Information and Events on the Running of Statements

The RequestsManagementInfo MBeans provide information about the “read only” and Data Manipulation Language (DML) queries processed by a database of the Server. These MBeans are located in com.denodo.vdb.management.mbeans > RequestsManagementInfo > database name.

Attributes of the RequestsManagementInfo MBeans

There is a RequestsManagementInfo MBean for each database and they have the following attributes:

  • DatabaseName. Name of the database.

  • MaxRequests. Maximum number of requests exported at the same time in the MBean. Each request appears as an attribute of the form Request<i>.

  • TotalRequests. Total number of requests processed since the launch of the Server.

  • ActiveRequests. Number of active requests.

Notifications of the RequestsManagementInfo MBeans

The MBean RequestsManagementInfo of a database generates two types of notifications:

  1. Notification that indicate the beginning of a request.

  2. Notification that indicate the end of a request.

Client applications can subscribe to these notifications. To subscribe to these in Java Visual VM, open the MBean RequestsManagementInfo of the database, click the tab Notifications and click Subscribe.

These notifications have the following attributes:

  • Timestamp. Instant at which the notification is generated.

  • Type. Type of notification. Its value can be startRequest or endRequest.

  • UserData. Compound element. Its properties contain information about the request sent to this database. To see them, expand the node of this MBean in the MBeans browser. If there are no Request nodes, it means that this database has not received any request yet. These MBeans have the following properties:

    • AccessInterface. Type of client that performed the request. Possible values of the attribute “access interface” lists the possible values of this attribute.

    • Cache. true if the query has accessed the cache during its execution. false otherwise.

    • ClientIP: IP address of the client. In case of Web services this is the IP address of the final client. I.e. the one that sends the HTTP request.

    • Completed. true if the query finished correctly. false otherwise.

    • DatabaseName. Name of the database on which the statement is executed.

    • Elements. Name and database of the views/stored procedures referenced in the query. This property has the format “<database of the view/stored procedure>”.”<name of the view/stored procedure>”.

    • EndTime. Moment at which the statement finished its execution.

    • Identifier. Identifier of the request. This number is unique but it may not be consecutive (i.e. a request may have identifier “123” and the next one, “125”). When the Server is restarted, this value is restarted to 1.

    • NumRows. Number of rows returned by the query.

    • Queued. true if this query has been queued because the limit of maximum number of concurrent queries has been reached. false otherwise.

    • RequestType. This indicates the type of statement. It can take the following values: SELECT BASE VIEW, SELECT VIEW, QUERY WRAPPER, CALL STOREDPROCEDURE, INSERT, UPDATE or DELETE.

    • SessionId. Id of the session that this request belongs to.

    • StartTime. Instant at which the Server received the query.

    • State. This attribute stores the state of the top node of the execution plan and its value can be OK, ERROR or PROCESSING. Note that the state of the top node can be OK and the state of other nodes be ERROR. For example, if one of the branches of a JOIN query fails and does not return results, its state is ERROR. However, as the JOIN operation finishes correctly, its state is OK. In this scenario, the attribute State is OK and Completed is false.

    • Swap. True if the server swapped the intermediate results to disk during the execution of the query. False otherwise.

    • TransactionId. Identifier of the transaction. Empty string if this request was not part of a transaction.

    • UserAgent. Name of the application that performed the request. Setting the user agent in the application is useful to know which application opens each connection. The section Setting the User Agent of an Application explains how to set this.

    • UserName. ID of the user running the statement.

    • VQLQuery. VQL code for the statement.

    • WaitingTime. Number of milliseconds the query was waiting in the queue of queries before the Server began executing it. A query is hold in the queue of queries when the limit of concurrent requests is reached. See more about this limit and how to increase it in the section Limiting the Number of Concurrent Requests.

    • WebServiceName. If this request was sent by a SOAP or REST web service published by this Denodo server, this is the name of the web service. If the request comes from a different type of client, this is an empty string.

  • SeqNum. Identifier of the notification.

  • Message. In this type of notification, it takes the value Started the request or Finished the request.

  • Event. This will be

    javax.management.Notification[source=com.denodo.vdb.management.mbeans:type=RequestsManagementInfo,databaseName=<dbname>][type=endRequest][message=Finished the request '<i>']
    

    , where <dbName> is the name of the Virtual DataPort database and <i> is the statement identifier.

  • Source. MBean name.