Similar Questions

• How to increase! Buffer Cache Hit Ratio

  Hi all
  
  my database performance is low how to increase the buffer Cache Hit Ratio
  
  Database version: 8.1.7.0.0
  ~ Data upward since: 09:56:23, September 23, 2010
  ! Buffer Cache Hit Ratio: 81.6157
  ~ The library Cache Miss Ratio: 0.03
  ~ Dictionary Cache Miss ratio: 6.6979
  
  [Use of the shared pool] Exec time 0 seconds
  ~ Total unused Mb: 251.88
  ~ Total MB used: 98.12
  ~ MB total: 350
  ~ % Pool used: 28.04

  Buffer Cache Hit Ratio is an indicator of sense of the performance of the system.
  Are there users complain? If there are no complaints, there is also no problem.

  The best way to increase the buffer Cache Hit Ratio is executing statspack identify offensive SQL and to grant this SQL offensive.

  ----------
  Sybrand Bakker
  Senior Oracle DBA

• Database buffer cache hit ratio is less than 90%

  Hi all
  
  For the following query I get the bottom 90%
  
  SELECT ROUND (((1-(phy.) VALUE /(cur.) VALUE con. ((VALUE))) * 100), 2) "HIT RATIO" +.
  OF SYS.v_$ sysstat news,.
  SYS.v_$ sysstat con,.
  SYS.v_$ sysstat phy
  WHERE cur.NAME = 'db block gets. "
  AND con.NAME = "becomes" compatible
  AND phy.NAME = 'physical reads. "
  
  RATE
  ----------
  81,79 +.
  
  Please advice me what could be the reasons and how do I make more than 90%.
  I have access to metalink. I raise this issue with Oracle metalink?
  
  Thank you and best regards,
  Arun Kumar

  user8853422 wrote:
  I'm afraid I can't do that... because I'm still new to DBA... What is my understanding that if buffer cache hit ratio is high, it means that server process do not need to recover data from data files, instead it will look in the buffer cache. Time is less and therefore better performance.

  Your understanding is "basically" correct.

  Please correct me if I'm wrong.

  However, your understanding is limited to a set of very specific circumstances. In reality there are times where it may be reasonable to pick up the disc.

  Basically, the concept of a specific BCHR is excellent if you have exactly the same kind of question asked time and time again (limited OLTP) ensure that guests have repeatedly looking at things in memory, or if you have enough memory to fit the entire database AND all potential read consistent blocks in the SGA.

  Anything less and you're looking at compromises.

  And that 'compromise' requirement that throws the usefulness of the BCHR whack. You need to look at the complete picture.

  Therefore, we can honestly say: If you follow your buffer Cache Hit Ratio over a period of time and your workload (transaction rate, type of transaction and competition) remains about the same, then you could grant using BCHR or use it as an indicator of the health of your system.

  But watch the BCHR and say, "this number is good" and "this number is bad" is essentially meaningless.

• Foglight | Monitoring Exchange | EXC IS a Database Cache Hit percentage

  Hello

  In Foglight 5.6.5, for monitoring of Exchange, 'EXC IS Hit percentage of Database Cache' setting alarm message is null.

  No chance, it is a pasive cluster node?

  There is this article

  https://support.quest.com/SolutionDetail.aspx?ID=SOL108087&PR=Foglight

  108087 knowledge article

  RSS subscription

  close

  The solution that you want to subscribe covers a number of software products from Dell. Please choose the one that is of primary interest;

  
   

  Foglight

  Foglight for virtualization Enterprise Edition

  • Return

  • Title

    Rule of Database Cache % Hit EXC triggers alarm for the node of cluster pasive despite no activity

  • Description

  Rule of Database Cache % Hit EXC triggers alarm for cluster node paasive despite no database activity

  • Resolution

  Default ID EXC-646 was recorded and will be evaluated for a future release

  • ID of default

  EXC-646

• Metrics PGA Cache Hit %

  Hi gurus,

  I'm on 10.2.0.4.0 and receive regularly the Metrics PGA Cache Hit percent alert through OEM. Could you please guide me in the identification of the question if these OEM alerts are stopped.

  Kindly let me know what you would need more information.

  SQL > Show sga

  Total System Global Area 6442450944 bytes
  Bytes of size 2093584 fixed
  3640659440 variable size bytes
  2785017856 of database buffers bytes
  Redo buffers 14680064 bytes
  SQL > Show parameter pga

  VALUE OF TYPE NAME
  ------------------------------------ ----------- ------------------------------
  whole large pga_aggregate_target 1500M

  Thanks for your time and your help.

