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Dariusz Owczarek

Oracle ASSM Performance - 0 views

www.dba-oracle.com/...t_assm_performance.htm

dba oracle performance edba

shared by Dariusz Owczarek on 13 Sep 10 - No Cached
  • Cons of ASSM: §         Slow for full-table scans: Several studies have shown that large-table full-table scans (FTS) will run longer with ASSM than standard bitmaps. ASSM FTS tablespaces are consistently slower than freelist FTS operations. This implies that ASSM may not be appropriate for decision support systems and warehouse applications unless partitioning is used with Oracle Parallel Query. §        Slower for high-volume concurrent inserts: Numerous experts have conducted studies that show that tables with high volume bulk loads perform faster with traditional multiple freelists. §         ASSM will influence index clustering: For row ordered tables, ASSM can adversely affect the clustering_factor for indexes. Bitmap freelists are less likely to place adjacent tows on physically adjacent data blocks, and this can lower the clustering_factor and the cost-based optimizer's propensity to favor an index range scan.
  • Pros of ASSM: §          Varying row sizes: ASSM is better than a static pctused. The bitmaps make ASSM tablespaces better at handling rows with wide variations in row length. §         Reducing buffer busy waits: ASSM will remove buffer busy waits better than using multiple freelists. When a table has multiple freelists, all purges must be parallelized to reload the freelists evenly, and ASSM has no such limitation. §         Great for Real Application Clusters: The bitmap freelists remove the need to define multiple freelists groups for RAC and provide overall improved freelist management over traditional freelists.
  • Cons of ASSM: §         Slow for full-table scans: Several studies have shown that large-table full-table scans (FTS) will run longer with ASSM than standard bitmaps. ASSM FTS tablespaces are consistently slower than freelist FTS operations. This implies that ASSM may not be appropriate for decision support systems and warehouse applications unless partitioning is used with Oracle Parallel Query. §          Slower for high-volume concurrent inserts: Numerous experts have conducted studies that show that tables with high volume bulk loads perform faster with traditional multiple freelists. §          ASSM will influence index clustering: For row ordered tables, ASSM can adversely affect the clustering_factor for indexes. Bitmap freelists are less likely to place adjacent tows on physically adjacent data blocks, and this can lower the clustering_factor and the cost-based optimizer's propensity to favor an index range scan.
  • Dariusz Owczarek on 13 Sep 10
     
    Oracle ASSM Performance pros and cons
Dariusz Owczarek

Oracle's V$ Views - Dynamic Performance Views - 1 views

www.adp-gmbh.ch/...dynamic_performance_views.html

dba oracle v$ dictionary

shared by Dariusz Owczarek on 27 Jun 09 - Cached
  • v$database This view lets you access database information.
  • v$datafile This view contains an entry for each datafile of the database.
  • v$dataguard_status Shows error messages in a data guard environment.
  • ...11 more annotations...
  • v$flash_recovery_area_usage See also v$recovery_file_dest
  • v$lock This view stores all information relating to locks in the database.
  • v$mystat This view records statistical data about the session that accesses it.
  • v$parameter Lists the name-value pairs of the init.ora file (or their default, if not in the init.ora).
  • v$session
  • v$session_longops Use v$session_longops if you have a long running pl/sql procedure and want to give feedback on how far the procedure proceeded.
  • v$session_wait This views shows what wait event each session is waiting for, or what the last event was that it waited for.
  • v$session_wait_history This view is new in Oracle 10g and allows improved timing and statistics.
  • v$sqlarea Join v$sqlarea's address with v$session's sql_address.
  • v$sql_bind_capture New with Oracle 10g This view captures bind variables for all sessions and is faster than setting 10046 on level 4.
  • v$version Use this view to find out what version you actually work on: select * from v$version;
  • Dariusz Owczarek on 27 Jun 09
     
    Oracle's data dictionary provides information that Oracle needs to perform its tasks. The data dictionary is stored in table structures owned by SYS. Their content is exposed through dictionary views. Dynamic performance views (so called v$ views) are part of Oracle's data dictionary.
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.
  • ...3 more annotations...
  • 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

