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Oracle Optimization - Table Partitions
 
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Oracle optimization: create table partitions and Index-Organized Table. Other lessons, visit http://www.learn-with-video-tutorials.com/plsql-oracle-optimization
Index Organized Tables and Examples
 
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Index Organized Tables and Examples watch more videos at https://www.tutorialspoint.com/videotutorials/index.htm Lecture By: Mr. Parth Panjab, Tutorials Point India Private Limited
01 Overview of table Partition in oracle
 
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Partitioning enhances the performance, manageability, and availability of a wide variety of applications and helps reduce the total cost of ownership for storing large amounts of data. Partitioning allows tables, indexes, and index-organized tables to be subdivided into smaller pieces, enabling these database objects to be managed and accessed at a finer level of granularity. Oracle provides a rich variety of partitioning strategies and extensions to address every business requirement. Moreover, since it is entirely transparent, partitioning can be applied to almost any application without the need for potentially expensive and time consuming application changes. Partitioning allows a table, index, or index-organized table to be subdivided into smaller pieces, where each piece of such a database object is called a partition. Each partition has its own name, and may optionally have its own storage characteristics. From the perspective of a database administrator, a partitioned object has multiple pieces that can be managed either collectively or individually. This gives the administrator considerable flexibility in managing partitioned objects. However, from the perspective of the application, a partitioned table is identical to a non-partitioned table; no modifications are necessary when accessing a partitioned table using SQL queries and DML statements. Partitioning Key ======================== Each row in a partitioned table is unambiguously assigned to a single partition. The partitioning key is comprised of one or more columns that determine the partition where each row will be stored. Oracle automatically directs insert, update, and delete operations to the appropriate partition through the use of the partitioning key. When to Partition a Table ========================== Here are some suggestions for when to partition a table: Tables greater than 2 GB should always be considered as candidates for partitioning. Tables containing historical data, in which new data is added into the newest partition. A typical example is a historical table where only the current month's data is updatable and the other 11 months are read only. When the contents of a table need to be distributed across different types of storage devices. When to Partition an Index ============================= Here are some suggestions for when to consider partitioning an index: Avoid rebuilding the entire index when data is removed. Perform maintenance on parts of the data without invalidating the entire index. Reduce the impact of index skew caused by an index on a column with a monotonically increasing value. Partitioned Index-Organized Tables =================================== Partitioned index-organized tables are very useful for providing improved performance, manageability, and availability for index-organized tables. For partitioning an index-organized table: ============================================ Partition columns must be a subset of the primary key columns Secondary indexes can be partitioned (both locally and globally) OVERFLOW data segments are always equi-partitioned with the table partitions See Also: Oracle Database Concepts for more information about index-organized tables System Partitioning System partitioning enables application-controlled partitioning without having the database controlling the data placement. The database simply provides the ability to break down a table into partitions without knowing what the individual partitions are going to be used for. All aspects of partitioning have to be controlled by the application. For example, an insertion into a system partitioned table without the explicit specification of a partition will fail. System partitioning provides the well-known benefits of partitioning (scalability, availability, and manageability), but the partitioning and actual data placement are controlled by the application. See Also: Oracle Database Data Cartridge Developer's Guide for more information about system partitioning Partitioning for Information Lifecycle Management Information Lifecycle Management (ILM) is concerned with managing data during its lifetime. Partitioning plays a key role in ILM because it enables groups of data (that is, partitions) to be distributed across different types of storage devices and managed individually.
Views: 6715 OnLinE ReSoUrCe
Oracle ||  Index Organized Tables by siva
 
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DURGASOFT is INDIA's No.1 Software Training Center offers online training on various technologies like JAVA, .NET , ANDROID,HADOOP,TESTING TOOLS , ADF, INFORMATICA,TABLEAU,IPHONE,OBIEE,ANJULAR JS, SAP... courses from Hyderabad & Bangalore -India with Real Time Experts. Mail us your requirements to [email protected] so that our Supporting Team will arrange Demo Sessions. Ph:Call +91-8885252627,+91-7207212428,+91-7207212427,+91-8096969696. http://durgasoft.com http://durgasoftonlinetraining.com https://www.facebook.com/durgasoftware http://durgajobs.com https://www.facebook.com/durgajobsinfo............
Local Vs Global Partitioned Index in Oracle 11g
 
