Oracle database

  • Alternative Views of What Oracle Exadata Is

    What is the main purpose of the Oracle assignment ExadataWe have already finde a rather bland description of how it spec view Oracle Exadata. However, like the well-known tale of the blind men describing an elephant, there are many conflicting perceptions about the nature of Exadata. We will cover a few of the common descriptions in this blog note.

  • Basic Oracle Database 12c Security: Authentication

    aBasic Oracle Database 12c SecurityAuthentication is a very important process, whose purpose is to determine whether someone or something is, in fact, who or what it claims to be.

    In this chapter, you'll learn basic stuff about some of the different authentication methods supported by Oracle Database 12c. Also, a brief overview about creating and using database roles will be given.

    There are three new administrative privileges introduced in Oracle Database 12c (sysbackup, syskm, and sysdg). Their purpose is to enable better separation of duties and they are designed in such a way to also enable implementation of the least privilege principle. Although it may seem that implementation of this principle in systems is easy or straightforward, usually it's quite tricky.

  • Best Practices of Oracle Database with Real Application Clusters 12c High Availability

    Best Practices using of Oracle RAC 12c for Database High  AvailabilityApplying MAA Principles

    Begin with a business impact analysis

    1. Assess impact of downtime & data loss
    2. Define service level objectives
      • Recovery Time Objective (RTO):
        - How long can you afford to be down?
      • Recovery Point Objective (RPO):
        - How much data can you afford to lose?
      • Performance:
        - pre and post failure

    Oracle Database 12c MAA

  • Big Data Use Cases and NoSQL databases

    Big Data & NoSQL use casesThe initial use of NoSQL technology began with the social media sites as they were looking at ways to deal with large sets of data generated by their user communities. For example, in 2010 Twitter saw data arriving at the rates of 12TB/day, and that resulted in a 4PB dataset in a year. These numbers have grown significantly as Twitter usage has expanded globally.

  • Choosing a database for your application: MySQL, Oracle, SQL Server or DB2?

    How to Choosing a database for your application?All but the simplest application will connect to a database to store and retrieve data. Some applications utilize a proprietary database, but the majority will connect to one of the major commercially available relational database management systems. Oracle, Microsoft’s SQL Server, IBM DB2, and MySQL are some of the most commonly used database products.

    As the Application Administrator, you will want to know as much about the database as you can. Some of the details that you want to learn about are listed here.

  • Choosing Oracle Database 12c Table Features for Performance

    Oracle Database 12c Table Features for performanceProblem

    When creating tables, you want to implement the appropriate table features that maximize performance, scalability, and maintainability.

     

    Solution

    There are several performance and sustainability issues that you should consider when creating tables. Table 1 describes features specific to table performance.

     

  • Cloning Oracle Database 12c from Cold Backup

    Restoring Oracle Database from cold backupThis article will walk you through manual methods for cloning databases and tablespaces. If you’re already familiar with these techniques, then feel free to move on to the next chapters in this book, which illustrate how to employ the RMAN duplication process. 

    Knowledge of these methods will help you understand when it’s appropriate to use a technique and its advantages and disadvantages. This information will help you better understand the other chapters in this book that contrast these techniques with the RMAN DUPLICATE functionality. First up is cloning a database using a cold backup.

  • Creating new Oracle Database 12c with Maximum Performance

    Oracle Database 12c with Maximum Performance BUILDProblem

    You realize when initially creating a database that some features (when enabled) have long-lasting implications for table performance and availability. Specifically, when creating the database, you want to do the following:

    • Enforce that every tablespace ever created in the database must be locally managed. Locally managed tablespaces deliver better performance than the obsolete dictionary-managed technology.
    • Ensure users are automatically assigned a default permanent tablespace. This guarantees that when users are created they are assigned a default tablespace other than SYSTEM. With the deferred segment feature (more on this later), if a user has the CREATE TABLE privilege, then it is possible for that user to create objects in the SYSTEM tablespace even without having a space quota on the SYSTEM tablespace. This is undesirable. It’s true they won’t be able to insert data into tables without appropriate space quotas, but they can create objects, and thus inadvertently clutter up the SYSTEM tablespace.
    • Ensure users are automatically assigned a default temporary tablespace. This guarantees that when users are created they are assigned the correct temporary tablespace when no default is explicitly provided.
  • Creating Oracle 12c Tablespaces to Maximize Performance

    Creating Oracle 12c Tablespaces with Max PerformanceProblem

    You realize that tablespaces are the logical containers for database objects such as tables and indexes. Furthermore, you’re aware that if you don’t specify storage attributes when creating objects, then the tables and indexes automatically inherit the storage characteristics of the tablespaces (that the tables and indexes are created within). Therefore you want to create tablespaces in a manner that maximizes table performance and maintainability.

  • Creating password-authenticated users in Oracle 12c

    Creating password user in Oracle 12cIn this task, you will create several users. To complete this recipe, you'll need an existing user who has create user privilege (you may use the OS-authenticated user who has the DBA role).

    You'll use Oracle Enterprise Manager Database Express 12c (EM Express). To learn more about it (for example, how to configure an HTTPS port for EM Express and how to start it), see the third chapter of the official Oracle guide -Oracle Database 2 Day DBA, 12c Release 1.