Oracle GoldenGate Best Practices and Tips - 0 views

decipherllc.blogspot.com/...engate-best-practices-and.html

oracle goldengate

shared by Dariusz Owczarek on 24 Feb 11 - No Cached
  • PARALLEL PROCESSING Ensure the system has enough shared memory. GoldenGate runs as an Oracle process. Each Extract or Replicat process requires upwards of 25-50 MB of system shared memory. This means less memory for the Oracle DBMS, especially the SGA. Use parallel Replicat groups on the target system to reduce latency thru parallelism. Consider parallel Extract groups for tables that are fetch intensive (e.g., those that trigger SQL procedures). Group tables that have R.I. to each other in the same Extract-Replicat pair. Pair each Replicat with its own trail and corresponding Extract process. When using parallel Replicats, configure each one to process a different portion of the overall data.
  • PASSTHRU PARAMETER Consider using this parameter if there is no filtering, conversion or mapping required and you’re using DATAPUMP. In pass-through mode, the Extract process does not look up table definitions, either from the database or from a data definitions file. Pass-through mode increases the throughput of the data pump, because all of the functionality that looks up object definitions is bypassed. This saves database fetches to improve performance.
  • INSERTAPPEND A new GoldenGate 10.4 feature. Use for large transactions . Puts records at end of table rather than doing a more costly insert into other areas of table.
  • ...6 more annotations...
  • To reduce bandwidth requirements: Use compression options of the RMTHOST parameter to compress data before it is sent across the network. Weigh the benefits of compression against the CPU resources that are required to perform the compression.
  • To increase the TCP/IP packet size: Use the TCPBUFSIZE option of the RMTHOST parameter to increase the size of the TCP socket buffer that Extract maintains. By increasing the size of the buffer, you can send larger packets to the target system. Consult with Network Support before setting TCPBUFSIZE.
  • Use SQL Arrays The BATCHSQL parameter will increase the performance of Replicat. BATCHSQL causes Replicat to create arrays for similar SQL statements and apply them at an accelerated rate. Normally, Replicat applies one SQL statement at a time.
  • Use the CHECKPOINTSECS in Extract or Replicat; if increased, less frequent checkpoints; increases data to be reprocessed if process fails; keep transaction logs available in case of reprocessing
  • Use the GROUPTRANSOPS; increases number of SQL operations in a Replicat ; reduces I/O to checkpoint file and checkpoint table.
  • Data Filtering and Conversion: Use primary Extract for data capture only. Use a data pump on the source to perform filtering and thereby send less data over the network. Alternatively, use Replicat for conversion and, if the network can handle large amounts of data, also for filtering.
  • Dariusz Owczarek on 24 Feb 11
     
    Oracle GoldenGate Best Practices and Tips
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.
Dariusz Owczarek

lsnrctl Tracing Oracle Listener Connections - 0 views

www.praetoriate.com/teas_prae_util25.htm

dba oracle

shared by Dariusz Owczarek on 28 Aug 09 - Cached
  • LSNRCTL> set trc_level ADMIN
  • Format Trace File with the trcasst utility
  • Dariusz Owczarek on 28 Aug 09
     
    Network connections can be traced to provide a detailed description of the operations performed by Oracle's internal components. The trace data is stored in an output trace file that can then be analyzed.
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...
donaldjmarshal

Zero Cost Cloud Migration Services | Migration Of Workloads to Cloud | Suneratech - 0 views

www.suneratech.com/...zero-cost-cloud-migration

Zero cost Migration services Of Workloads to Cloud

shared by donaldjmarshal on 27 Mar 20 - No Cached
  • donaldjmarshal on 27 Mar 20
     
    Zero Cost Cloud Migration CLOUD-FIRST is a captivating concept around which the emerging businesses are predominantly dependent upon. While it aligns with the digital transformation strategies built for enterprises, migrating workloads to cloud comes with its own challenges like flexibility, application performance and budgets. more details visit Zero cost cloud Migration services In a data-driven world, you need a comprehensive business model to accelerate your IT transformation with cloud services and offering you the advantages of a cloud. Suneratech improves your business agility, security, cost-efficiency, and simplicity, with a 4-step strategy to move you to cloud while reaping the benefits. ZCCM Advantage for Customers When a customer withdraws from other service providers like IBM or OMCS, and opt for a new provider, a customer must pay for both the providers until the migration is completed. ZCCM program is a great choice for such customers, as it saves this double cost by paying all the Oracle costs until the customer's contract terminates with other cloud service providers. Suneratech migrates all workloads in scope to Oracle Cloud Infrastructure (OCI), at ZERO Cost, and will not invoice until all workloads are successfully migrated to Cloud.
Dariusz Owczarek

GC Buffer Busy Waits in RAC: Finding Hot Blocks - 0 views

www.ardentperf.com/...aits-in-rac-finding-hot-blocks

dba oracle performance rac gc

shared by Dariusz Owczarek on 19 Jul 10 - Cached
  • Here’s a handy little query I made up the other day to quickly digest any of the segment statistics from the AWR and grab the top objects for the cluster, reporting on each instance.
  • Any time you see heavy concurrency problems during inserts on table data blocks there should always be one first place to look: space management. Since ancient versions of OPS it has been a well-known fact that freelists are the enemy of concurrency.
  • Dariusz Owczarek on 19 Jul 10
     
