#SQL

Have some free text fields in your application that you wish you could search efficiently?  Tried using some methods before but found out that they just cannot match the performance needs of your customers?  Do I have one weird trick that will solve all your problems?  Don’t you already know!?  All I do is bring great solutions to your performance pitfalls!

As usual, if you want the TL;DR (too long; didn’t read) version, skip to the end.  Just know you are hurting my feelings.

Date range queries going too slow for you?  SQL Performance got you down?  I have one weird trick that might just help you out! (SQL Developers hate this!)*

If you have a class that records timestamps when the data is added, then that data will be in sequence with your IDKEY values - that is, TimeStamp₁ < TimeStamp₂ if and only if ID₁ < ID₂ for all IDs and TimeStamp values in table - then you can use this knowledge to increase performance for queries against TimeStamp ranges.  Consider the following table:

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".

As you know in Caché / IRIS you have the possibility to define a property as Multidimensional as documented here:
https://docs.intersystems.com/iris20201/csp/docbook/DocBook.UI.Page.cls?KEY=GOBJ_proplit#GOBJ_proplit_multidim
and the explanation of how to use it
https://docs.intersystems.com/iris20201/csp/docbook/Doc.View.cls?KEY=GOBJ_proplit#GOBJ_proplit_multidim_values

Though the access is quite comfortable (in traditional COS sense) there are 2 main restrictions that hurt:

#1) It is not saved to disk unless your application includes code to save it specifically.
#2) It cannot be stored in or exposed through SQL tables
   there are some more
I'll show how to overcome these limits

While the classic solution followed rather close the concepts and design of the ancestors
Caché / IRIS allows a more modern approach to flexible/multidimensional properties

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

This is a coding example working on Caché 2018.1.3 and IRIS 2020.2 
It will not be kept in sync with new versions 
It is also NOT serviced by InterSystems Support !

InterSystems IRIS 2020.1 brings a broad set of improved and new capabilities to help build important applications. In addition to the many significant performance improvements accrued through 2019.1 and 2020.1, we are introducing one of our biggest changes in recent SQL history: the Universal Query Cache. This article provides more context on its impact to SQL-based applications at a technical level.

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

I'm facing a specific sort problem.
There are several thousands of articles sold all over. 
Users expect to get a description in local language sorted by their specific collation.

Similar to Caché so also in IRIS,  you have ClassQueries available in 2 variants

• Basic class queries, which use the class %SQLQuery and an SQL SELECT statement.
• Custom class queries, which use the class %Query and custom logic to execute, fetch, and close the query.

Date range queries going too slow for you?  SQL Performance got you down?  I have ANOTHER weird trick that SQL Developers don't want you to know!*

To request a copy of the examples only – please see me, will email them out for free.  pmkadow@gmail.com

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 

This is a coding example working on Caché 2018.1.3 and IRIS 2020.2 
It will not be kept in sync with new versions 
It is also NOT serviced by InterSystems Support !

Standard error logs in IRIS / Caché / Ensemble are written global ^ERRORS.
As this piece dates back some decades back to previous millennium its structure
is far from the typical SQL storage structures.