In my earlier article on Adopting Bitmaps I described the technique already.
Now you can find a code example also on Open Exchange.

A good writer is supposed to draw you in with the title and bury the answer somewhere in the article.  I suppose this makes me a bad writer – don’t think less of me, my whole feeling of self-worth comes from the opinions of internet strangers! 

The Art of Mapping Globals to Classes 1 of 3

Looking to breathe new life into an old MUMPS application?  Follow these steps to map your existing globals to classes and expose all that beautiful data to Objects and SQL.

By following the simple steps in this article and the next two you will be able to map all but the craziest globals to Caché classes.  For the crazy ones I will put up a zip file of different mappings I have collected over the years.  This is NOT for new data; if you don’t already have existing global please just use the default storage.

If you still can’t make heads or tails of your globals, send some example data to Support@InterSystems.com and we will be happy to help you figure it out.

Steps for mapping a global to a class

As we all know, Caché is a great database that accomplishes lots of tasks within itself. However, what do you do when you need to access an external database? One way is to use the Caché SQL Gateway via JDBC. In this article, my goal is to answer the following questions to help you familiarize yourself with the technology and debug some common problems

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)

The Art of Mapping Globals to Classes (2 of 3)

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

This is a sample Ensemble/Health Connect production which demonstrates how to receive an HL7 order (ORM) inbound from a file, extract fields (in this case, basic demographic information), and insert those into a table in an external SQL database via ODBC.  

Included in the zip file:

• Exported code
• Sample ORM message
• 'How to configure' doc 

No doubt bitmap indexing, if used with a suitable property, performs just impressive!
But there is a major limit: ID key has to be a positive integer.
For modern class definitions working with CacheStorage this is a default.

BUT: There are hundreds (thousands ?) old applications out in the field that
are still using composite ID keys.
Or - to name the origin - work on Globals with 2 subscript levels (or more).
They are by construction excluded from our "Bitmap Wonderland".

Of course, using the feature of multiple storage maps could possibly allow to escape - somehow.
But in those cases where you have many many GB of data stored in that way and
where you work with millions of lines of old  - often poorly documented - code.
You wouldn't think seriously more than 5 min. if you change the storage structure or not.
So the bitmap is not with you

As you will know the size of a Global reference is limited to 511 encoded characters. see docs:
http://docs.intersystems.com/latest/csp/docbook/DocBook.UI.Page.cls?KEY=GGBL_structure#GGBL_structure_maxsubscrlen

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The newer dynamic SQL classes (%SQL.Statement and %StatementResult) perform better than %ResultSet, but I did not adopt them for some time because I had learned how to use %ResultSet. Finally, I made a cheat sheet, which I find useful when writing new code or rewriting old code. I thought other people might find it useful.

First, here is a somewhat more verbose adaptation of my cheat sheet

Sometimes, it comes in very handy (especially for the EAV model) to use array properties in a class and be able to qickly search by their elements: both the key and the value.

Let’s take a look at a simple example:

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

Someone posted a question on DC asking whether it was possible to determine access rights for a particular table row always at runtime, and if it was, how could one do that?
Answer: it is possible and it’s not hard at all.

The Art of Mapping Globals to Classes  (2 of 3)

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.

This example is going to cram in 4 or 5 different things beyond what was covered in Part 1 

All that is left after this is the Parent Child mapping example and then you will be on your way.

Same disclaimer:  If you can’t make heads or tails of your globals after reviewing these articles please contact the WRC and we will try to help you out:  Support@InterSystems.com

Steps for Mapping a Global to a Class

Overview

Encryption of sensitive data becomes more and more important for applications. For example patient names, SSN, address-data or credit card-numbers etc..

Cache supports different flavors of encryption. Block-level database encryption and data-element encryption. The block-level database encryption protects an entire database.  The decryption/encryption is done when a block is written/read to or from the database and has very little impact on the performance.

With data-element encryption only certain data-fields are encrypted.  Fields that contain sensitive data like patient data or credit-card numbers. Data-element encryption is also useful if a re-encryption is required periodically. With data-element encryption it is the responsibility of the application to encrypt/decrypt the data.

Both encryption methods leverage the managed key encryption infrastructure of Caché.

The following article describes a sample use-case where data-element encryption is used to encrypt person data.  

But what if you have hundreds of thousands of records with an encrypted datafield and you have the need to search that field? Decryption of the field-values prior to the search is not an option. What about indices?

This article describes a possible solution and develops step-by-step a small example how you can use SQL and indices to search encrypted fields. 

So I know it's been a while, and I hate to let my adoring fans down... just not enough to actually start writing again.  But the wait is over and I'm back!  Now bask in my beautiful ginger words!

For this series, I am going to look at some common problems we see in the WRC and discuss some common solutions.  Of course, even if you find a solution here, you are always welcome to call in and expression you gratitude, or just hear my voice!

This week's common problem: "My query returns no data."

Now, supposedly you've checked that your query SHOULD return data.  That is, if you do a "SELECT * FROM MyTable" and don't get back any data, I don't expect that your more complicated query with JOINs, a WHERE clause, and a GROUP BY will either.  So, if you've determined that the data lives in your table what else could be going wrong?

1) You're in the wrong namespace.