This section includes the following topics:
- About the Current tab
- How the Current tab is structured
- How the Current tab can help you identify performance problems
About the Current tab
The Current tab displays near real-time information on all sessions that were connected to your Oracle database during the last minute. You can use this tab to monitor your system's current activities and resource consumption and to identify performance problems, such as sessions involved in locks, as they occur.
The Current tab provides answers to the following types of questions: "How many sessions are currently running," or "Why doesn't my application work when I click OK?"
Using the Current tab, you can monitor current connections to your Oracle instance, check the state of each connection, and identify the resources currently utilized by each session. Further investigation of each session provides a thorough understanding of the SQL statement being executed, the login name executing the statement, the program, and the resource utilization for the session.
If you are working with Oracle Applications, SAP, PeopleSoft, or Siebel and ERP support is installed, the Current tab displays information on the current Oracle activity in relation to the ERP application and users, and specific information on executed views and transactions.
In the Current tab, data on a current session is continuously updated to provide information on what happened during the last minute. Because the displayed session information is derived from a dynamic application, it is recommended to regularly refresh the screen, either manually or automatically, to ensure that the information displayed is up-to-date.
The Current tab displays information on the last minute of activity. For example, if you have worked at your screen for ten minutes and then refresh the information displayed on your screen, you will be able to view new information that occurred during the last minute of activity. Similarly, any items that were previously displayed, but have had no activity in the very last minute (rather than the 10 minutes since the last refresh) will not be displayed again, and so will disappear from the screen.
You can set the display to automatically refresh every few minutes; refresh can either be enabled or disabled from the Settings dialog box. If it is enabled, the display will be refreshed every <n> minutes, where <n> is the number specified in the Settings dialog box.
See About configuring general settings, How most tabs are structured, and About the Dashboard tab.
How the Current tab is structured
The Current tab displays information on a selected entity and its associated entities. For example, if the selected entity is a Session, its associated entities are Statements. The selected entity is always reflected in the Tab heading, which serves as a point of orientation. The highest-level entity you can view information for in the Current tab is an Instance. You can view another instance by selecting it from the Instance list. When you open the Current tab from any tab, it always displays information on the instance level, even if the currently selected entity is not an instance.
About the Main area in the Current tab
The Main area shows comprehensive information on the selected entity. You can choose from several views to examine the entity from different angles. For example, if you are analyzing a session entity, you can focus exclusively on the data displayed in the overview, such as, In Oracle data (default), or choose to view the text for the current statement being run by the session.
About the Association area in the Current tab
The Association area provides corresponding information on the entities associated with the selected entity (displayed in the Main area). For example, you can associate with the Active Sessions related to the selected instance. The selection you make is reflected in the Association area only; the Main area remains unchanged. For some entities, tabs above the Association area enable you to view additional information. For example, the tabs displayed for a session entity are: General, In Oracle, and Connection. Clicking a tab displays different table columns with the same type of associated entities.
From the Association area, you can also drill down to another entity by clicking a table row. A drill down affects the entire tab. When you drill down to another entity, the Tab heading displays the new selection, the Main area displays information on the newly selected entity, and the Association area displays the entities associated with the selected entity.
For example, when you want to view information on a specific active session, from the Association controls, click Active Sessions. The Association area changes to display session-related information. Note that the Tab heading and the Main area remain unchanged.
If you want detailed information on an active session, in the Association area, click the row of the session that you want to view detailed information for. The Tab heading indicates the newly selected entity; the Main area displays In Oracle information on the session you drilled down to, and the Association area shows information on the statements associated with this session. See About Precise for Oracle tabs and About the Dashboard tab.
About examining entities in the Current tab
The Current tab displays information on different entities. This section provides an overview of all entities, their meaning, and their views.
The following entities can be examined in the Current tab:
- Instance
- Session
- Statement
About the Instance entity
The Instance entity shows a summary of all sessions connected to Oracle during the last minute.
Getting an overview of current Instance activities
The Instance Overview displays information on the activity of the instance in the Main area. The following table describes the information displayed in the Instance Overview.
Table 1 Instance Overview
| Item | Description |
|---|---|
| Sessions | Displays information on the following items:
|
| Parallelism | Displays information on the following items:
|
| In Oracle (Last Minute) | Displays information on the following items:
See In Oracle. |
| Overall Activity (Last Minute) | A pie chart illustrating the overall activity of all sessions during the last minute. See Overall activity. |
| Work Types (Last Minute) | If the chosen instance has ERP support installed, this tab also displays a pie chart of work types. |
About associating an Instance with other entities
You can associate an Instance, in the Main area of the Current tab, with the following entities in the Association area:
- Current Sessions. A list of all sessions that were connected during the last minute.
- Active Sessions. A list of all sessions that were connected and spent some time executing In Oracle during the minute.
