Contestant

What is Journaling?

Journaling is a critical IRIS feature and a part of what makes IRIS a reliable database. While journaling is fundamental to IRIS, there are nuances, so I wrote this article to summarize (more briefly than our documentation which has all the details) what you need to know. I realize the irony of saying the 27 minute read is brief.

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InterSystems FAQ rubric

To remove InterSystems products installed on your Windows system, use Add or Remove Programs in Control Panel (in Windows 10, select Apps from Windows Settings).

Since we will be making changes to the system, you will need to log in as a user with administrator privileges.

1) Log in to the system as an administrator.

2) From the system tray, exit the launcher of the InterSystems product instance you want to uninstall (click launcher → exit).

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Article
· Nov 9, 2016 5m read
How the Ensemble Scheduler Works

The Ensemble Scheduler is used for automatically turning on and off business hosts at certain dates and times. You could use it if, for example, you wanted to only run a business host from 9am to 5pm every day. Conversely, if you want do to trigger an event to occurr at a specific time, for example, a job running at 1am to batch up and send off all the previous day's transactions in one file, we recommend other methods such as the Task Manager.

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InterSystems FAQ rubric

If the system does not stop for 24 hours, old journal files will be deleted at 0:30 according to the "Journal file deletion settings".

A possible cause of journal files remaining that are older than the "Journal file deletion settings" is that there are transactions that remain open.

In that case, you will be able to delete the journal file by searching for processes executing transactions and finalizing the transactions.

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The ideal number of table permissions to assign for your users is zero. Permissions should be granted upon sign-in based on the application used for access. For web applications, we have a simple way of doing this by appointing application roles, matching roles, and required resources in the System Management Portal.

ODBC and JDBC connections present a different problem, however, especially when third-party applications are involved. As providers of an ERP system, our customers often wish to be able to employ various software packages to integrate with or report on their data. Many of these programs are capable of running any kind of query. Yet, letting them do that can be devastating to a customer’s data.

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Hi, this post was initially written for Caché. In June 2023, I finally updated it for IRIS. If you are revisiting the post since then, the only real change is substituting Caché for IRIS! I also updated the links for IRIS documentation and fixed a few typos and grammatical errors. Enjoy :)

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[Background]

InterSystems IRIS family has a nice utility ^SystemPerformance (as known as ^pButtons in Caché and Ensemble) which outputs the database performance information into a readable HTML file. When you run ^SystemPerformance on IRIS for Windows, a HTML file is created where both our own performance log mgstat and Windows performance log are included.

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Article
· Jun 30, 2020 3m read
Replicating Audit Log Near Real Time
Many organisations implement centralised log management systems to separate and centralise the log data in order to e.g. automate threat detection (and response) and to comply with regulatory requirements. The primary systems of interest are the various user facing applications, but increasingly also other kinds of systems including integration platforms.
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InterSystems FAQ rubric

There is no need to recompile the routines after the version upgrade, but since the version update overwrites %SYS, user-created INT and OBJ format routines (*.INT,*.OBJ) in %SYS will be deleted. Therefore, you need to be careful.

MAC, INT and OBJ routines with the following names are not deleted.

%Z*.INT, %z*.INT, Z*.INT,z*.INT
%Z*.OBJ, %z*.OBJ, Z*.OBJ,z*.OBJ

Please note that classes/CSPs need to be compiled after upgrading.

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InterSystems FAQ rubric

To resolve the error <PROTECT>, remove the read-only attribute of the system-wide library database (IRISLIB for InterSystems IRIS, CACHELIB for Caché/Ensemble/HealthShare (Caché-based))

Once you have finished importing the routine, remember to change it back to read-only.

[Version 2013.1 and above]
[Management Portal] > [System Administration] > [Configuration] > [System Configuration] > [Local Database] Uncheck "Mount read-only" from the database name link.

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I am often asked by customers, vendors or internal teams to explain CPU capacity planning for large production databases running on VMware vSphere.

In summary there are a few simple best practices to follow for sizing CPU for large production databases:

  • Plan for one vCPU per physical CPU core.
  • Consider NUMA and ideally size VMs to keep CPU and memory local to a NUMA node.
  • Right-size virtual machines. Add vCPUs only when needed.

Generally this leads to a couple of common questions:

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When there's a performance issue, whether for all users on the system or a single process, the shortest path to understanding the root cause is usually to understand what the processes in question are spending their time doing. Are they mostly using CPU to dutifully march through their algorithm (for better or worse); or are they mostly reading database blocks from disk; or mostly waiting for something else, like LOCKs, ECP or database block collisions?

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Article
· Jun 1, 2023 1m read
How to shrink the IRISTemp database

InterSystems FAQ rubric

You can set the maximum size of the IRISTemp database at IRIS startup by setting a configuration parameter called MaxIRISTempSizeAtStart.

After setting, the system will truncate IRISTemp to the set value (MB) at the next IRIS startup. If the current size is less than the specified MaxIRISTempSizeAtStart, no truncation will occur. Also, if 0 is specified, truncation will not be performed, so the size will start without changing. (Default) Settings are made from the menu below.

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Here in %SYS, we have already examined users, resources, and roles. Now that we know how to set all of that up, we should give it a purpose. Next we will talk about applications! As you may expect, we will see various identical class methods defined here that we have seen in the previous classes. However, some of them will have some tiny yet significant differences.

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Article
· Sep 22, 2016 3m read
Windows write caching

(This article was reviewed in February 2021. It is still relevant to Caché-based installations and similarly applies to IRIS-based installations.)

This article discusses the Windows write caching setting which can leave systems vulnerable to data loss or corruption in the event of power loss or operating system crash. The setting is on by default in some Windows configurations.

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InterSystems FAQ rubric

※Use this method if you want to compare databases that have been replicated using mirroring, shadowing, or some other mechanism.

You can use the DATACHECK utility to compare global variables. Please refer to the document below.
Overview of DataCheck [IRIS]

***

Routine comparisons use the system routine %RCMP or the Management Portal.

Below is how to use it in the Management Portal.

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