The Activity Summary window gives a quick access to the activity of an Oracle instance.
System Number of system sessions. Active Number of sessions that are currently active. Inactive Number of sessions that are currently inactive Blocking Number of session blocking other sessions
% Busy Server Processes
Dispatcher Processes that coordonate the allocation of shared servers to client tasks. Shared A shared server process can service multiple user processes. Parallel Query Support execution of parallel queries and DML statements.
SGA Memory (MBytes)
Latch Latch are Oracle internal locks which protect memory structures in the SGA. The Latch hit rate shows the proportion of times that requests for latch are satisfied without waiting. Buffer cache Percentage of time a required data block is found in the buffer cache. Library cache The percentage of reads or executions that do not result in reparsing or reloading. Library cache get The frequency with which a matching SQL statement is found in the shared pool when a SQL parse request is issued by a session. Library cache pin The frequency with which a SQL statement executed by a session has been found in the shared pool. Dictionary cache The frequency with which a database object structure is found in the shared pool when a SQL statement is issued.
Db file Occurs when a session issues an I/O request against an Oracle datafile.
(db file parallel write + db file scattered read + db file sequential read + db file single write)
Log file sync/write When a COMMIT is issued, the redo log writer flushed the content of the redo log to the redo file. The session waits for the write to complete to return control.
(log file parallel write + log file sync)
Log file space/switch Occurs when there is not enough free space in the redo log buffer to make a redo log entry.
(log buffer space + log file switch completion)
Buffer busy Occurs when a session tries to access a block currently used by another session. Latch free Occurs when a session tries to acquire a latch currently held by another session. Enqueue Occurs when a session waits to obtain a lock. Direct path I/O During Direct Path operations, the data is asynchronously written to the database files. At some stage the session needs to make sure that all outstanding asynchronous I/O have been completed to disk.
(direct path read + direct path write)
Control file I/O Occurs when a session accesses the control file.
(control file parallel write + control file sequential read)
I/O (per second)
Datafile reads Number of reads from the datafiles Consistent reads The number of blocks in memory that are read in consistent mode. Consistent mode reads are usually associated with query activity. Current reads The number of blocks in memory that are read in current mode per second. Current mode reads are usually associated with updates. Block changes The number of database blocks in memory (SGA) that are modified per second.
SQL*Net (bytes per second)
Sent to client The rate at which data is being transferred from Oracle server processes to user processes across the SQL*NET interface. Recv from client The rate at which data from user processes is being transferred to the Oracle server across the SQL*NET interface.
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