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Ruud Schilders

ORACLE-BASE - Oracle DBA and development articles, scripts, HOWTOs and forums (8i, 9i, ... - 0 views

www.oracle-base.com

oracle manuals reference howto

shared by Ruud Schilders on 30 Jul 09 - Cached
  • Ruud Schilders on 30 Jul 09
     
    Contains easy step-by-step manuals for installing Oracle on Linux, vmware etc.
Dariusz Owczarek

Oracle Diagnostic Tools - 0 views

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

dba edba oracle

shared by Dariusz Owczarek on 04 Jun 10 - Cached
  • Enterprise Manager A graphical all-purpose tool that can be used to identify when a spike occurred, drill down to the cause, and examine ADDM recommendations. The benefit of a graphical representation of performance data is visible (pun intended). Data visualizations display any skew directly.
  • Automatic Database Diagnostic Monitor (ADDM) An expert system that automatically identifies and recommends solutions for many instance-wide performance problems. Best used for longer-duration performance problems (that is, problems that are continuous or ongoing for a large proportion of the snapshot interval). The symptoms and problems are available by running the ADDM report, and through Enterprise Manager.
  • Active Session History (ASH) An all-purpose tool providing data that is useful when investigating system-wide problems, shorter-duration spikes, or smaller-scoped problems (for example, for a specific user, or SQL, or a module/action).The advantage of using ASH data when compared to other diagnostic information is that the data is of a finer granularity. This allows you to look at a problem to identify how the symptoms "build up," or allows you to determine exactly which resources are involved and who is using them. The ASH data can be queried directly or accessed via a targeted ASH report.
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  • Automatic Workload Repository (AWR) Instance-wide summary data that is used when ADDM is not able to identify the problem in the system, and the problem is of longer duration. Also used to verify the ADDM analysis. The data can be queried directly but is most often accessed via the AWR instance report.
  • Statspack (SP) Instance-wide summary data used to manually diagnose performance problems. You should use SP when you are not licensed for the Diagnostics Pack, and so can't use ADDM or AWR.
  • SQL trace This traces the execution flow (resource utilization, execution plan, and waits) by SQL statement. The information can be used to examine the flow and resource utilization for a specific user, feature, or SQL statement identified as problematic.
Dariusz Owczarek

Hash partitioning - 0 views

asktom.oracle.com/...f

dba oracle partitioning

shared by Dariusz Owczarek on 09 Mar 11 - No Cached
  • - instead of having a 100 gig tablespace to backup, you have 100, 1 gig tablespaces. (each tablespace spends less time in backup mode, reduces the amount of potential extra redo, reduces the amount of manual recovery you need to do if the instance failes during backup). same with restores.
  • every single admin option you do to a partition applies to a hash partition
  • Say you do a join on the hash partition key -- we can do parallel partition wise elimination on the join
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  • Hash partitioning -- all of admin features of range partitions and many of the partition elimination/query features as well.
  • With a harsh partition, we are attempting to achieve an EVEN distribution of data across all of the partitions while at the same time supporting partition elimination and other features.
  • you want an ALMOST unique or unique value to hash on
  • with hashing -- all rows with the same key by definition hash to the same partition -- that is the very essence of hash partitioning
  • you would just drop/truncate the oldest partition and if you do this with the option to maintain the indexes, it'll not impose any sort of rebuild
  • with hash partitions, you want to hash on something that is almost unique (or at least has lots of values) and into powers of 2 you want 2, 4, 8, 16, 32, 64, 128, .... partitions. 50 is not going to work (you'll always get a bell shape with the partitions at the front and end having the least and the ones in the middle having the most)
  • Dariusz Owczarek on 09 Mar 11
     
    Hash partitioning
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