Beginning in Caché 2013.1, InterSystems introduced Outlier Selectivity to improve query plan selection involving fields with one atypical value.

In this article, I hope to use an example 'Projects' table to demonstrate what Outlier Selectivity is, how it helps SQL performance and a few considerations for writing queries.

Selectivity

First, let's take a quick look at Selectivity. Selectivity is meta information about the values in one column in a table.

I've asked a lot of questions leading up to this, so I wanted to share some of my progress.

The blue line represents the number of messages processed.  The background color represents the average response time.  You can see ticks for each hour (and bigger ticks for each day).   Hovering over any point in the graph will show you the numbers for that period in time.

This is super useful for "at a glance" performance monitoring as well as establishing patterns in our utilization.

Here is the query used:

SELECT
    mh.name                                  AS MessageType,
    COUNT(mh.

This post is the direct result of working with an InterSystems customer who came to me with the following problem:

SELECT COUNT(*) FROM MyCustomTable

Takes 0.005 seconds, total 2300 rows.  However:

SELECT * FROM MyCustomTable

Took minutes.  The reason for this is subtle and interesting enough for me to write a post about.  This post is lengthy, but if you scroll to the bottom I'll write a quick summary, so if you've gotten this far and think you've already read enough, scroll to the end to get the main point.  Check for the sentence in bold.

Hi All,

            I have a general query in regards to developers experience on extracting data from cache databases and the most efficient way to do so. I work with a number of clients who have applications with cache databases and require the data off the host system and onto data warehouse platforms for research and analysis. Often they require the data in source state which means the extracts are often simply a table scan of the entire database table without any aggregation or manipulation.

This tells me that there is no timezone offset on this table/field:

So why is TimeCreated in this resultset 4 hours less than OneMinuteAgo when I'm clearly requesting only records with a TimeCreated greater than OneMinuteAgo?

I have a list of about 100 MPI IDs that I would like to run a report on.  I want to list times that any data for these patients were accessed.  Currently in "Managed Reports" we have a "Disclosure Report" which I think was a custom development effort, but it is per-patient.

I have a SQL query for the ATNA log but I'm not confident in its accuracy, so I thought I'd reach out and see how other Information Exchange's might get this data.

Hello,

I need to create a query that return the amount of heath related information from a patient. 

I created one using the Analitics but, once our Analitcs database is update once a day this information is not reliable during the current query day.

Part of my Analitcs query is shown below. Where can I find the equivalent tables in Health Share? Any help is appreciate.

Tanks In Advance.

--Analitcs Query

SELECT patient FROM  HSAA.AdvanceDirective union all
SELECT patient FROM  HSAA.Allergy union all
SELECT patient FROM  HSAA.Appointment union all
SELECT patient FROM  HSAA.

I experience this constantly with Cache SQL.  Especially when querying the ATNA log.

SELECT TOP 400000 * FROM HS_IHE_ATNA_Repository.Aggregation ORDER BY ID DESC

That took 12 seconds.  I then upped the number to 500,000 and it took 185 seconds.

Shouldn't the execution time scale proportionately?

If I run the 500,00 query again it takes 2.4 seconds.

I have to connect to an external database and I'd like to use the JDBC SQL Gateway.

I followed this tutorial [1] to create a JDBC SQL Gateway and after configured it works as expected, but I don't know

how use this connection into source code. Maybe these other tutorial is related [2] and [3].

[1] http://docs.intersystems.com/latest/csp/docbook/DocBook.UI.Page.cls?KEY…

[2] https://community.intersystems.com/product-documentation/intersystems-p…

[3] http://docs.intersystems.com/latest/csp/documatic/%25CSP.

I have a class with a string property with DISPLAYLIST and VALUELIST parameters specified.

When I query this class via ODBC I receive logical value as it is and not a display value.

Is there any way (without stored procedure) to get display value?

I need to do an UPDATE via SQL and I would like the statement to return the `ID` column of each row that is updated.  MS SQL has an "OUTPUT" statement, but I don't see anything similar in Cache.  Is there a way to do this?

I have setup an async reporting mirror member with Read only access.  My problem is that if I try to do any sql reporting against that data I am getting errors.  I am sure that this is because the DB is read only, but I had assumed that setting up a reporting mirror would handle this.

I there a setting or mapping  I am missing?

I have been using the query below and it was working fine but now it's giving a SQL error. There were no changes made that could cause this to stop working. There is no Field 'APPLICATIONID' in the table.

QueueSQL=select distinct (convert(char(5),SkillsetID)+'='+Skillset) from iagentbySkillsetStat where ApplicationID > 10000
QueueMappingSQL=SELECT DISTINCT (convert(char(5),SkillsetID)+'='+Skillset), SkillsetID FROM iagentbySkillsetStat iagentbySkillsetStat WHERE (iagentbySkillsetStat.ApplicationID>10000)

DB- Intersystems Cache

Error details for the log files are below.

14/09/2016 11:20:05 a.m.

Hello Fellow Cache Developers:  

Has anyone ever created an index on values of a list property?   If so, would you be willing to share an example?

Also, feel free to offer input and suggestions regarding use of indexes on List values.

I try it with the COLLATE instruction, but doesn't work.

Any ideas ?

Tkanks.

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!*

I have a NewBie Question.

I have been playing around with "Basic CLass Queries."

I  have defined a very simple "Basic Class Query." (see below)

However, I cannot find in the I/S documentation how to execute this query.

Any help is appreciated.