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The Video Explains the difference between Local Partitioned Indexes(Prefixed vs Non Prefixed Indexes). and Global Partitioned Index along with the challenges in maintaining Global partitioned Indexes when the underlying tables partitioned is dropped/truncated/Merged/Moved. Local Partitioned Index Shares the same boundaries as the table and are in the same number as table partitions they are widely used in DSS and DWH systems. While Global Partitioned Index are predominantly used in OLTP systems
Views: 4734 Tech Coach
Oracle Tutorial || Online Training || Adv Sql | Index Organized Table Part - 1 by basha
 
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DURGASOFT is INDIA's No.1 Software Training Center offers online training on various technologies like JAVA, .NET , ANDROID,HADOOP,TESTING TOOLS ,ADF,INFORMATICA,TABLEAU,IPHONE,OBIEE,ANJULAR JS, SAP... courses from Hyderabad & Bangalore -India with Real Time Experts. Mail us your requirements to [email protected] so that our Supporting Team will arrange Demo Sessions. Ph:Call +91-8885252627,+91-7207212428,+91-7207212427,+91-8096969696. http://durgasoft.com http://durgasoftonlinetraining.com https://www.facebook.com/durgasoftware http://durgajobs.com https://www.facebook.com/durgajobsinfo......
Heap Tables and Index Organized Tables in Oracle | Chris Saxon
 
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Chris Saxon, a database evangelist, developer advocate, and SQL specialist with Oracle, uses up his two minutes with a tip on using heap tables and index organized tables in Oracle Database.
Partitioning in Oracle - Performance Basics
 
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This is the 2nd video from " Partitioning in Oracle " series, It explains how oracle stores and manages data. What is single Block IO and Multi Block IO ? Why full table scan is better than index access in few cases. The video is very elaborate, I have tried my level best to keep it as simple as possible
Views: 7581 Tech Coach
Index organised tables and heap tables, creating index organised tables
 
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Index organised tables and heap tables, creating index organised tables For Students of B.Tech, B.E, MCA, BCA, B.Sc., M.Sc., Courses - As Per IP University Syllabus and Other Engineering Courses
Oracle Tutorial || Oracle|Adv Sql | Partitioned Table Part - 1 by basha
 
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DURGASOFT is INDIA's No.1 Software Training Center offers online training on various technologies like JAVA, .NET , ANDROID,HADOOP,TESTING TOOLS ,ADF,INFORMATICA,TABLEAU,IPHONE,OBIEE,ANJULAR JS, SAP... courses from Hyderabad & Bangalore -India with Real Time Experts. Mail us your requirements to [email protected] so that our Supporting Team will arrange Demo Sessions. Ph:Call +91-8885252627,+91-7207212428,+91-7207212427,+91-8096969696. http://durgasoft.com http://durgasoftonlinetraining.com https://www.facebook.com/durgasoftware http://durgajobs.com https://www.facebook.com/durgajobsinfo.......
Types of Indexes (A B-tree index,A bitmap index )
 
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Hi guys today is very most important topic in oracle is INDEXES help to increase performance at the time of search and modification into table records. #TypesofIndexes #B-treeindex#bitmapindex
Views: 27269 Oracle World
Oracle Tutorial |Online Training ||Adv Sql | Index Organized Table Part - 3 by basha
 
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DURGASOFT is INDIA's No.1 Software Training Center offers online training on various technologies like JAVA, .NET , ANDROID,HADOOP,TESTING TOOLS ,ADF,INFORMATICA,TABLEAU,IPHONE,OBIEE,ANJULAR JS, SAP... courses from Hyderabad & Bangalore -India with Real Time Experts. Mail us your requirements to [email protected] so that our Supporting Team will arrange Demo Sessions. Ph:Call +91-8885252627,+91-7207212428,+91-7207212427,+91-8096969696. http://durgasoft.com http://durgasoftonlinetraining.com https://www.facebook.com/durgasoftware http://durgajobs.com https://www.facebook.com/durgajobsinfo......
Hash Partition in Oracle
 
