charts v/s tables query

[shrikant.dhomane]

Hi Friends,

I have another problem, this is with respect to charts v/s tables.
I have a simple single area chart that displays in 7 sec ( maximum hotspot set to Zero).
whereas the table(list) appears in 3 sec.

Why is this? can anyone suggest, why for the same data we see delay in chart as compared to table?
Is there anyway to improve the performance of the charts?

Thanks in advance.

Shrikant

[charon]

hi shrikant,

charts are a vizualisation interpreted by your browser. therefore, it might be the rendering that causes that (very small) delay.
In generall, the query of a crosstab or list does not differ from a query of a chart.
in case of a crosstab cognos generates some kind of mdx/ virt. cube in the background, but the query itself will remain i think.

regards

[shrikant.dhomane]

Hi Charon,

Thanks for your reply.

The problem here is we have a report with 12 charts in it. It takes nearly 2mins 30 seconds to run, whereas if I convert them to list tables, it takes only 30 seconds to generate the report.

Customer / user will not be happy with such delay. Wanted to understand why charts takes so long to load the data, as they use the same sql query behind the scene which is used to generate the list tables too.

Any inputs will be very helpful.

Many Thanks,
Shrikant

[kc9400]

Morning,

Do you have the report doing any filtering via prompts? This could be one way to reduce the ammount of time it takes to display each chart.

Might be worth giving it a try and see if you get a performance increase and maybe suggest it to your client and see what they think.

[ykud]

Lists and charts utilise different engines in background, try using cross-tabs, they're rendered similarly to charts.
Crosstabs sometimes cause unwanted local processing, double check that ut's not the cause in your case.


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[CognosPaul]

Crosstabs almost invariably require local processing as most database engines aren't equipped to cleanly pivot data the way authors require. Additionally, the act of creating a large crosstab will generate more cells than a list. Nested, especially more than 6 levels, crosstabs will be increasingly slow. Another slowdown reason is that crosstabs will need to have the query processed completely before rendering while a list will work with a cursor allowing it to render the first page as soon as it receives the data

Generally a pure DMR model on the DQM will have significantly faster performance as Cognos is able to use better caching techniques.

A quick note, OLAP sources will experience slowdowns when using a list for a similar reason. Just as a relational source needs to be pivoted to fit a crosstab, OLAP needs to be unpivoted to fit a list.