Istvan Toth created CALCITE-5009:
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             Summary: Remove transaparent jdbc connection re-creation code
                 Key: CALCITE-5009
                 URL: https://issues.apache.org/jira/browse/CALCITE-5009
             Project: Calcite
          Issue Type: Bug
          Components: avatica
            Reporter: Istvan Toth


Currently, if the server-side JDBC connection goes away for any reason
 * Avatica connection cache expiry
 * LB/HA Failover
 * Some problem with the "real" connection

we attempt to create a new "real" JDBC connection, and continue using that 
instead of the original connection

[https://github.com/apache/calcite-avatica/blob/fbdcc62745a0e8920db759fb6bdce564d854e407/core/src/main/java/org/apache/calcite/avatica/AvaticaConnection.java#L796]

This is fine for most read-only connections, but it can break transaction 
semantics, which is captured in the "real" connection object.


{noformat}
conn.setAutocommit(false)
stmt = conn.createStatement()
execute(insert A)
//Connection lost and object recreated which now proxies a new "real" connection
execute(insert B)
conn.commit()
//We have lost "insert A"{noformat}
I'm not sure if we synchronize autocommit state of the new connection to the 
lost one or not, but it's bad either way.

 

We should either completely drop this feature, add some logic that avoids it if 
there is an open transaction and/or only allow it for connections that have the 
readOnly flag set.



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