  Kind regards

  DBApps

  DBApps wrote:

  Hi gurus,

  I'm on 10.2.0.4.0 and receive regularly the Metrics PGA Cache Hit percent alert through OEM. Could you please guide me in the identification of the question if these OEM alerts are stopped.

  Kindly let me know what you would need more information.

  SQL > Show sga

  Total System Global Area 6442450944 bytes
  Bytes of size 2093584 fixed
  3640659440 variable size bytes
  2785017856 of database buffers bytes
  Redo buffers 14680064 bytes
  SQL > Show parameter pga

  VALUE OF TYPE NAME
  ------------------------------------ ----------- ------------------------------
  whole large pga_aggregate_target 1500M

  Thanks for your time and your help.

  Kind regards

  DBApps

  I just want to turn off the alert in OEM.  It warns you of a non-issue.  I'd be more concerned about the fact that you are using an old version, not supported in Oracle.

• Cache HIT

  Hello

  We activated the CACHE of OBIEE 11 g through the FMW. Now, how would I know that the request hit the cache

  Run a query and analysis and look at the log file (nqquery.log). If you see the name of the physical table and then he went to the database, then he got the information from the cache. There should also be cache hit 1 in the journal against cache press 0.

• Tuning PGA Cache Hit Percantage

  Hi Experts,
  
  I need your help to increase my cache hit percentage
  
  My version of DB is 9.2.0.1.0 with 8 GB of memory
  
  The SGA size: 560MB
  Overall target of PGA: 128 MB
  
  and put in Cache Hit %: 64,74%
  
  How do I hide my PGA increase %
  
  Here are the results of some Tuning scripts that I found on the web.
  
  Select the name, the value from v$ pgastat;
  
  VALUE NAME
  PGA 134217728 overall target setting
  overall target of the PGA 62281728 auto
  related global memory 6710272
  Total PGA inuse 67956736
  Allocated total PGA 119108608
  PGA maximum allowed 140296192
  total memory of PGA freeable 7208960
  PGA memory freed to OS 7361462272
  Total PGA used to auto workareas 2932736
  Maximum PGA used to workareas auto 25807872
  Total PGA used for manual workareas 0
  Maximum PGA used for manual workareas 0
  during the assignment of the count 0
  the treated bytes 29607550976
  extra bytes read/written 16256915456
  cache hit percentage 64,55
  
  
  Select name c1, c2 count, decode (total, 0, 0, round(count*100/total)) c3
  (select name, count, (total (value) value on (()) sum of v$ sysstat where name like 'activities exec %');
  
  C1 c2 c3
  activities the executions - optimal 475834 100
  executions - onepass 323 activities 0
  activities the executions - multipass 3 0
  
  SELECT turn target_mb (PGA_TARGET_FOR_ESTIMATE/1024/1024),
  ESTD_PGA_CACHE_HIT_PERCENTAGE cache_hit_perc,
  ESTD_OVERALLOC_COUNT
  V $ pga_target_advice;
  
  TARGET_MB CACHE_HIT_PERC ESTD_OVERALLOC_COUNT
  16                     44                     2177
  32                     45                     1923
  64                     68                     133
  96                     72                     0
  128                     73                     0
  154                     81                     0
  179                     81                     0
  205                     81                     0
  230                     81                     0
  256                     81                     0
  384                     81                     0
  512                     81                     0
  768                     95                     0
  1024                     95                     0
  
  Please help me to increase the % of success.

  But still, you can find the optimal plan and tell your developers to implement depends on this plan...

• The Windows Installer Cache is missing

  For awhile, I was unable to install any program who need Windows Installer. It seems that I do not have a folder for the Windows Installer cache. I looked carefully in c:\windows for the "Installer" folder, but it does not exist.

  A 'repair installation ' using a disk upgrade would solve this problem or should I completely reinstall Windows?

  Thank you!

  Hello

  Thank you for the Microsoft Community approach. I understand that you are facing problems with Windows Installer. I will certainly help the question of fixing.

  I suggest you perform the steps in troubleshooting of these links and then check if it solves the problem.

  Solve problems with programs that cannot be installed or uninstalled

  How to solve problems when you install or uninstall programs on a Windows computer

  I hope that helps you fix the problem. If the problem persists, we after return. We would be happy to help you.

• cache database low hit ratio (85%)

  Hi guys,.
  
  I understand that db high cache hit ratio is no indication that the database is in good health.
  The database could be other 'physical' readings due to the listen SQL.
  
  However, can you explain why a ratio / low cache access cannot indicate that the db is unhealthy, such as db additional memory allocated?
  What I think is probably:
  
  1. the database can query various data most of the time. So the data are not yet read older seized cache. Even if I add additional memory, the data could not be read again (from memory).
  2.?
  3.
  