These lists of sessions are each divided into different sets of information, showing different aspects of the sessions. Each set is accessed by a tab.
The following table describes the information shown on Instance Association tabs.
Table 2 Instance Association tabs
| Tab | Columns |
|---|---|
| General | Displays the following table columns:
See In Oracle. |
In Oracle | Displays the following table columns:
See In Oracle. |
| Connection | Displays the following table columns:
See In Oracle. |
Precise for Oracle retrieves the displayed information from Oracle's V$SESSION table. If this table does not contain relevant data for a specific cell in the Association table, this cell is not populated with data.
By clicking a row in the Association table, you can drill down to the specific session. See About the Session entity.
About the Kill Session process
The Kill Session process is executed by the Kill Session button. This button enables you to kill the selected session. You can instruct Oracle to execute this command immediately (using the Oracle Alter System Kill Session Immediate command) or during the time of less activity (using the Oracle Alter System Kill Session command).
To perform the Kill Session during the time of less activity
- On the general tab of the Instance Association, select the session that needs to be killed.
- Click Kill Session.
- In the dialog, insert the Oracle DBA user name and password.
- Click OK.
To perform the Kill Session immediately
- On the general tab of the Instance Association, select the session that needs to be killed.
- Click Kill Session.
- In the dialog, insert the Oracle DBA user name and password.
- Mark Kill immediately.
- Click OK.
About the Session entity
The Session entity displays information on a single connection with Oracle.
About the overview of current and active sessions
The Session Overview displays general information on the session.
The following table describes the information displayed in a Session Overview.
Table 3 Session Overview
| View area | Description |
|---|---|
| Session | Displays information for the following items:
See In Oracle. |
| Connection | Displays information for the following items:
|
| In Oracle (Last Minute) | Displays information for the following items:
|
About the text of a current or active session
The Text view displays the SQL text for the statement that the session is currently executing, if any.
About associating a session with other entities
You can associate a Session, in the Main area of the Current tab, to different entities in the Association area. The information displayed is divided into different sets that show different aspects of the entity. Each set is accessed by a tab.
The following table describes the entities that are available in the Association area.
Table 4 Association area entities
| Entity | Description |
|---|---|
| Statements | Displays a list of statements run by the session during the last minute. |
| Sessions Involved in Lock | Displays a list of other sessions locking or locked by this session during the last minute. Three of the tabs displayed here are the same as those displayed for a regular session. In addition, the Lock tab displays locking information that is equivalent to the information displayed in Oracle's V$SESSION_WAIT table. For more information, see the Oracle documentation. |
| Parallel Query Server Sessions | Displays Parallel Query Coordinator or Parallel Query Slave sessions associated with this session during the last minute. The tabs displayed here are the same as those displayed for a regular session. See About associating an Instance with other entities. |
If you drill down to a Parallel Query Server process, the Main area displays information on this session. You can then identify the Parallel Query Coordinator Session using the Association controls.
The following table explains the information that is displayed on the tabs in the Association area, when the Statements entity is selected.
Table 5 Statements Association area table
| Tab | Columns |
|---|---|
| Statement | Displays the following table columns:
See Statement identifier vs. Oracle hash value and In Oracle. |
| In Oracle | Displays the following table columns:
See Statement identifier vs. Oracle hash value and In Oracle. |
| Statistics | Displays the change in Oracle statistics for the statements in the last minute. See Oracle statistics usage within Precise for Oracle. |
The following table explains the information that is displayed on the Lock tab in the Association area, when the Sessions Involved in Lock entity is selected.
Table 6 Lock tab information
| Column | Description |
|---|---|
| Program | Name of the program connected to Oracle. |
| Session ID | ID of the session. |
| In Oracle (Last Minute) | Bar chart showing the In Oracle breakdown for the session. |
| Status | Indicates whether the session is waiting for or holding the lock. |
| type | Transaction type: TX, TM, and so on. This information is derived from the P1 parameter in the V$SESSION_WAIT table. |
| Mode | Transaction mode: Exclusive, Shared, and so on. This information is derived from the P1 parameter in the V$SESSION_WAIT table. |
| ID1 | This information is equivalent to P2 parameter in the V$SESSION_WAIT table. |
| ID2 | This information is equivalent to P3 parameter in the V$SESSION_WAIT table. |
| Object | Locked object, if appropriate. |
| Text | Portion of SQL text for the session being locked. |
About the Statement entity
The Statement entity, in the Current tab, displays information on a single SQL statement that has been run by a session in the last minute or is still running. You cannot associate a statement with any other entity. This implies that if the Main area displays information on a statement, the Association area remains blank. See About Precise for Oracle tabs.
Getting an overview of current Statement entities
The Statement Overview displays general information on a single SQL statement. The following table describes the information displayed in a Statement Overview.
