New post

#SQL

13

SQL is a standard language for storing, manipulating and retrieving data in relational databases.

So I know it's been a while, and I hate to let my adoring fans down... just not enough to actually start writing again. But the wait is over and I'm back! Now bask in my beautiful ginger words!

For this series, I am going to look at some common problems we see in the WRC and discuss some common solutions. Of course, even if you find a solution here, you are always welcome to call in and expression you gratitude, or just hear my voice!

This week's common problem: "My query returns no data."

7 1
0 451

When working with a large query executed though an ODBC connection what is the best way to allow the paging of the results at the client side. I have tried some methods using %VID and similar methods, but these really don't seem to work as the value returned is related to the ID of the data and not the position in the results set. What would be ideal is if the value seen in the management portal when you check of "Row Number" was available to external queries through ODBC. I have not seen a way to return this however.

0 5
0 925

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.

0 7
0 967

Hello Fellow Caché Developers,

The purpose of this post is to ask for everyone's thoughts and input around the use of transient, SQLCalculated/Computed properties within persistent classes.

This approach allows for extra data values needed in SQL queries to be available without having to join to other tables.

Very simple/basic example to illustrate the topic:

Let's say I have a persistent class named ICDAutoCodeDefn to hold ICD Auto-Coding definitions, such as:

0 4
0 799
Question
· Feb 12, 2016
Help with SQL error

Error:

[SQLCODE: <-400>:<Fatal error occurred>]
[Cache Error: <<SUBSCRIPT>%0AmEdun+4^%sqlcq.HSREGISTRY.cls966.1 ^||%sql.temp(1,"")>]
[Location: <ServerLoop - Query Fetch>]
[%msg: <Unexpected error occurred: <SUBSCRIPT>%0AmEdun+4^%sqlcq.HSREGISTRY.cls966.1 ^||%sql.temp(1,"")>]

Here is an example of a query that gives the error:

SELECT COUNT(DISTINCT Criteria) as Relevance FROM HS_IHE_ATNA_Repository.Aggregation
WHERE EventType = 'CROSS GATEWAY QUERY'

0 10
0 4.6K

I have a class which defines a property as array of %String. Is it possible to index values of this property and use this property in SQL?

I have tried 'Index idx On prop(ELEMENTS)' and then a select from the generated collection table, but this is still orders of magnitude slower than queries to the containing class.

1 2
0 489

In writing some code on:

Cache for Windows (x86-64) 2015.1 (Build 429U) Fri Feb 13 2015 14:37:23 EST

I noticed an unexpected "ROLLFAIL" error when a Unique Index fail was generated in a %Save() call.

The object SHOULD fail to save, since the Unique criteria is not met, but I didn't expect to see a ROLLFAIL error as the "Last Error".

When running the following class code:

0 4
0 1K

i have this error

DrawTableError : <MAXSTRING> zDrawTable+349^%CSP.Util.TablePane.2

perhaps i have the possibility of Deleting all history queries, but i think better to check the table where last queries were stored and solve it by deleting wrong registries. anybody knows where is the table 'QueryHistory'.

0 3
0 313

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?

0 7
0 992

Since now i have been working from external connection but i want to work with the SQL utility of Management Portal

i dont know how to do with several instructions like in other editors like this example

update Prod.Articulos set Alto = 1646, Ancho = 16, Fondo =  80 where CodigoNum = '100' and Empresa = 'CO'
update Prod.Articulos set Alto = 1646, Ancho = 16, Fondo =  400 where CodigoNum = '101' and Empresa = 'CO'
update Prod.Articulos set Alto = 1646, Ancho = 16, Fondo =  400 where CodigoNum = '102' and Empresa = 'CO'

it returns

0 11
0 708

Running TuneTable accounts among other the parameter named Block Count. In documentation, we see that this is an approximate numbers of 2K-blocks in which SQL-maps are stored. Databases in recent Cache doesn't support 2K-physical blocks so SQL-blocks are not physical blocks as it seems. So two questions:

- what are these blocks?

- how knowledge about count of blocks can help in SQL optimization?

0 4
0 514
Article
· Nov 8, 2016 4m read
Introduction to Outlier Selectivity

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.

3 1
0 657

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.

5 2
0 513

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.

1 2
0 1.7K

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

Select TOP 1 GETDATE() as Now, TimeCreated FROM ens.messageheader ORDER BY TimeCreated DESC;
Now TimeCreated
------------------- -------------------
2016-10-18 16:16:49 2016-10-18 16:16:31
0 13
0 830

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.

0 7
0 512

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

1 6
0 431

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.

0 4
0 449