  I'm reluctant to list the databases below 90% as part of the monthly management report successfully. For them, less than 90% means unhealthy.
  If these reports, which will be used in the monthly report, it will be a long article to explain why these ratios can not respond but there is no worry of performance.
  
  As such need your expert advise on that.
  
  Thank you
  
  Published by: Chewy on March 13, 2012 01:23

  Hello

  You said that there is no complaint of the end-user, but that management wants to proactively scan the system. OK, monitoring proactive is a good thing, but you have to understand your system well enough to understand what to monitor. As mentioned Sybrand, if you have a system that everyone is satisfied, it does not matter what is the BCHR.

  So, what to do? Well, the answer is not simple. You must understand your system. Specifically, what are the strategic functions of your system? It doesn't matter if these are the reports that the Finance Office needs, measured in minutes or hours or response time on a special form, measured in second or subsecond response time. The point is, understand your system, what is expected and what is achievable, and then use this information to try to find contracts of service level (SLA). An SLA can read something like "90% of the executions of the sales report will daily complete in 10 minutes or less. It is important to structure the ALS in this way, "x % of executions of task that is completed in minutes of z '. If you simply say "task will be always full minutes z", you are setting yourself up for failure. All systems have variance. It's inevitable. Put between parentheses and boundaries around variance is durable and is a system that you will be able to work with.

  So, in summary:
  1.) define critical tasks.
  (2.) to characterize their performance.
  3.) working with end users and/or management define SLA contracts.
  4.) set up monitors that will measure the performance of the system and warn you if you exceed a SLA.

  Hope that helps,

  -Mark

• Library Cache Tuning

  HI friends,
  I m new to DBA tasks. v have oracle 11g on WIndows xp...
  
  I give me tasks to Tune Library Cache on my live server
  
  I asked rowcache $ V to get the data dictionary cache hit ratio...
  sound * 99% * (ideally the greter b at 90%)
  
  I asked librarycache $ V to get the library cache miss ratio...
  sound * 0.0006% * (ideally less than 0.1 b)
  
  I asked him too librarycache $ v to get the reord below who had problems.
  
  NAMESPACE GETS GETHITS GETHIT_RATIO PINE PINHITS PINHIT_RATIO CHARGING INVALIDATIONS
  AREA OF SQL 43586289 24169038 * 87827805 86643314 55.45* 98,65 122912 42903
  
  Usually gethit_rate should b about 70%, but its 55,45 just for the sql box?
  
  My settings shared_pool_size = 0.
  
  Can you let me know there is this... and what do I do?
  
  Thanks in adance.

  You would grant something that has proved to be a problem. Is there evidence that the library Cache Hit ratio is the performance impact?

  It may be well that the way the application refers to objects through life cycle daily is, the Cache Hit Ratio, not 'seems' to be good.

  The Cache size bookstores automatically takes the value based on the shared pool. If SHARED_POOL_SIZE is 0, then this is to be auto-resized by Oracle based on SGA_TARGET.

  Hemant K Collette

• Missing counters in windows 2012 and 2012 R2

  Hi, I have a script dealing with several Performance counters on windows 2008. But, after moving to Win 2012/2012 R2, my scripts are no more work. It seems that a few counters available in Win 2008 are not more present in 2012 Win/2012R2.

  Counters of my interest are-

  ObjectName = Counter 'Session of Services Terminal Server"="Total bytes.

  ObjectName = Counter 'Session of Services Terminal Server"="Total errors ".

  ObjectName = Counter 'Session of Services Terminal Server"="Total frames ".

  ObjectName = Counter 'Session of Services Terminal Server"="Total Protocol Cache Hit Ratio"

  No idea, how to recover information in 2012/2012R2?  These counters are completely got deleted or any other counter does the same job?

  Ask here

  TechNet forums - Windows Server 2012 General - Microsoft

  Hope that helps

• Why the current value of the index cache is 0 MB?

  Everyone happy President's day!

  I ran calc scripts on a BSO cube. I checked EAS and data Cache hit ratio and Index is 0.

  I've already put key cache at 200 MB, but EE watch my current value hides index is 0 MB. Why?

  I already have data cache to 300 MB, but EE shows that my current value of the data cache is 0 MB. Why?

  I restarted my app BSO and db.

  Thank you.

  ORCLSendsMeToEarlyGrave wrote:

  Our test server is on Exalytics.  I wonder if this is why? All our BSO cubes have zero to Hit Ratio. Same Basic sample - after I ran Calc by default.

  If it is Exalytics that shows zero for Hit Ratio then read through a recent post that relates to this - Hit ratio

  See you soon

  John

• run to analyze the ratio is 49 any problem

  Hello
  
  run to analyze the ratio is 49 any problem?

