequest.Post(HTTPRequest.Location)
     
        Do $System.OBJ.Dump(HTTPRequest)
        Do $System.OBJ.Dump(HTTPRequest.HttpResponse)
     
        Write HTTPRequest.HttpResponse.Data.Size
        Write HTTPRequest.ContentLength
     
        Set ResponseStream = ##class(%Stream.FileBinary).%New()
        // Second part is typically the file extension, i.e.: application/pdf -> pdf
        Set FileType = $Piece(HTTPRequest.HttpResponse.GetHeader("CONTENT-TYPE"),"/",2)
        Set ResponseStream.Filename = "C:\test."_FileType
     
        Write ResponseStream.CopyFrom(HTTPRequest.HttpResponse.Data)
     
        Write ResponseStream.%Save()
        Do ResponseStream.%Close()
    }
}

Here's a link to the code on GitHub

Intro

Recently I reread this article by @Bernd Mueller. It's about calling DELFATE function from zlib library. In this article I'll demonstrate several different approaches to callout libraries, we'll build the same functionality (compress function) in several different languages and compare them.

The following code walks a DOM using %XML.Node. It also prevents %XML.Writer to change whitespace. Run the code using the class method "test":

Class objectscript.walkDOM Extends %Persistent
{
    ClassMethod dfs(node As %XML.Node)
    {
        s entrynode=node.NodeId
        do {
        //element nodes with one whitespacetyped child are the ones we want to change
        if (node.NodeType=$$$xmlELEMENTNODE){
            s snode=node.NodeId     
            if (node.MoveToFirstChild())            
                {
                    i ('node.MoveToNextSibling()){
                        i (node.NodeType=$$$xmlWHITESPACENODE){
                            s node.NodeType=$$$xmlTEXTNODE
                            s node.NodeId=snode
                        }
                    }
            }
            s node.NodeId=snode     
        }   
        if (node.HasChildNodes()){
            d node.MoveToFirstChild()
            d ..dfs(node)
        }
        } while (node.NodeType'="" && node.MoveToNextSibling())
        s node.NodeId=entrynode
         
    }
     
    ClassMethod test()
    {
      set xml = "abcdefg"
     
      s reader=##class(%XML.Reader).%New()
      do reader.OpenString(xml)  
      set writer = ##class(%XML.Writer).%New()
      //do some magic
      d ..dfs(reader.Document)
       
      w !,"with indent=1:",!
      set writer.Indent = 1
      do writer.OutputToString()
      do writer.Document(reader.Document)
      w writer.GetXMLString()
      set writer.Indent = 0
      w !,"with indent=0:",!
      do writer.OutputToString()
      do writer.Document(reader.Document)
      w writer.GetXMLString()
    }
}

Here's a link to the code on GitHub: https://github.com/intersystems-community/code-snippets/blob/master/src/...

Easily transform a CSV file into a personalized preview of DeepSee - InterSystems BI

AnalyzeThis can be found on InterSystems Open Exchange. Use the Download link to navigate to GitHub and begin installing the project. Follow the “Installation” section of the GitHub README.

Some weeks ago, I was reading a book by Stephen Hawking and Leonard Mlodinow, The Grand Design. At a certain point, trying to define why do we exist? , why do we use the models we use in physics?, ...those kind of things you know... they pointed at the Game of Life example invented by the mathematician John Coward in 1970... Basically he wanted to show that a system with really basic fundamental laws (Physics) could evolve and "live" to become a more complex system (Chemistry) in which "something" (humans) could work out its own model and complex rules to explain its reality… the rules for this deterministic model that he exposed were so basic that I thought it could be funny to implement them in ObjectScript when I had some spare time... there are others implementations in JavaScript and other languages... but not in ObjectScript... and that had to be corrected!!… so here you are!

There's a new and exciting enhancement to QEWD that has just been released - it's an additional layer of abstraction known as QEWD-Up. QEWD-Up hides away all the mechanics of QEWD itself, allowing you to focus on just your REST APIs and the code that implements them.

Additionally, and importantly, QEWD-Up simplifies the maintenance of your REST APIs, allowing you (and others) to quickly and easily understand their life-cycle and implementation.

Astronomers’ tools

5 years ago, on December 19, 2013, the ESA launched an orbital telescope called Gaia. Learn more about the Gaia mission on the official website of the European Space Agency or in the article by Vitaly Egorov (Billion pixels for a billion stars).

However, few people know what technology the agency chose for storing and processing the data collected by Gaia. Two years before the launch, in 2011, the developers were considering a number of candidates (see “Astrostatistics and Data Mining” by Luis Manuel Sarro, Laurent Eyer, William O’Mullane, Joris De Ridder, pp. 111-112):

• IBM DB2,
• PostgreSQL,
• Apache Hadoop,
• Apache Cassandra and
• InterSystems Caché (to be more precise, the Caché eXTreme Event Persistence technology).

Comparing the technologies side-by-side produced the following results (source):

The first four will probably sound familiar even to schoolchildren. But what is Caché XEP?