Using logcontroller and useful log categories

Applies to: Denodo 8.0 , Denodo 7.0 , Denodo 6.0
Last modified on: 31 May 2020
Tags: Administration Logs Server configuration

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Goal

This document explains how to use the predefined LOGCONTROLLER stored procedure and some useful log categories.  

Content

Denodo Virtual DataPort uses the logging library Apache Log4j to log the activity of the Virtual DataPort server and its Administration Tool. Log4j allows defining several categories on which the log level will be specified independently.

By default, the Virtual DataPort Server logs are stored in <DENODO_HOME>/logs/vdp and the Administration Tool logs, in <DENODO_HOME>/logs/vdp-admin. The configuration of Log4j of the Virtual DataPort server is controlled by the file log4j2.xml (<DENODO_HOME>/conf/vdp) and for the Administration Tool by the file log4j.xml (<DENODO_HOME>/conf/vdp-admin).

 

You can change the log level of a category in the VDP server without restarting it by calling the stored procedure “LogController”. This stored procedure changes the log level for a certain log category of the logging engine used by Virtual DataPort at run time. The changes performed by this procedure are lost when the Server is stopped. Administration privileges are required to call this stored procedure.

 

Syntax: LogController (<logCategory>, <logLevel>)

  • logCategory – the category of the log. The package of the Java classes to log information from. You can see some of the lists of log categories in log4j2.xml file.
  • logLevel – type of message to be logged for the category: ‘TRACE', 'DEBUG', 'INFO', ‘WARN', 'ERROR', 'FATAL'.

 

Log categories

 

The log categories have a hierarchical structure when a log level is set for a category all its subcategories will also be set to the same log level.

 

For example, on executing

CALL LOGCONTROLLER('com.denodo', 'INFO')

 

all the classes under the “com.denodo” category will be set to the INFO log level and its subcategories will also log to the same level.

 

The “com.denodo” log category can be used when we are not aware of which log category has to be used since it displays all the subcategories in the VDP servers.

 

The following is a list of useful log categories:

  • com.denodo.vdb.cache: To get information about the cache.
  • com.denodo.vdb.engine.storedprocedure: To see log messages of stored procedures.
  • com.denodo.vdb.engine.thread: To show information about the pool of threads.
  • com.denodo.vdb.engine.wrapper.raw.[datasourceType]: To get the data source access information. Data sourceType could be arn, df, essbase, gs, html (itpilot), jdbc, json, ldap, my (custom), odbc, olap, salesforce, sapbwbapi, saperp, ws or xml.
  • com.denodo.vdb.engine.swap: To get information about swapping.
  • com.denodo.vdp.requests: To get a log file with the sentences that are executed in the server.
  • com.denodo.vdb.vdbinterface.server.odbc: To get information about ODBC connections to the VDP server (Northbound connections).

References

Virtual DataPort Administration Guide: Configuring the Logging Engine

Advanced VQL Guide: LOGCONTROLLER

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