  I guess that you are looking at a Statspack or AWR report?

  First, it is important to understand what is the Execute ratio analysis.

  It is calculated as:

  round(100*(1-:prse/:exe),2)
  

  So the idea is, for a given SQL statement, in an ideal world, analyze you once and run it several times. If you do this, your analysis Execute ratio will tend towards 100%. 100% is a "perfect score".

  You analyze more, compared to the executions, the ratio will fall. If you analyze once per run, your analysis Execute ratio will increase to 0%. It's not good, but it could actually be even worse than that. Some applications of brain dead actually do an analysis more than executions. If this happens, your analysis Execute ratio will be negative.

  Thus, the 49 is "bad"? What is bad? Well, it depends. While it is true that any analysis Execute ratio that is less than 90 could potentially be improved, the question really is how much that will benefit your system?

  So, you should ask yourself a few questions. First of all, you have even a probem performance? If not, then any effort spent tuning system is almost certainly a waste of time. If you do have a performance problem, you should be profiling critical, in order to analyse and understand business processes where they spend their time. If one or more, bad execution, critical business process spends too much time on the analysis, then it may be worth looking at what is happening.

  In general, such as Parse Execute, buffer cache hit ratios, etc., are almost never useful in isolation. However, if all you have is an AWR or Statspack report, and you try to understand if the ratio Execute analysis needs attention, then you should look at some other numbers in the report. Review the Top 5 timed events; If none of them have nothing to do with the analysis? If this isn't the case, then the analysis probably isn't a problem. Look at % of the Non-Parse CPU; If it is very high, said in the early 1990s, almost certainly analysis isn't a problem important, so who cares about the Parse Execute ratio?

  Finally, if you do think that, in your case, Execute ratio analysis is a problem, it is important to know that the only way to improve it is by reducing the number of analysis or to increase the number of executions. And, the only way to change the number of analysis or executions, by changing the client program. There is no instance level control or a parameter that will have an impact on this statistic.

  Hope that helps you understand how to interpret this statistic,

  -Mark

• Using the Cache monitoring

  Hello
  I was working a group of cache on certain tables.
  
  Is it possible to monitor the State of the cache (caching of data per hour and relationship between cache and database bed data, while progressing of time)?
  
  
  Thank you
  Fabio Alfonso

  I think it really depends on the type of RAM that you have configured. If you use 'static' caching (you have not used the word DYNAMICS when you set your cache groups) then:

  -Only the data that you have explicitly requested with LOAD/REFRESH CACHE GROUPS will be present in the cache tables for groups of AWT and SWT and USERMANAGED without AUTOREFRESH cache. For READONLY and USERMANAGED/AUTOREFRESH groups cache then only the data in the cache will be data which correspond to no matter WHERE clause specified in the definition of Group of cache. You can find out how many rows in a table of caching your any time using SELECT COUNT (*) FROM tablename.

  -Any given query or operation DML will run only in one place. that is, TimesTen or Oracle. Transactions are limited to one place (TimesTen or Oracle). There is therefore no concept of a "cache" for this kind of configuration and "cache hit ratio" is always 100% for applications that run in TimesTen.

  For groups of dynamics of the cache, for some types of query/DML, if there is no foiund in TimesTen, TimesTen will be try and retrieve data from Oracle, put it in the cache and return the result to the application. In this case:

  -You can find out how many rows in a table being cached at any time using SELECT COUNT (*) FROM tablename (since this type of operation do not dynamically extract data from Oracle and so the result reflects only the data of the TimesTen at that time).

  -You can watch more of the TimesTen SYS fields. Table of MONITOR (TPL_FETCHES, TPL_EXECS and CACHE_HITS) to get an idea of the effectiveness of the cache is to be.

  Hope that helps.

  Chris

• Data file Cache Vs I/O buffer

  Hello all-
  
  I lived chapter of parameters for the Ser60 cache and I have found that if my storage type is file cache settings buffered IO data is not used.
  
  I have a database that is buffering of i/o & RLE encoding and have the following cache settings:
  
  File data cache: 300000 (KB)
  Data cache: 37500 (KB)
  
  Can someone let me know if this database would be to use cache data files?
  
  If I decrease the cache of data files and increase the data cache would it effect application performance
  
  Thank you!

  If you look at the tab caches, you will see that none of your data files cache is used. in order to do no amtter what this number is.

  The cache setting affects how many blocks (uncompressed) that can enter the memory, so the encoding type has no effect on it, do not look at what data cache hit ratio in the statistics tab. If you get a low hit ratio, while you would like to consider to increase it. In addition, if you have a lot of dynamic calculations on the dense dimensions you want to increase as well.