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This course has been designed to impart the in-depth knowledge about the partitioning types and architecture in the Oracle RDBMS. For more information on this course, please visit https://www.koenig-solutions.com/oracle-database-12-c-implement-partitioning-training.aspx
Views: 52 Koenig Solutions
06 How to configure Sub partition using Rang & Hash in oracle
 
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You can create subpartitions in a composite partitioned table using a subpartition template. A subpartition template simplifies the specification of subpartitions by not requiring that a subpartition descriptor be specified for every partition in the table. Instead, you describe subpartitions only once in a template, then apply that subpartition template to every partition in the table. For interval-* composite partitioned tables, the subpartition template is the only way to define subpartitions for interval partitions. The subpartition template is used whenever a subpartition descriptor is not specified for a partition. If a subpartition descriptor is specified, then it is used instead of the subpartition template for that partition. If no subpartition template is specified, and no subpartition descriptor is supplied for a partition, then a single default subpartition is created. Specifying a Subpartition Template for a *-Hash Partitioned Table In the case of [range | interval | list]-hash partitioned tables, the subpartition template can describe the subpartitions in detail, or it can specify just the number of hash subpartitions. The following example creates a range-hash partitioned table using a subpartition template: CREATE TABLE emp_sub_template (deptno NUMBER, empname VARCHAR(32), grade NUMBER) PARTITION BY RANGE(deptno) SUBPARTITION BY HASH(empname) SUBPARTITION TEMPLATE (SUBPARTITION a TABLESPACE ts1, SUBPARTITION b TABLESPACE ts2, SUBPARTITION c TABLESPACE ts3, SUBPARTITION d TABLESPACE ts4 ) (PARTITION p1 VALUES LESS THAN (1000), PARTITION p2 VALUES LESS THAN (2000), PARTITION p3 VALUES LESS THAN (MAXVALUE) ); This example produces the following table description: Every partition has four subpartitions as described in the subpartition template. Each subpartition has a tablespace specified. It is required that if a tablespace is specified for one subpartition in a subpartition template, then one must be specified for all. The names of the subpartitions, unless you use interval-* subpartitioning, are generated by concatenating the partition name with the subpartition name in the form:
Views: 275 OnLinE ReSoUrCe
Indexes in Oracle :Index Scan Methods :Part 2
 
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The Video Explains when should you create indexes. The difference between Simple and composite Index, Relevance of order in composite indexes and Index Scan Methods in detail. 1.Index Unique scan 2.Index Range Scan 3. Index Skip Scan 4. Fast full Index Scan 5. Full Index Scan If you have any questions just drop in a comment
Views: 5274 Tech Coach
Oracle Query Optimization. Partitioned Tables and Indexes
 
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In this lesson, an introduction about Oracle Query Optimization. Partitioned Tables and Indexes. How to see plan of query. Monitoring plan of queries. SQL Plan
Views: 33 Mkrtich Pudeyan
How to Move Object from one Table Space to Another Table Space? | How to Rebuild the Index ?
 
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This Video will teach you How to Move Object one Table Space to Another | How to Rebuild the Index ? move table from one tablespace to another in oracle 11g oracle move schema to another tablespace oracle how to move objects to another tablespace oracle 11g move schema to another tablespace alter table move tablespace oracle 8i oracle move table script oracle move cluster to new tablespace oracle move table example rebuild index oracle script alter index rebuild online parallel oracle rebuild all indexes oracle index rebuild online vs offline oracle rebuild partitioned index index rebuild oracle best practice index rebuild script in oracle 11g
Views: 812 Oracle PL/SQL World
B*Tree Index Types (Indexes in Oracle-2)
 
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This video will cover different types of B-tree indexes: Descending index,Reverse key index,Key Compressed Index B-tree cluster index,Index Organized Table(IOT):
Views: 15284 Anindya Das
Oracle Tutorial || Oracle|Adv Sql | Partitioned Table Part - 2 by basha
 