Class LastName.BasicClassQuery Extends LastName.Person
{
Query Display() As %SQLQuery (ROWSPEC="ID:%Integer,Name:%String", CONTAINID = 1)
{
SELECT %ID, Name FROM LastName.Person
 ORDER BY DOB
}
Storage Default
{
<Type>%Library.CacheStorage</Type>
}
}

We are creating a package (written in Caché Object Script) that will provide access to an external DB (MySQL). Because applications that use our package will be run from machines with various, potentially unexpected, operating systems, we’d like to establish a connection to the external DB without using DSNs (we’ve heard that setting up DSNs on certain non-Windows machines can be cumbersome and problematic).

Does anyone know of  way to create a connection to an external DB without using a DSN?

I want to override the Get and Set methods of a class property.  The class maps to a pre-existing global. The property is defined like so:

Property Invalid As %Library.Boolean;

with the property mapping to a node like ^GLOBAL(Code,"INVALID")=1
Code is a property in the same class.

The value can be 0 or 1 or the node might not exist. When it doesn't exist I want the value of the SQL field to come out as 0 (false).

i'm looking for a way to display a list of tables in an application.  I need a Table or Schema API, and I can't find one.  I found this:

http://docs.intersystems.com/latest/csp/docbook/%25CSP.Documatic.cls?PA…

with a google search, but I'm not sure if I can even use this (it says that SQL name is "TABLES"), or how to use it.

Is there a way to get at the table names available in a namespace?

Thanks,

Laura

I want to query the cache database for messages where a specific HL7 segment equals a specific value. Does Cache have a pipe to XML or hl7 segment query function?

Customer is experimenting with %vid variable for selecting row numbering for sql queries. Basically he's trying to implement paging functionality.

He is confused that select %vid from (select ...) returns dummy number whilst select *,%vid from (select...) returns correct data.

I believe, according to the documentation...

The phrase “SELECT * ...” does not include %vid; it must be selected explicitly: “SELECT *, %vid ...”. Also, while this feature is very convenient, especially for porting Oracle queries (this maps

Hi!
There is interesting question in Stackoverflow.
This query works for MS SQL:

SELECT * 
FROM 
(
    SELECT *, ROW_NUMBER() OVER (PARTITION BY client_id ORDER BY date_updated DESC) AS rn
    FROM client_address
) a
WHERE a.rn = 1

There is one answer there,  which solves the task:

SELECT *
FROM 
   client_address a
   LEFT JOIN client_address b
   on a.client_id  = b.client_id 
     and a.date_updated < b.date_updated 
WHERE
   b.client_id is null

But it goes with comment, that there are no Window functions in Caché SQL.

I wonder, are there any other options to make this query in Caché?

Hi,

I'm trying to perform a SELECT with parameters using the EnsLib.SQL.OutboundAdapter. The SELECT returns results but seems to discard the parameters I try to send. I have tried two methods.

First:

Set par(1) = "20160630"
Set par(1,"SqlType") = 12
Set sql = "SELECT Cod, Ing, score FROM [bbdd].[dbo].[vw_Test] WHERE MyParam >= '?'"
Set tSC = ..Adapter.ExecuteQueryParmArray(.QueryResultSet,sql,.par)

Second:

Set par(1) = "20160630"
Set par(1,"SqlType") = 12
Set sql = "SELECT Cod, Ing, score FROM [bbdd].[dbo].[vw_Test] WHERE MyParam >= '?'"
Set tSC = .Adapter.

Hi, after installed Healthshare 2015.2, all the tables previously correctly listed working with Healtshare 2014.1 are NOT listed anymore. TrakCare tables are not listed in the catalogue, nor by the WinSQL Intellisense.

Does anybody know a trick or have a hint to resume this useful functionality back?  

Thanks.

Earlier in this series, we've presented four different demo applications for iKnow, illustrating how its unique bottom-up approach allows users to explore the concepts and context of their unstructured data and then leverage these insights to implement real-world use cases. We started small and simple with core exploration through the Knowledge Portal, then organized our records according to content with the Set Analysis Demo, organized our domain knowledge using the Dictionary Builder Demo and finally build complex rules to extract nontrivial patterns from text with the Rules Builder Demo.

This time, we'll dive into a different area of the iKnow feature set: iFind. Where iKnow's core APIs are all about exploration and leveraging those results programmatically in applications and analytics, iFind is focused specifically on search scenarios in a pure SQL context. We'll be presenting a simple search portal implemented in Zen that showcases iFind's main features.

I have a MySQL server with "posts" table.

I also have a Caché server with "downloadedposts" table. 

They are connected from Caché to MySQL via SQL Gateway

I want to keep Caché table synced with MySQL one  (MySQL "posts" table is a master copy), so periodically Caché queries MySQL server and downloads data. So far so good, and if a record appears or changes in MySQL table, Caché downloads the changes.

The problem I'm encountering is that sometimes rows would be deleted from  MySQL "posts" table.

How do I synchronize deletions?

Recently I have been posting some updates to our JSON capabilities and I am very glad that so many of you provided feedback. Today I would like to focus on another facet: Producing JSON with a SQL query.

Hi -

I'm trying to rewind a cursor back to the first row after looping part of the way through the implied result set, but I'm not finding a way to make this happen, is there some such iterator variable or directive that I can leverage to accomplish this?

I could code around it by pulling identifiers and/or values into a local array, and then hand code up an iterator over my local results copy, but this feels like a "redesigning of a wheel" approach, and I thought I would check before I start down this path.

Thanks

Introduction

The field test of Caché 2016.2 has been available for quite some time and I would like to focus on one of the substantial features that is new in this version: the document data model. This model is a natural addition to the multiple ways we support for handling data including Objects, Tables and Multidimensional arrays. It makes the platform more flexible and suitable for even more use cases.