Table 7 Statement Overview
| View area | Description |
|---|---|
| Statement | Displays information on the following items:
|
| In Oracle (Last Minute) |
|
| Overall Activity (Last Minute) | A pie chart illustrating the overall activity of the statement during the last minute. See Overall activity. |
| Text | The SQL text of the statement. |
About the text of a statement
The Text view displays the SQL text of the statement.
About statement-related statistics changes
The Statistics view displays a list of the changes that occurred in the Oracle statistics for the statement during the last minute. See Oracle statistics usage within Precise for Oracle.
The following table describes the information displayed in the Statement Statistics view.
Table 8 Statement Statistics view
| Column | Description |
|---|---|
| Statistic | Oracle statistic name |
| Value | Statistic value |
How the Current tab can help you identify performance problems
You can identify a performance problem by doing one or more of the following:
- Examining resource consumption of an entire instance
- Examining a single connection
- Resolving a locking situation
Examining resource consumption of an entire instance
The Current tab displays near real-time information on all sessions that were connected to your Oracle database during the last minute. Usually you will use this tab to monitor the system's current activities and resource consumption, and to identify performance problems, such as sessions involved in locks as they occur.
The following example shows how to examine resource consumption of an instance. By examining the current activity at an instance level of display, you can see how it is currently behaving and determine if there is an overall problem that affects all sessions or if there is a problem with specific sessions. For this example, the Main area of the Current tab shows the top two sub-states (in the Sub-State column) for the instance's In Oracle time as Using CPU and Redo Log Buffer Wait.
To examine resource consumption of an entire instance
- In the Instance list, choose the instance you want to analyze.
Do one of the following:- On the View controls in the Main area, click Overview. This will show you a breakdown of resource consumption for the last minute.
- On the View controls, click Statistics to analyze the current statistics of the selected instance.
- In the Main area, check for any unproductive wait states. In our example, the sessions on average (in the % column) are spending roughly a third of their time (34.91%) waiting on the redo log buffer.
- To further investigate, launch the Statistics tab. View the Statistics tab to look for system events that relate to the redo log buffer. Launch to the Statistics tab, in context, to view additional statistical information for any selected instance.
- In the Association area, move the cursor over the In Oracle bar in the list of Active Sessions to display a ToolTip that shows which sessions are spending the majority of their time waiting on Redo Log Buffer Wait.
- Check how much time is spent using CPU. If all other wait states have been eliminated, obviously this will be 100%; therefore, it is important to look at the actual time (in hh:mm:ss), in the Main area, as well as the percentage value. High CPU usage can indicate excessive logical I/O operations.
- To further investigate, open the Activity tab. Try tuning any SQL with a high Using CPU time and high values for the statistics consistent gets and db block gets.
Examining a single connection
You can also monitor current connections to your Oracle instance, check the state of each connection, and identify the resources currently utilized by each session.
The following example shows how to examine a single connection. For this example, the Association area of the Current tab displays the sub-state Using CPU in the Active Sessions list. To examine a single connection
- In the Instance list, choose the instance you want to analyze.
- In the Association area, drill down to the session whose connection you want to analyze. For an example, click the top session ID 10 (in the Session ID column), in the Active Sessions list, for the sub-state Using CPU. In this example, we see all the statements that the selected Session entity has executed in the last minute, or is possibly still executing. The top statement is mainly using CPU and waiting for I/O.
- Continue your analysis by examining its resource breakdown. To further investigate, in the Association area, click the Tune icon in the row of the top statement. Clicking the Tune icon opens the SQL tab for tuning this statement.
Resolving a locking situation
You can view any sessions that are locked in the Current tab. Then you can fully investigate the situation to determine the type of lock and which session is holding the lock.
In the Main area, the following example shows three sessions (shown in the Sessions column) that have waited for a row lock over the last minute. The time waited (shown in the Time column) is 1 minute 57 seconds or 100% of the total In Oracle time for the instance.
In the Association area, three active sessions are in the state of a row lock wait. For our example, Session 117 (the top locked session shown in the Association area) is attempting to execute and UPDATE on the CUSTOMER table (shown in the Program column).
To resolve a locking situation
- In the Instance list, choose the instance you want to analyze.
- On the Association controls, in the Association area, you can associate Session 117 with the other Sessions involved in the lock. For an example, Session ID124 is holding the lock in Exclusive mode.
- Using the Association controls, you can now drill down to see the statements being executed by the session that is holding the lock (Session ID 124).
For our example, in the Main area, you can see that the holding session (for Duration) has not run any statements in the last 15-minute time slice, meaning that the UPDATE to the CUSTOMER table (for Program) was executed earlier but that the session has not yet issued a COMMIT to release the row lock.