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DURGASOFT is INDIA's No.1 Software Training Center offers online training on various technologies like JAVA, .NET , ANDROID,HADOOP,TESTING TOOLS ,ADF,INFORMATICA,TABLEAU,IPHONE,OBIEE,ANJULAR JS, SAP... courses from Hyderabad & Bangalore -India with Real Time Experts. Mail us your requirements to [email protected] so that our Supporting Team will arrange Demo Sessions. Ph:Call +91-8885252627,+91-7207212428,+91-7207212427,+91-8096969696. http://durgasoft.com http://durgasoftonlinetraining.com https://www.facebook.com/durgasoftware http://durgajobs.com https://www.facebook.com/durgajobsinfo......
Indexing in Oracle :B-Tree,Bitmap Indexing
 
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This Video is the 1st tutorial in the video series Indexing in Oracle , The video series explains in detail, What are indexes?It's types, what index should be used in which scenario and other important thing in basic terminology. Note :You may want to watch the video with a higher playback speed(1.25 if it suits you more)
Views: 10475 Tech Coach
Clustered vs. Nonclustered Index Structures in SQL Server
 
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Clustered and nonclustered indexes share many of the same internal structures, but they're fundamentally different in nature. Watch Microsoft Certified IT Professional Jon Seigel explain the similarities and differences of clustered and nonclustered indexes, using a real-world example to show how these structures work to improve the performance of SQL queries. Blog post on primary key vs. the clustered index: http://voluntarydba.com/post/2012/10/02/The-Primary-Key-vs-The-Clustered-Index.aspx CREATE INDEX statement reference: http://technet.microsoft.com/en-us/library/ms188783.aspx ALTER INDEX statement reference: http://technet.microsoft.com/en-us/library/ms188388.aspx Index navigation internals by example: http://sqlblog.com/blogs/paul_white/archive/2011/08/09/sql-server-seeks-and-binary-search.aspx Sample index data is from the AdventureWorksLT2008R2 sample database: http://awlt2008dbscript.codeplex.com/releases/view/46169 Visit my channel for more database administration videos: https://www.youtube.com/voluntarydba Subscribe to get notified about my latest videos: https://www.youtube.com/voluntarydba?sub_confirmation=1 Read additional content on my blog: http://voluntarydba.com Follow on Twitter: https://twitter.com/voluntarydba Like on Facebook: https://facebook.com/voluntarydba
Views: 275699 Voluntary DBA
Partitioning Enhancements in oracle 12c
 
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Oracle has made 4 significant enhancements in 12c. 1.Mixing Interval and Reference partitioning 2.DDL operations on multiple partitions 3.Global Index maintenance 4.Cascade Operations from parent to child, Truncate and drop This video explains the enhancements in detail with practical examples
Views: 1138 Tech Coach
Index Organized Tables
 
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Bases de Datos 2 Index Organized Tables Michelle Cersosimo Fernando Mata
Views: 782 Mich Cersosimo
B*Tree Index Fundamentals(Indexes in Oracle-1)
 
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Part -1 : Introduction to Indexes, B*Tree Indexes, Index scan methods. Part -2 : B*Tree Index Types(different types of B*Tree indexes) Part -3: Using B*Tree Indexes(When use B*Tree indexes, factors related to B*Tree Access) Part -4 : Index Organized Table Part -5 : Bitmap Indexes Part -6: Partitioned Indexes Part- 7: Other type of Indexes based on characteristics & use. Part -8: Managing Indexes
Views: 48697 Anindya Das
Reference partitioning in Oracle 11g
 
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The video explains Reference partitioning and its advantages in Oracle with real project example. It builds on the limitations of reference partitioning in oracle 11g (Interval partitioning) and scenarios where you should implement reference partitioning
Views: 1288 Tech Coach
Oracle Tutorial || Oracle|Adv Sql | Partitioned Table Part - 4 by basha
 
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DURGASOFT is INDIA's No.1 Software Training Center offers online training on various technologies like JAVA, .NET , ANDROID,HADOOP,TESTING TOOLS ,ADF,INFORMATICA,TABLEAU,IPHONE,OBIEE,ANJULAR JS, SAP... courses from Hyderabad & Bangalore -India with Real Time Experts. Mail us your requirements to [email protected] so that our Supporting Team will arrange Demo Sessions. Ph:Call +91-8885252627,+91-7207212428,+91-7207212427,+91-8096969696. http://durgasoft.com http://durgasoftonlinetraining.com https://www.facebook.com/durgasoftware http://durgajobs.com https://www.facebook.com/durgajobsinfo......
Composite Partitioning in Oracle
 
