Spotlight on Oracle 10.10 - Release Notes

When a block is about to be flushed from the buffer cache, Oracle will attempt to insert the block into flash cache.

This is the number of blocks per second successfully inserted into the flash cache. This value is taken from the statistic 'flash cache inserts' from V$SYSSTAT.

Number of blocks per second a session has read from the flash cache. This value is taken from the 'physical read flash cache hits' statistic from V$SYSSTAT.

When a block is about to be flushed from the buffer cache and the DBWR is busy writing dirty buffers to disk, the flash cache insert is skipped.

This is the number of blocks per second the flash cache insert skipped due to the DBWR being overloaded. This value is taken from the 'flash cache insert skip: DBWR overloaded' statistic from V$SYSSTAT.

When a block is about to be flushed from the buffer cache, but the flash cache insert is skipped due to other reasons (not because the DBWR is overloaded or because the block already exists in flash cache).

This is the number of blocks per second the flash cache insert skipped due to other reasons.

This value is the sum of the following statistics from V$SYSSTAT:

• flash cache insert skip: corrupt
• flash cache insert skip: modification
• flash cache insert skip: not current
• flash cache insert skip: not useful

Tip: To see the values for these individual statistics, click the Statistics tab.

The number of blocks per second evicted from the flash cache. The most common reason for blocks to be evicted from the flash cache is because the block was modified.

This value is the sum of the following statistics from V$SYSSTAT:

• flash cache eviction: invalidated
• flash cache eviction: buffer pinned
• flash cache eviction: aged out

Tip: To see the values for these individual statistics, click the Statistics tab.

Amount of time sessions are active on the database. This value is taken from the statistic 'DB time' from V$SYS_TIME_MODEL.

Amount of time spent doing single block reads from flash cache. This value is taken from wait event 'db flash cache single block physical read' from V$SYSTEM_EVENT.

Amount of time spent doing multi block reads from flash cache. This value is taken from wait event 'db flash cache multiblock physical read' from V$SYSTEM_EVENT.

Amount of time the DBWR spent waiting on flash cache write to complete.

Consider turning on asynchronous I/O using the 'filesystemio_options' parameter. This value is taken from the wait event 'db flash cache write' from V$SYSTEM_EVENT.

This metric indicates that sessions are trying to update a block that is currently being written to flash cache. A high rate of flash cache write complete waits means that writing to the flash cache is holding up sessions from performing updates.

This value is taken from wait event 'write complete waits: flash cache' from V$SYSTEM_EVENT.

User session ID.

Oracle database account of the started session.

Program running the session.

Currently executing module name set by DBMS_APPLICATION_INFO.SET_MODULE.

Number of reads from flash cache per second.

Number of reads from disk per second.

Total time spent doing reads from flash cache.

Total time spent doing reads from physical disk.

Time that it would have taken to read blocks from physical disk that were actually read from flash cache.

This value is calculated by taking the difference in latency for disk reads compared to flash cache reads, and multiplying it by the number of flash cache reads.

Total amount of time the session was active.

Total number of reads from flash cache.

Time, in microseconds, taken to read a single block from flash cache.

Time, in microseconds, taken to read a single block from physical disk.

Total number of block changes the session has performed.

Amount of time spent using CPU.

Number of logical reads per second in the past sampling interval. This includes all requests for database blocks, irrespective of whether they were found in the database cache.

Name of the computer on which the client is running.

Total number of multi block reads from flash cache.

Total time spent doing multi block reads from flash cache.

Number of multi block reads from flash cache per second.

Operating system user for the client.

The number of physical reads initiated by the session.

Serial number of the session. SIDs can be reused after the session disconnects, but the combination of SID and Serial number is always unique.

Operating system process ID for the Oracle server process.

Total number of single block reads from flash cache.

Total time spent doing single block reads from flash cache.

Object owner and name.

Number of reads from flash cache (optimized physical reads).

Number of reads from physical disk (physical reads - optimized physical reads).

Number of blocks in the flash cache.

Number of blocks in the buffer cache.

Total number of blocks in both caches. Note this is not the addition of the last two columns as some blocks could be in both caches.

Total number of blocks on physical disk for the object.