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Issue in select clause while executing joined tables from teradata and SAP Hana

Hi, I have joined tables from teradata and SAP Hana, i was able to execute the view and get data if i add a where clause in the query. but when i run select * from table query it is running for a long time and throws error as 'error in join'. also not able to import the table in power BI. Performance for the tables is very low. Please provide some suggestions. THanks!
user
11-08-2020 10:29:30 -0400

1 Answer

Hi, I would check the query’s execution trace to find each data source's execution time and isolate the datasource which is requiring a lot of processing. This would help me to determine which parts of the query might require further optimization. Also I would enable the [Denodo Monitor Tool](https://community.denodo.com/docs/html/document/denodoconnects/7.0/Denodo%20Monitor%20Reports%20-%20User%20Manual) to monitor the Server performance. When I perform the join that result in a large number of rows, I make use of the different query optimization methods that are available, such as: 1. [Optimizing Join Operations](https://community.denodo.com/docs/html/browse/7.0/vdp/administration/optimizing_queries/optimizing_join_operations/optimizing_join_operations#optimizing-join-operations). 1. [Cost-based optimization](https://community.denodo.com/docs/html/browse/7.0/vdp/administration/optimizing_queries/cost-based_optimization/cost-based_optimization). 1. [Data movement](https://community.denodo.com/docs/html/browse/7.0/vdp/administration/optimizing_queries/data_movement/data_movement). 1. [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). 1. [Parallel Processing](https://community.denodo.com/docs/html/browse/7.0/vdp/administration/optimizing_queries/parallel_processing/parallel_processing). I would recommend you to take a look at the Knowledge Base article Best Practices to maximize performance - “[Configuring the Query Optimizer](https://community.denodo.com/kb/view/document/Best%20Practices%20to%20Maximize%20Performance%20II:%20Configuring%20the%20Query%20Optimizer?category=Best+Practices)” and “[Detecting Bottlenecks in the Query](https://community.denodo.com/kb/view/document/Best%20Practices%20to%20Maximize%20Performance%20IV:%20Detecting%20Bottlenecks%20in%20a%20Query?category=Best+Practices)” which discusses query optimization and detecting bottleneck in very detail. Hope this helps!
Denodo Team
12-08-2020 08:31:54 -0400
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