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#Databases

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InterSystems Caché database is a file where all the data, application scripts, and users, roles and security configurations are stored. Typically the name of the file is cache.dat.

Documentation.

Astronomers’ tools

5 years ago, on December 19, 2013, the ESA launched an orbital telescope called Gaia. Learn more about the Gaia mission on the official website of the European Space Agency or in the article by Vitaly Egorov (Billion pixels for a billion stars).

However, few people know what technology the agency chose for storing and processing the data collected by Gaia. Two years before the launch, in 2011, the developers were considering a number of candidates (see “Astrostatistics and Data Mining” by Luis Manuel Sarro, Laurent Eyer, William O’Mullane, Joris De Ridder, pp. 111-112):

Comparing the technologies side-by-side produced the following results (source):

Technology Time
DB2 13min55s
PostgreSQL 8 14min50s
PostgreSQL 9 6min50s
Hadoop 3min37s
Cassandra 3min37s
Caché 2min25s

The first four will probably sound familiar even to schoolchildren. But what is Caché XEP?

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Hello everyone,

Im just wondering if there is any possibility to "Listen" to a cache DB? We have our cache DB somewhere else provided by a different company, we are provided the interface to connect to that cache DB so we can extract the cache DB every night.

Im just curious if theres a way to "listen" to the cache DB, so if theres any changes on the table in the cache DB, I could make a trigger to extract the table again.

I know i could just set my ETL every hour or so... but that would extract all the tables in cache DB.

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Currently, we have an application running in one namespace ("Database B") that has globals and routines mapped to another database ("Database A"). After enforcing clean up on Database A, we found that 90% of the disk is free. We would like to compact Database A and release the unused space. However, we are running OpenVMS, which seems to be the issue.

For databases consisting of only globals, we are able to use ^GBLOCKCOPY; however, we need to ensure that the routines and mappings are also copied.

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I've been accessing Cache tables from a developer/reporting side, but am now involved in a project to create a data warehouse for our application. I'm trying to find a query I can use to return the sizes of all the tables in the database, so we can identify the largest tables and handle those individually. Can someone give me a query I can run against our Cache database to return the sizes of all the tables from largest to smallest?

Thanks for the help

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Hi,

I'd like to compare classes in two namespaces, whether the corresponding .cls code exist in both namespaces or not, and if it does exist in both namespaces, whether the CLS code is identical. If there is such a routine out there the better, I'd like to see it. If not, I know how to get a list of classes in each namespace and I can check currClss.TimeChanged. What I cannot find is the following:

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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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I would like to know if there is a way of having a callback or something similar, on persistent classes that is always called after the execution of the operation (failed or successfull).

%OnOpen is executed prior to the action, and there is no post callback

%OnAfterDelete and %OnAfterSave are executed after a successfull operation

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Hi,

I am getting below error in date column in a table. I am unable to query data or find distinct or to_char on this column.

Select distinct column name from table
Select column name from table
Select To_Char(column name) from table

Table has 3923509 rows.

Could someone help me how can I identify bad data in this table?

Any idea how we can avoid this error?

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I have a CACHE.DAT file that is working under CACHE version 2015.1.0.429.0

I have a second machine with CACHE version 2017.2.0.741.0

When I attempt to add/use the CACHE.DAT in the new version of CACHE, it will not mount.

How do I upgrade/convert the DAT file to make it work under the new CACHE version?

Thx. Larry...

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Question
· Nov 1, 2019
Compaction of Large globals

I would like to Compact globals in a database to free up space.

I would begin the process on Saturday morning, but am concerned, due to the size, that it would not complete by Sunday evening. I understand that the process is setup so that it can run with users on the system, however, as the advice indicates, this would not be ideal.

Can the process be stopped if it does not complete by the time you want/need it to?

Do you know how to guestimate how long the process would take?

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We are trying to come up with huge DataStore which needs to store HIPAA transactions and Data getting partitioned with idkey - YYYYMM. Current Live data get inserted into current Month DB - HIPAA_202306. 10 years (Hipaa retention policy) old data is going to be sitting in to 120 DBs ( 201606_HIPAA, 201607... 202305) for historical audit legal compliance purposes.

Currently if we create Namespace we get 2 databases - CODEDB for routes/classes & DATADB for journals data.

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I need to see the full SMTP trace when a %Net.SMTP attempts to send an email to troubleshoot an issue. As far as I know, the only way to get that is to uncomment line 192 in the %Net.SMTP class.

 //:#define SMTPTRACE

I've done this in the past by giving myself the %DB_IRISSYS role, so I tried that. That database is also not mounted as read-only.

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Article
· Nov 11, 2019 11m read
Transactions in Global InterSystems IRIS

InterSystems IRIS supports a unique data structure, called globals, for information storage. Essentially, globals are persistent arrays with multi-level indices, having several extra capabilities—transactions, quick traversal of tree structures, and a programming language known as ObjectScript.

I'd note that for the remainder of the article, or at least the code samples, we'll assume you have familiarised yourself with the basics of globals:

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I get this on some queries in some namespaces. For instance, this query:

SELECT TOP 10 SessionId, datediff(s,min(TimeCreated),max(TimeCreated)) as ResponseTime
FROM ens.messageheader
GROUP BY SessionId
ORDER BY ResponseTime DESC

It works fine in HSBUS but in HSREG it throws the error.

Server closed communication device

Does anyone know what would cause this? Would it log something more useful somewhere?

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Article
· May 11, 2021 8m read
IRIS in Astronomy

In this article we are going to show the results of the comparision between IRIS and Postgress when handling Astronomy data.

Introduction

Since the earliest days of human civilization we have been fascinated by the sky at night. There are so many stars! Everybody has dreamed about them and fantasized about life in other planets.

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We don't often use SQL within our org, which is mostly due to the performance issue we experience due to the quantity of data we are reviewing.

Aside from the standard performance measures for non-Caché databases, are there any recommended approaches when querying large tables?

The table would have roughly 50M records, but there are not a finite amount of sub-nodes.

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