    GC Buffer Busy Waits in RAC: Finding Hot Blocks
Dariusz Owczarek

collectl system monitoring tool - 0 views

collectl.sourceforge.net/index.html

dba unix performance

shared by Dariusz Owczarek on 25 Jun 09 - Cached
  • Dariusz Owczarek on 25 Jun 09
     
    Unlike most monitoring tools that either focus on a small set of statistics, format their output in only one way, run either interatively or as a daemon but not both, collectl tries to do it all. You can choose to monitor any of a broad set of subsystems which currently include buddyinfo, cpu, disk, inodes, infiniband, lustre, memory, network, nfs, processes, quadrics, slabs, sockets and tcp.
Dariusz Owczarek

Oracle announces availability of Oracle Database 11g Release 2 - 0 views

www.oracledatabase11g.com/...NewsEvents_w.html

dba oracle

shared by Dariusz Owczarek on 10 Sep 09 - Cached
  • In this release, Edition-based Redefinition is introduced to allow customer database applications to be upgraded online; this removes the need for separate upgrade environments.
  • This release also delivers enhanced query performance with the ability to transparently execute a query against data stored in memory across all the servers in a grid.
  • In this release, Oracle Automatic Storage Management is extended to support a general-purpose cluster file system to help customers reduce their storage management costs.
  • ...1 more annotation...
  • The combination of Oracle Database 11g Release 2 Advanced Compression and Partitioning support the reduction of storage costs by compressing data as much as 2-4x and simplifying use of lower cost storage tiers.
Dariusz Owczarek

Configuration of TAF (Transparent Application Failover) and Load Balancing - 0 views

metalink.oracle.com/...flash.html

dba oracle development

shared by Dariusz Owczarek on 02 Oct 09 - Cached
  • The client load balancing feature enables clients to randomize connection requests among the listeners. Tnsnames Parameter: LOAD_BALANCE
  • The connect-time failover enables clients to connect to another listener if the initial connection to the first listener fails. The number of listener protocol addresses determines how many listeners are tried. Without connect-time failover, Oracle Net attempts a connection with only one listener. The default is on. Tnsnames Parameter: FAILOVER
  • The listener connection load balancing feature improves connection performance by balancing the number of active connections among multiple dispatchers and instances. In a single-instance environment, the listener selects the least loaded dispatcher to handle the incoming client requests. In an Oracle Real Application Clusters (RAC) environment, connection load balancing also has the capability to balance the number of active connections among multiple instances. 1. Least-loaded node 2. Least-loaded instance 3. Least-loaded dispatcher for that instance (in case of Shared server configuration)
  • ...2 more annotations...
  • Transparent Application Failover (TAF) is a feature of the Oracle Call Interface (OCI) driver at client side. It enables the application to automatically reconnect to a database, if the database instance to which the connection is made fails. In this case, the active transactions roll back. Tnsnames Parameter: FAILOVER_MODE
  • Doc ID: 453293.1
  • Dariusz Owczarek on 02 Oct 09
     
    This note explains the configuration in 10g & 11g for: Client Side Connect Time Load Balance; Client Side Connect Time Failover; Server Side Listener; Connection Load Balance; Transparent Application Failover (TAF)
Dariusz Owczarek

Call a stored procedure over a database link - 1 views

asktom.oracle.com/...f

dba oracle pl_sql

shared by Dariusz Owczarek on 16 Dec 10 - No Cached
  • In a distribute transaction -- one in which "DATABASE A" calls "DATABASE B", only "DATABASE A" may commit -- the reason -- "database B" has no mechanism for co-ordinating with "database a" on the commit. We need to do a 2 phase commit to ensure that when the transaction commits any work performed on DATABASE A is committed *as well as* any work on database b.
  • This is the reason will do no allow for ANY node other then the "parent" node of the transaction to issue a commit or rollback in a distributed transaction. The other nodes simply do not have control over the other possible nodes in the transaction.
  • Dariusz Owczarek on 16 Dec 10
     
    Call a stored procedure over a database link
Dariusz Owczarek

Oracle Database Health Recommendations Catalog - 0 views

metalink2.oracle.com/...f

dba oracle

shared by Dariusz Owczarek on 04 Nov 09 - Cached
  • Oracle Database Availability Configure Install Patching Performance Security
  • Enterprise Manager Configure Patching
  • Dariusz Owczarek on 04 Nov 09
     
    This catalog contains a complete list of all health recommendations available in My Oracle Support.
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