unable to find columns error when trying to read meta data from a JDBC data source

Hi, I know that the Generic JDBC data-source, is not fully supported (as it seems). However, it seems like there are some issues with it. I am working with a JDBC driver which is written "by the book" (meaning all the interfaces are implemented as needed, and tested correctly vs java programs and sql-tools like squirel sql and other tools). For some views which are supposed to be well exposed through the JDBC, Denodo s not able to read them, and throws an "ExInternalError", which while looking at the details looks like : com.denodo.util.jdbc.DatabaseInspector [] - describeTable (connection, string, string) java.sql.SQLException: Unable to find columns at com.denodo.util.jdbc.DatabaseInspector.describeTable(DatabaseInspector.java:1043) ~[denodo-commons-jdbc.util.jar:6.0.4] if more information is needed I'll be happy to supply. Moreover, it seems that if I try to bypass this by creating a view by query, Denodo is stuck in something which seems like inifinite loop while trying to create the base view. (This is not the 1st time I see this issue of what seems to be a hanging process, I've seen this happening with other JDBC's drivers)
18-04-2017 07:43:58 -0400

3 Answers

Hi, what is this JDBC driver that is written “by the book” that you are talking about? If you provide some info about the source / version someone in the Community may be able to help you. Also when you mentioned "I’ve seen this happening with other JDBC’s drivers" what other JDBC drivers? Again any information about the sources and versions will help. As you understand just saying driver "by the book" or "other JDBC drivers" will be too much guessing for everybody on finding what is what you are doing
19-04-2017 21:11:31 -0400
The jdbc driver is Anchormen for elasticsearch (called : sql4es), you'll be able to easily find it in github. I was hoping to get answer about the logs, data which is missing in order to solve those issues, as the Denodo's framework hides the exception it gets from you, and throws out some generic meaningless Errors, which do not help much with understanding. Actually the specific scenario is trying to query over elasticsearch aliases, which is fully supported with this driver, and tested successfully through tools like squirelSQL
20-04-2017 07:59:38 -0400
Hi, In order to query over aliases in ElasticSearch, I would 1. Create a base view on an ElasticSearch alias as “**select * from alias_name**” 2. Then, edit the VQL manually and change the SQL Sentence to “**select * from alias_name” by RELATIONNAME =“alias_name**” By doing this, base views on aliases will work exactly the same like base views on tables created using introspection. Hope this helps!
Denodo Team
11-01-2019 06:46:43 -0500
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