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Performance Issues with many Columns, MongoDB source

Hello dear Denodo team, I have a question regarding the performance of a view based on a MongoDB data source. The base view in question has about 2.7 million records and 256 columns. Running the query ``` SELECT max(date) FROM <table>; ```on base view level results in a runtime of about 10 seconds. On integration view level the same query takes 70 seconds, on business view level more than 2 minutes. The views only use the data from a single MongoDB table. There are no JOINs, only a few string operations. I tried several things and consulted a few of the official Denodo articles on optimization. 1. An index was created in MongoDB as well as in Denodo, but did not lead to any improvement. 2. There are few operations on integration views, that dont seem to matter as there is only a few seconds improvement when taking them out. 3. To utilize the Optimizer I already tried setting up PKs and enabling all the optimizations. 4. Enabling View Statistics for the date field barely yielded a 2 second improvement. We cannot really reduce the column count and a cache is not wanted in this scenario. Is this performance degradation caused by the sheer size of the table or are there possibilities to improve the performance by further settings? Best thanks Update: looking at the execution trace it seems the integration layer and business layer take the to most time. While the base view has an effective time of 456ms, the two following layers (projection) have an ET of >52000 ms. Then there is another group by plan at the end which takes 474ms. Are there some settings we did not try? The problem seems to be with the two top most layers..
user
23-05-2022 12:31:04 -0400

3 Answers

Hello, From the description it is hard to find what is causing the issue. I have seen something quite similar to this in another community question. I would recommend having a look at it through this [link](https://community.denodo.com/answers/question/details?questionId=9064u000000wkIMAAY). If you still find further issues after reviewing that link and you have a valid support user, you can open a support case and ask for further help, as someone will be better able to assist you. Hope this helps!
Denodo Team
24-05-2022 05:38:43 -0400
This is actually a follow-up question to the one you linked :) The provided documents sadly didn't help in finding a solution. Where do I open up a support case?
user
24-05-2022 05:44:03 -0400
Hello, To better help you the best solution would then be for you to create a support case. For that, you can access the [Denodo Support Site](https://support.denodo.com/). This would be the best way to find answers as you can provide execution traces that can be analyzed to detect if there are any issues, for instance. Just bear in mind that you have to be a Denodo Customer and have a Denodo Support User to request this kind of support from the Denodo Support Team. Hope this helps!
Denodo Team
24-05-2022 09:30:52 -0400
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