[jira] [Created] (ZEPPELIN-4201) JDBC documentation for common.max_rows not accurate

["Jia Long Loh (JIRA)" <ji...@apache.org>]

Jia Long Loh created ZEPPELIN-4201:
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             Summary: JDBC documentation for common.max_rows not accurate
                 Key: ZEPPELIN-4201
                 URL: https://issues.apache.org/jira/browse/ZEPPELIN-4201
             Project: Zeppelin
          Issue Type: Bug
          Components: documentation
    Affects Versions: 0.8.1
            Reporter: Jia Long Loh


In the documentation for [0.8.1|https://zeppelin.apache.org/docs/latest/interpreter/jdbc.html], it is stated that `common.max_count` is used to control the number of output rows from the jdbc.

However, a recent change [here|https://github.com/apache/zeppelin/commit/9f5cf17bdd09c400dc06679bbc61d381fa0a8c56#diff-ecdae8ee9594a5c4b21a3c217a3f130cR720] to 0.8.1 has resulted in `setMaxRows` using the MAX_ROWS_KEY = "zeppelin.jdbc.maxRows". Rows above 1000 seem to be silently dropped as per the documentation [here|https://docs.oracle.com/javase/8/docs/api/java/sql/Statement.html#setMaxRows-int-].

This is very misleading (and even quite dangerous), as many people would assume that as per the documentation, it is common.max_count that controls the number of rows, and because the other rows are silently dropped, this could result in inaccurate results.

We should highlight in the documentation that zeppelin.jdbc.maxRows needs to be set to control the number of rows the jdbc returns.



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