Hey Community,

Enjoy the new video on InterSystems Developers YouTube:

A better way of buidling index for IRIS

https://www.youtube.com/embed/Ly-1hukmh8Y
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Hi all,

I'm working on a requirement to loop through all encounter streamlets(SDA) to identify specific encounters based on an encounter extension property for a patient fetch request. However, this current process is time-consuming, and we need to create indexes for that property to quickly retrieve the expected results without going through all the encounter streamlets of a patient.

I would appreciate help on how to achieve this, as I couldn't find any documentation explaining how to create indexes on a SDA element.

Thanks in advance.

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We recently changed the 'UserID" property in a "User" class from type of %String to be %Library.Username. This is for better consistency across our codebase regarding MAXLEN limit.

%Library.Username is a system wrapper datatype which extends %String and has a MAXLEN of 160. This change should have minimal/no impact on code behavior. However, we found that some SQL query cannot return expected rows after the change. Query will return empty values even if the entry is in the table.

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High-Performance Message Searching in Health Connect

The Problem

Have you ever tried to do a search in Message Viewer on a busy interface and had the query time out? This can become quite a problem as the amount of data increases. For context, the instance of Health Connect I am working with does roughly 155 million Message Headers per day with 21 day message retention. To try and help with search performance, we extended the built-in SearchTable with commonly used fields in hopes that indexing these fields would result in faster query times. Despite this, we still couldn't get some of these queries to finish at all.

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Hello everyone,

My team is currently developing guidance and best practices for the generation, storage, and deployment of TUNE TABLE statistics across development and production environments. With that in mind, we want to get an idea of what methods teams in the field have developed for handling this data. In particular, we’d like to know the following:

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Article
· Jul 8, 2023 2m read
Character-Slice Index

A recent question from @Vivian Lee reminded me of a rather ancient example.
It was the time when DeepSee's first version was released.
We got Bitmap Index.
And we got BitSlice Index: mapping a numeric value by its binary parts.
So my idea: Why not indexing strings by their characters?
The result of this idea was presented first in June 2008.
IKnow wasn't publicly available at that time.

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Suppose you have an application that allows users to write posts and comment on them. (Wait... that sounds familiar...)

For a given user, you want to be able to list all of the published posts with which that user has interacted - that is, either authored or commented on. How do you make this as fast as possible?

Here's what our %Persistent class definitions might look like as a starting point (storage definitions are important, but omitted for brevity):

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Hello IRIS Community,

InterSystems Certification is developing a certification exam for InterSystems IRIS SQL specialists, and if you match the exam candidate description given below, we would like you to beta test the exam. The exam will be available for beta testing on June 9 - 12, 2024 at InterSystems Global Summit 2024, but only for Summit registrants (visit this page to learn more about Certification at GS24). Beta testing will open for all other interested beta testers on June 24, 2024. However, interested beta testers should sign up now by emailing certification@intersystems.com (please let us know if you will be beta testing at Global Summit or in our online proctored environment). The beta testing must be completed by August 2, 2024.

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InterSystems FAQ rubric

For volatile tables (tables with many INSERTs and DELETEs), storage for bitmap indexes can become inefficient over time.

For example, suppose that there are thousands of data with the following definition, and the operation of bulk deletion with TRUNCATE TABLE after being retained for a certain period of time is repeatedly performed.

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An interesting pattern around unique indices came up recently (in internal discussion re: isc.rest) and I'd like to highlight it for the community.

As a motivating use case: suppose you have a class representing a tree, where each node also has a name, and we want nodes to be unique by name and parent node. We want each root node to have a unique name too. A natural implementation would be:

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Hi!

I'd like to know if there are any issues if an index is inserted into a table without running the %BuildIndices() method.

It's important to note that data inserted before the index is not important for retrieval, so it's not a problem data inserted before the index don't show up in queries.

The reason why I'm asking this is that I'd like to avoid index reconstruction on big tables which I need to inser such index.

I'm using Cache 2018.1.

Thanks,

José

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Article
· Feb 2, 2021 12m read
A custom SQL index with Python features

Image search like Google's is a nice feature that wonder me - as almost anything related to image processing.

A few months ago, InterSystems released a preview for Python Embedded. As Python has a lot of libs for deal with image processing, I decided to start my own attemptive to play with a sort of image search - a much more modest version in deed :-)

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I'm using Cache SQL and want the ability to choose a specific index.

I've boiled the problem down to one table and simplified the query down to

SELECT *
FROM Registration.PatResp
WHERE SchedApptNum=8450022

SchedApptNum is indexed, but instead of using that column, "Show Plan" indicates that it's looping through the entire Registration.PatResp table on Id (the primary key for the table).

I've done a tune-table with no change.

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Question
· Dec 26, 2019
Performant index on date field

Is there a way to get a good performing index on a date field? I have tried various date property indexes and the query plan is always in a pretty high range. Below are query plan result values I have observed:

StartDate > '2019-12-01' --cost = 699168
StartDate = '2019-12-21' --cost 70666
StartDate between '2019-12-21' and '2019-21-28' --cost = 492058

The query plans above were for type %TimeStamp.

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Our team is reworking an application to use REST services that use the same database as our current ZEN application. One of the new REST endpoints uses a query that ran very slowly when first implemented. After some analysis, we found that an index on one of the fields in the table greatly improved performance (a query that took 35 seconds was now taking a fraction of a second).

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Hello, community!

I've stumbled on some unexpected behavior, and decided to check with you if this is normal. Basically, I'm rebuilding indices and the result is not journaling (which leads to missing indices at shadow server).

The $ZV is "Cache for UNIX (Red Hat Enterprise Linux for x86-64) 2015.2.1 (Build 705U) Mon Aug 31 2015 16:53:38 EDT"

I have an example class

Class tmp.A As %Persistent;

Index IP1 On P1;

Property P1 As %String;

for example there is one object which have P1 = 1, so

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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:

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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.

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Question
· Mar 29, 2019
Ensemble as a Data lake

We have been storing raw messages in a MySQL database for DR and ad hoc purposes. We are thinking of using an Ensemble instance as our data lake instead. We could segregate the source data by namespace or by global. But either way we'll want a custom global to index the data for data retrieval performance purposes.

Anyone else taking this approach? Any feedback?

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