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Dariusz Owczarek

Meaning of Oracle Key Statistics - 0 views

skillport.books24x7.com/...viewer.asp

dba edba oracle performance

shared by Dariusz Owczarek on 08 Jun 10 - Cached
  • Statistics are somewhat fallible in that they are seldom 100 percent accurate, but in most cases they do sufficiently indicate what was intended. Be sure you understand what each statistic represents and the units used (there is a big difference between microseconds and centiseconds).
  • Time-breakdown statistics (Time Model) make it significantly easier to determine the type of operations that are consuming resources in the database.
  • DB time: Time spent by all user processes in the database (that is,. non-idle wait time + CPU time).
  • ...11 more annotations...
  • DB CPU: Time spent by all user processes on the CPU, in Oracle code. On most systems, the majority of time will be spent in DB CPU, SQL execute elapsed time, or PL/SQL execution elapsed time (and possibly Java). Time spent in parse and connection management should be low, so if the levels indicate a high percentage of DB time, a problem exists in the relevant area. You can use this data to correlate with Top 5 Timed Events and Load Profile.
  • Database time (DB time) is an important time-based statistic: it measures the total time spent in the database by active sessions (that is, foreground user processes either actively working or actively waiting in a database call). DB time includes CPU time, I/O time, and other non-idle wait time.
  • Because DB time represents the sum of the time that all sessions spend in database calls, it can easily exceed the elapsed wall-clock time.
  • The objective of tuning an Oracle system could be stated as reducing the time that users spend in performing actions in the database, or simply reducing DB time.
  • Wait time is artificially inflated when the host is CPU bound because the wait time includes the actual time spent waiting (for example, waiting for a disk I/O), as well as the time spent by the process in the OS run-queue waiting to be rescheduled.
  • Therefore, when the host is CPU bound, it is important to reduce CPU utilization before addressing wait-related problems, because otherwise you may be addressing the wrong problem.
  • You can use ASH data to estimate DB time when the actual DB time is not available—for example, if a session has exited. Because ASH samples active sessions every second, you can estimate DB time (in seconds) to be the number of ASH samples counted.
  • V$OSSTAT is OS-related resource utilization data that the Oracle server collects. The statistics available vary by platform. You can use V$OSSTAT to determine CPU utilization (BUSY_TICKS and IDLE_TICKS), and also compare this to the host's CPU utilization statistics. Also look for high OS_CPU_WAIT_TIME, which may indicate the host is CPU bound.
  • V$OSSTAT statistics can be compared with the Time Model statistics, for example to determine how much of the total CPU used on the host is attributable to this instance: DB CPU / BUSY_TICKS.
  • note that the units for these two statistics differ.
  • In 10g, each wait event (V$SYSTEM_EVENT) is classified into one of nine wait classes: Application, Commit, Concurrency, Configuration, Network, Other, System I/O, User I/O, and Idle. The class names are reasonably self-explanatory except Other, which is a catchall bucket for wait events that should not ever contribute any significant wait time.
jameswaltz

They Fixed My Slow Computer - 1 views

My computer started running so slow that it takes me 10 minutes just to open a site. So I called Fix Slow Computer Today to help me with my concern. They have expert computer technicians who can fi...

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started by jameswaltz on 13 Sep 11 no follow-up yet
samantha armstrong

FixComputerpProblemsSite Surely Knows How to Fix Computer Problems! - 1 views

I was having problems with my laptop before. Good thing FixComputerpProblemsSite helped me fix it. And they are really the experts when it comes to solving any computer related issues. They can eas...

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started by samantha armstrong on 10 Jun 11 no follow-up yet
paul silmonet

Instant Fix Slow Computer Solutions - 0 views

I bought a brand new PC with good specifications just last month. But only three weeks of use, I noticed that my PC froze and slowed down a bit. For the next three days, it continued to slow down. ...

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started by paul silmonet on 09 Jun 11 no follow-up yet
Dariusz Owczarek

Oracle Critical Patch Update - October 2009 - 0 views

www.oracle.com/...cpuoct2009.html

dba oracle

shared by Dariusz Owczarek on 21 Oct 09 - No Cached
  • Dariusz Owczarek on 21 Oct 09
     
    A Critical Patch Update is a collection of patches for multiple security vulnerabilities. It also includes non-security fixes that are required (because of interdependencies) by those security patches. Critical Patch Updates are cumulative, except as noted below, but each advisory describes only the security fixes added since the previous Critical Patch Update. Thus, prior Critical Patch Update Advisories should be reviewed for information regarding earlier accumulated security fixes.
Dariusz Owczarek

Oracle OS statistics - 0 views

www.dba-oracle.com/t_os_statistics.htm

dba oracle

shared by Dariusz Owczarek on 16 Oct 09 - Cached
  • Dariusz Owczarek on 16 Oct 09
     
    The speed of disk access, the backlog of CPU enqueues, network latency and RAM swapping can all be the root cause of an Oracle performance problem, and no amount of tuning can fix a problem that is at the OS layer, external to Oracle. Oracle has two main ways to collect OS information...
pctechsupport

Trusted PC Tech Support - 1 views

Computers are the most essential commodity for me, especially for my business. That is why whenever I experiences computer trouble, I would really look for a PC tech support specialist to fix my co...

started by pctechsupport on 13 Sep 11 no follow-up yet
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