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Fetch plan of the query cache

Hello. I work with a cache for views. And faced with strange behavior. When I am disabled the cache for a view, the execution time amounted ~50ms. When I am enabled partial cache, the execution time amounted ~400ms. I need opportunities for fetching plan of using cache, for understanding how and when Denodo uses the cache. What resources exist for this? I work on a licensed server, version 6. Thank you in advance.
user
23-02-2017 09:09:33 -0500
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3 Answers

Hi, To answer your question, when I run a view with Cache mode off, the query hits the data source directly but when I execute a query with Partial cache mode enabled, the Virtual Data Port server first checks if it can retrieve the data from the current cached data depending on the condition and the TTL. If not, it retrieves the data from the data source. Hence there is a difference in execution time. I would recommend you to have a check on below options available under Partial Cache Mode to overcome the above scenario, -Match Exact Queries -Explicit loads You can refer to section “15.2” in "VDP Administration Guide" to know more about how cache works in Denodo and its functionalities. Hope this helps!!
Denodo Team
24-02-2017 08:48:24 -0500
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Thank you for the answer, Before start working with the cache, I read a documentation. But it doesn't describe behavior from the question. Could you please advise tools or commands for fetching plan of the cache for views? Maybe debug mode on server or something like this
user
24-02-2017 09:32:19 -0500
Hi, If I want to view the 'Execution Plan' of the query, I would try any one of the below options, - Using "Execution Trace" , Under 'Query Results' Tab, I use 'Execution Trace' tab to know the 'Execution Plan' of the executed view. - Using "Desc Queryplan <Query to be executed>" I use this option if I need to know what will be the "Execution Plan" of a view before execution. You can execute "DESC QUERYPLAN select * from sample_view" in the VQL shell and use 'Output' tab to view the execution plan. You can refer to section "4.6.1 Execution Trace of a Statement " in Virtual DataPort Admin Guide and section "15 DESCRIBING CATALOG ELEMENTS" in Advanced VQL Guide to know more about Execution trace and Desc Query plan. Hope this helps!!
Denodo Team
01-03-2017 06:59:24 -0500
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