Author Topic: Does Cognos apply filters before or after retrieving data?  (Read 414 times)

Offline cognosdelaware

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I had a question about Cognos and filters.

Does Cognos pull back all the data from the database/table and then apply filters to the data OR are the filters applied at a database/table level and the filtered records returned to Cognos?

Thank you

Offline Naveen nani01

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Re: Does Cognos apply filters before or after retrieving data?
« Reply #1 on: 04 Aug 2017 10:57:03 am »
Yeah

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Offline Naveen nani01

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Re: Does Cognos apply filters before or after retrieving data?
« Reply #2 on: 04 Aug 2017 10:58:54 am »
By using aggregations on filters after or before aggregations we will filter the date by using some queries

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Offline MFGF

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Re: Does Cognos apply filters before or after retrieving data?
« Reply #3 on: 04 Aug 2017 11:05:19 am »
I had a question about Cognos and filters.

Does Cognos pull back all the data from the database/table and then apply filters to the data OR are the filters applied at a database/table level and the filtered records returned to Cognos?

Thank you

Hi,

The answer is either of those might happen, depending how you are filtering and how the report is written. In most cases, the query engine can figure out how to take your filters and write a database query to include them, thereby getting the database to apply the filters and return a filtered result set. In some cases this isn't possible, though - for example if you are reporting over multiple data sources and you have a filter comparing a value from one data source with a value from the other. If you're unsure, take a look at the generated SQL (the Native SQL) and you should see if the appropriate predicate(s) is/are included.

Cheers!

MF.
Meep!

Offline cognosdelaware

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Re: Does Cognos apply filters before or after retrieving data?
« Reply #4 on: 04 Aug 2017 11:06:56 am »
My question was, if I have a filter on my data, does the filter get applied at the database level BEFORE the data is returned to Cognos OR does ALL the data come back from the database and then Cognos applys the filters?

Online Lynn

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Re: Does Cognos apply filters before or after retrieving data?
« Reply #5 on: 07 Aug 2017 01:57:51 am »
My question was, if I have a filter on my data, does the filter get applied at the database level BEFORE the data is returned to Cognos OR does ALL the data come back from the database and then Cognos applys the filters?

MFGF answered your question quite clearly I thought. Did you see that response?

Offline Invisi

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Re: Does Cognos apply filters before or after retrieving data?
« Reply #6 on: 17 Aug 2017 04:48:18 am »
Perhaps you mean before or after the aggregation result? This is a parameter you can set for the filter. By default the filter is applied before aggregation, so like a regular where. So if you want to have the filter work on your result (after aggregation), you must change the parameter.
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