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This video is the 6th Video in the series partitioning in oracle. It explains the different composite partitioning approaches and in what scenario they should be used with real project use case explanations.
Views: 1984 Tech Coach
Oracle Tutorial || Oracle|Adv Sql | Partitioned Table Part - 5 by basha
 
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DURGASOFT is INDIA's No.1 Software Training Center offers online training on various technologies like JAVA, .NET , ANDROID,HADOOP,TESTING TOOLS ,ADF,INFORMATICA,TABLEAU,IPHONE,OBIEE,ANJULAR JS, SAP... courses from Hyderabad & Bangalore -India with Real Time Experts. Mail us your requirements to [email protected] so that our Supporting Team will arrange Demo Sessions. Ph:Call +91-8885252627,+91-7207212428,+91-7207212427,+91-8096969696. http://durgasoft.com http://durgasoftonlinetraining.com https://www.facebook.com/durgasoftware http://durgajobs.com https://www.facebook.com/durgajobsinfo......
BITMAP  and  BITMAP JOIN INDEX IN ORACLE explained
 
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The video explains BITMAP and BITMAP JOIN INDEX IN ORACLE and when you should create them on a column. BITMAP INDEXES should be dealt with carefully as they can lead to serious performance issues if the table is updated by multiple processes in parallel. Indexing Basics :https://www.youtube.com/watch?v=0X9bbtwTnuE&t=1095s Star and snowflake Schema :https://www.youtube.com/watch?v=Qq4yhhAk9fc&t=17s
Views: 2532 Tech Coach
Oracle || Indexes Part-1 by dinesh
 
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DURGASOFT is INDIA's No.1 Software Training Center offers online training on various technologies like JAVA, .NET , ANDROID,HADOOP,TESTING TOOLS ,ADF,INFORMATICA,TABLEAU,IPHONE,OBIEE,ANJULAR JS, SAP... courses from Hyderabad & Bangalore -India with Real Time Experts. Mail us your requirements to [email protected] so that our Supporting Team will arrange Demo Sessions. Ph:Call +91-8885252627,+91-7207212428,+91-7207212427,+91-8096969696. http://durgasoft.com http://durgasoftonlinetraining.com https://www.facebook.com/durgasoftware http://durgajobs.com https://www.facebook.com/durgajobsinfo......
List Partitioning in Oracle
 
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Understanding and creating list partition
Views: 51 Koenig Solutions
Index Organized Tables
 
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Creadores: Michelle Cersosimo Fernando Mata Universidad de Costa Rica - Bases de Datos 2 2014
Views: 386 Mich Cersosimo
Global Index rebuild scenario in Oracle Database 11g
 
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Why and How we need to rebuild global Index in Oracle 11g
Views: 2830 Athar Fahad
List partitioning in Oracle : Part 3
 
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This video explains list partitioning in detail with 2 real project examples. I recommend watching these 2 videos on partitioning prior to watching the current one. 1. https://www.youtube.com/watch?v=m3q4lrE671Y&t=25s 2. https://www.youtube.com/watch?v=OQ8LXbxLI5g&t=1312s
Views: 3941 Tech Coach
Oracle Tutorial || Oracle|Adv Sql | Partitioned Table Part - 6 by basha
 
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DURGASOFT is INDIA's No.1 Software Training Center offers online training on various technologies like JAVA, .NET , ANDROID,HADOOP,TESTING TOOLS ,ADF,INFORMATICA,TABLEAU,IPHONE,OBIEE,ANJULAR JS, SAP... courses from Hyderabad & Bangalore -India with Real Time Experts. Mail us your requirements to [email protected] so that our Supporting Team will arrange Demo Sessions. Ph:Call +91-8885252627,+91-7207212428,+91-7207212427,+91-8096969696. http://durgasoft.com http://durgasoftonlinetraining.com https://www.facebook.com/durgasoftware http://durgajobs.com https://www.facebook.com/durgajobsinfo......
Reorganizing Tables in Oracle
 
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The clip explains why reorganizing of tables may or may not be required and how to do it. Text version is here: https://uhesse.com/2010/08/23/reorganizing-tables-in-oracle-is-it-worth-the-effort/
What is the RANGE-HASH SUBPARTITIONS in Oracle ?
 
