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Dariusz Owczarek

A UML Profile for Data Modeling - 0 views

www.agiledata.org/...umlDataModelingProfile.html

dba edba uml modeling

shared by Dariusz Owczarek on 19 Jul 10 - Cached
  • Unfortunately data modeling is not yet covered by the Unified Modeling Language (UML), even though persistence-related issues are clearly an important aspect of object-oriented software project.
  • The good news is that the Object Management Group (OMG) issued an RFP for an official UML Data Modeling Profile in December 2005.
  • This page summarizes the data modeling profile for UML Class Diagrams, that I apply in Agile Database Techniques, The Object Primer 3rd Edition, and Refactoring Databases.  First some important definitions:
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  • Logical data models (LDMs).  LDMs are used to explore either the conceptual design of a database or the detailed data architecture of your enterprise.  LDMs depict the logical data entities, typically referred to simply as data entities, the data attributes describing those entities, and the relationships between the entities.
  • Physical data models (PDMs).  PDMs are used to design the internal schema of a database, depicting the data tables, the data columns of those tables, and the relationships between the tables.
  • Conceptual data models.  These models are typically used to explore domain concepts with project stakeholders.  Conceptual data models are often created as the precursor to LDMs or as alternatives to LDMs.
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).
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  • 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.
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.
donaldjmarshal

Live Webinar on Revolutionise IT support with Conversational AI | Suneratech - 0 views

www.suneratech.com/...support-with-conversational-ai

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shared by donaldjmarshal on 16 Mar 20 - No Cached
  • donaldjmarshal on 16 Mar 20
     
    #Webinar | Make your ITSM Delivery less complex, more efficient and cost-effective with conversational AI. Join us for an interactive session and learn how pro-active engagement model of #conversationalai driven automation can be a game changer in your IT support processes Book your seat here: https://bit.ly/3aJLvJw
Dariusz Owczarek

SQL SELECT Syntax - 0 views

download.oracle.com/...statements_10002.htm

dba oracle sql

shared by Dariusz Owczarek on 12 Jun 09 - Cached
  • Dariusz Owczarek on 12 Jun 09
     
    SQL SELECT statement or subquery is used to retrieve data from one or more tables, object tables, views, object views, or materialized views.
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