  • Creating powerful application with Oracle Database

    Application creation with OracleFor an Oracle application to be built and used rapidly and effectively, users and developers must share a common language and a deep and common understanding of both the business application and the Oracle tools. This is a new approach to development. Historically, the systems analyst studied the business requirements and built an application to meet those needs. The user was involved only in describing the business and, perhaps, in reviewing the functionality of the application after it was completed.

  • Getting Started with Oracle and PL/SQL programming

    How to start coding on PL/SQL for Oracle Databases for novices?In this lesson, you’ll learn what Oracle and PL/SQL are, and what tools you can use to work with them.

    What Is Oracle?

    In the previous lesson, you learned about databases and SQL. As explained, it is the database software (DBMS or Database Management System) that actually does all the work of storing, retrieving, managing, and manipulating data. Oracle DBMS (or just “Oracle”) is a DBMS; that is, it is database software.

  • Getting Started with Oracle Database 12c Release 2

    Getting first steps with Oracle Database 12c Release 2: preinstallWelcome to Oracle Database 12c Release 2 New Features blog, covering Oracle’s latest release. I’ve done my best to provide as much coverage of the many new features in Oracle Database 12c Release 2 as fits in a blog of this size. Oracle Database 12c Release 1 was a big release with a number of new and changed features. Oracle Database 12c Release 2 adds many more features and enhances all of the new ones introduced in Release 1!

    This first my blog article describes everything you need to know to get started with Oracle Database 12c Release 2. This includes the following topics:

  • Handling GC Buffer Busy Wait Events in Oracle 12c with ORAchk Utility

    GC Buffer Busy Wait Events in Oracle 12c & ORAchk UtilityOracle Database 12c is the most complete and simultaneously complex database in today’s database marketplace. Every time Oracle launches a new release, a lot of new features are made available, and anyone who works as an Oracle database administrator (DBA) knows how difficult it is to stay current on all feature sets. It is entirely possible that an Oracle DBA may be required to manage multiple databases that are running on completely different releases of Oracle. To add to this complexity, each database may have several distinct features enabled, including various versions of table and index partitioning, Oracle Advanced Compression, replication between databases using either Oracle Streams or Oracle GoldenGate, Oracle Real Application Clusters (RAC), and many others. A RAC database is one of the most difficult environments to administer because its different architecture exists mainly to offer high availability for database applications. This article therefore focuses on the global cache (gc) buffer busy wait event, one of the most commonly encountered wait events in a RAC database.

  • How to ensure the Oracle database security?

    Database security has several aspects. First, there is authentication: Who can connect? How does one identify them? Second, there is authorization: What are users allowed to do? How does one restrict their actions? Finally, there is auditing: Given that users can connect and perform certain actions, how do you track what they are doing? These aspects are covered in this short note.

  • How to view Oracle database processes running on the Linux server?

    Problem

    You want to view processes currently running on the Oracle database server (Linux / Solaris).

    Solution

    To view process information, use the ps (process status) utility. If you type the ps command without any parameters, you see all processes that have been started by the user you’re currently logged on as:

  • Isolating GC Buffer Busy Waits in Oracle Database 12c

    Isolating GC Buffer Busy Waits in OracleThe three key tools that every Oracle DBA who has worked on a database since Oracle 10g should know about - Automatic Database Diagnostic Monitor (ADDM), Automatic Workload Repository (AWR) reports, and Active Session History (ASH) reports - are also extremely useful for detecting performance issues related to the gc buffer busy wait event. The next sections explain exactly how to locate crucial information about the statements, user sessions, and database objects that are causing an Oracle database to perform poorly because of high occurrences of the gc buffer busy wait event.

  • Issues with DTP, XA and Rollback Segments in an Oracle Database

    Issues with DTP, XA and Rollback Segments in OracleOracle Database applications that connect to multiple databases via database links or that use XA (extended Architecture) for distributed transaction processing (DTP) may occasionally experience issues with pending transactions. When such issues arise, it’s not unusual to encounter extreme contention, often to the point that the database instance “hangs,” which may cause all database DML operations to halt until the problem is resolved. The following checklist and corresponding scripts will help to ascertain if an Oracle database instance is in danger of hanging due to issues with DTP via XA:

  • Matching Oracle 12c Table Types to Business Requirements

    Selecting Oracle 12c Table TypesProblem

    You’re new to Oracle Database 12c and have read about the various table types available. For example, you can choose between heap-organized tables, index-organized tables, and so forth. You want to build a database application and need to decide which table type to use.

    Solution

    Oracle provides a wide variety of table types. The default table type is heap-organized. For most applications, a heap-organized table is an effective structure for storing and retrieving data. However, there are other table types that you should be aware of, and you should know the situations under which each table type should be implemented. Table 1 describes each table type and its appropriate use.

  • Oracle 12c: a New Cloud Consolidation Era in IT

    Oracle database 12c Cloud Consolidation capabilitiesLet’s start by taking a brief look at the history of database use, before introducing the architecture of the future. As you can see in Figure 1-1, we will not refer to dates, but version numbers, going back to the time when the Oracle Database became predominant. 

    When Oracle Database 8i and 9i were on the market, midrange computers became prevalent in data centers. We were moving from the mainframe era to a client/server era, and Oracle architecture was very well suited for that. Written in the C programming language, it was available on multiple platforms and with all user management contained within its data dictionary. It was ready for the client/server architecture, using the OS only to listen on a TCP/IP port and to store files. Furthermore, the architecture was scalable on minicomputers, thanks to the parallel server feature, which would later become RAC (Real Application Clusters).

     

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