Great article, Mark!

I have a few notes and questions:

1. Here's a brief comparison of different storage categories:

• Intel® Optane™ DC Persistent Memory has read throughput of 6.8 GB/s and write throughput 1.85 GB/s (source).
• Intel® Optane™ SSD has read throughput of 2.5 GB/s and write throughputof 2.2 GB/s at (source).
• Modern DDR4 RAM has read throughput of ~25 GB/s.

While I certainly see the appeal of DC Persistent Memory if we need more memory than RAM can provide, is it useful on smaller scale? Say I have a few hundred gigabytes of indices I need to keep in global buffer and be able to read-access fast. Would plain DDR4 RAM be better? Costs seem comparable and read throughputof 25 Gb/s seems considerably better.

2. What RAM was used in a Server #1 configuration?

3. Why are there different CPUs between servers?

4. Workload link does not work.

Why do you want to do that?

Use byte[] to pass streams. So:

byte[] bytes = Encoding.Default.GetBytes(txt);
...
var parameter = new object[]
        {
            bytes,
            qspec,  
            errorlog,
            loadedItems
        };

Working with collection properties documentation.

If you want to hold a list of objects at runtume, use %ListOfObjects.

If you want to store a list of objects use collection properties (as you use ListOfPatient).

Where's the printer relative to the Ensemble server?

Any exceptions on stack?

import sys, traceback
traceback.format_exception(sys.last_type, sys.last_value, sys.last_traceback)

Can you run SELECT 1 query?

Properties inherited from % classes and properties starting with %% are skipped in DTL.

Multidimensional properties are skipped in DTL.

Found official (but experimental - use at your own risk) way.

Your class should extend Ens.GenericObject and implement %EnumerateProperties method.

Documentation.

Do you want to call %GetComponentByID  of a parent class?

You can do it like this:

set result = ##super(args...)

Documentation.

Sure, you can access it as:

process.AlertGroups

process is a special variable, holding the current instance of the BPL process.

Load method writes to the current device which is a big no in the Native API ecosystem. Add flags to suppress all output:

var qspec = "/displaylog=0 /displayerror=0";  

Supported platforms for Ensemble are listed here, for InterSystems IRIS here.

If you don't want to use RHEL you can choose between:

• Ubuntu 16.04 LTS
• Oracle 7
• SUSE Linux Enterprise Server 12

I prefer Ubuntu.

1 sql request per property, or only one "big" sql request ?

How are you planning on merging distinct requests? One case I've seen where you need something like this is when you want to get a valid subset of filter values (which would return 1+ rows) for each next filter, but in the end all filters are still combined into one query.

You need to decide on:

• what predicates are allowed (=, %STARTSWITH, <, >, LIKE, IN, ISNULL, BETWEEN)
• what logic operations are allowed (OR, AND, NOT)
• are nesting and brackets allowed
• is it free form (auto constructed from metadata) or fixed (from a pre-set list of properties).

After that on a client you construct filter object, validate and parse it on a server and execute the query.

If you're not satisfied with performance, server-side part can be tweaked without modifying the client.

what's the disadvantage of using lot of indexes ?

INSERTS/UPDATES are slower, more space is needed.

Tasks contain session reference so you can simplify your query to:

SELECT
TaskStatus_Request As ID
FROM EnsLib_Workflow.TaskResponse
WHERE TaskStatus_SessionId = ?

For debugging: add hang 1 before executing SQL. What happens?

What do you want to do with ID?