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Parameter push-down issue

I am facing an issue when using the parameter in where condition of the top-level views. The query is hierarchical and has five levels. I created a parameter for the top-level view for a key element "key_id" that is used to join several tables. Then, I used this parameter key_id in the where clause of the top-level view as key_id = '1234'. In the second level of the hierarchy, there are four views where the corresponding key id is used in the join of these views. When I checked the delegated queries, it pushed this parameter down to 3 out of 4 views (in where clause) except for one view. Tried to refresh, rename, drop, and recreate this particular view to make sure it is not a refresh issue, but nothing helped. Please suggest how else I could debug and fix this issue.
user
04-02-2020 11:28:48 -0500

2 Answers

Join reordering helped fix the issue.
user
04-02-2020 21:23:55 -0500
Hi, Glad that you got it working. Generally, Denodo Platform Execution Engine performs [Automatic Simplification of Queries](https://community.denodo.com/docs/html/browse/7.0/vdp/administration/optimizing_queries/automatic_simplification_of_queries/automatic_simplification_of_queries#automatic-simplification-of-queries) by applying optimization techniques such as join reordering, branch pruning, etc.. in order to increase the number of operations that are delegated to the source. Hence, in case I want to optimize the queries, I would check if the Automatic simplification of queries option is enabled in the “Administration > Server configuration > [Queries optimization](https://community.denodo.com/docs/html/browse/latest/vdp/administration/server_administration_-_configuring_the_server/queries_optimization/queries_optimization#queries-optimizationhttps://community.denodo.com/docs/html/browse/latest/vdp/administration/server_administration_-_configuring_the_server/queries_optimization/queries_optimization#queries-optimization)” menu of the Virtual DataPort Administration Tool. Hope this helps!
Denodo Team
05-02-2020 06:35:16 -0500
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