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Hi guys in my today scenario I'm going to explain with you What is the RANGE-HASH SUB-PARTITIONS in Oracle,Oracle database #RANGE-HASHSUBPARTITIONS Unbeatable,Unbreakable Platform..
Views: 1384 Oracle World
part 9 - list partition
 
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list partition, data warehousing, alter table
part 15 move partition
 
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move partition, alter table, data warehousing
03 How to configure List partition in Oracle
 
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Use list partitioning when you require explicit control over how rows map to partitions. You can specify a list of discrete values for the partitioning column in the description for each partition. This is different from range partitioning, where a range of values is associated with a partition, and from hash partitioning, where the user has no control of the row to partition mapping. List partitioning allows unordered and unrelated sets of data to be grouped and organized together very naturally The following example creates a table with list partitioning create table customers (custcode number(5), Name varchar2(20), Addr varchar2(10,2), City varchar2(20), Bal number(10,2)) Partition by list (city), Partition north_India values (‘DELHI’,’CHANDIGARH’), Partition east_India values (‘KOLKOTA’,’PATNA’), Partition south_India values (‘HYDERABAD’,’BANGALORE’,’CHENNAI’), Partition west India values (‘BOMBAY’,’GOA’); If a row is inserted in the above table then oracle maps the value of city column and whichever partition list matches the city column the row is stored in that partition.
Views: 671 OnLinE ReSoUrCe
Tables and Tables Clusters in Oracle
 
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https://dbagenesis.com/p/oracle-11g-advanced-dba DBA Genesis provides all you need to build and manage effective Oracle technology learning. We designed DBA Genesis as a simple to use yet powerful online Oracle learning system for students. Each of our courses is taught by an expert instructor, and every course is available on demand. Video talks about "what are table clusters inside Oracle database". One of video lessons from our Advanced DBA video course. Have a happy learning!
Views: 3728 DBA Genesis
Oracle Performance Tuning - Function Based Indexes
 
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A overview of the function based index and a common mistake which is made by most of us.
Views: 480 Saurabh Kumar
Oracle - Global is Local
 
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Views: 50 IFBTA
Oracle Performance Tips - Indexes
 
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Learn about index and types of indexes.
Views: 1993 Saurabh Kumar
Oracle || Indexes Part-3 by dinesh
 
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DURGASOFT is INDIA's No.1 Software Training Center offers online training on various technologies like JAVA, .NET , ANDROID,HADOOP,TESTING TOOLS ,ADF,INFORMATICA,TABLEAU,IPHONE,OBIEE,ANJULAR JS, SAP... courses from Hyderabad & Bangalore -India with Real Time Experts. Mail us your requirements to [email protected] so that our Supporting Team will arrange Demo Sessions. Ph:Call +91-8885252627,+91-7207212428,+91-7207212427,+91-8096969696. http://durgasoft.com http://durgasoftonlinetraining.com https://www.facebook.com/durgasoftware http://durgajobs.com https://www.facebook.com/durgajobsinfo......
How to create Virtual Columns in Oracle Database
 
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How to create Virtual Columns in Oracle Database 12c When queried, virtual columns appear to be normal table columns, but their values are derived rather than being stored on disc. The syntax for defining a virtual column is listed below. column_name [datatype] [GENERATED ALWAYS] AS (expression) [VIRTUAL] If the datatype is omitted, it is determined based on the result of the expression. The GENERATED ALWAYS and VIRTUAL keywords are provided for clarity only. The script below creates and populates an employees table with two levels of commission. It includes two virtual columns to display the commission-based salary. The first uses the most abbreviated syntax while the second uses the most verbose form. CREATE TABLE employees ( id NUMBER, first_name VARCHAR2(10), last_name VARCHAR2(10), salary NUMBER(9,2), comm1 NUMBER(3), comm2 NUMBER(3), salary1 AS (ROUND(salary*(1+comm1/100),2)), salary2 NUMBER GENERATED ALWAYS AS (ROUND(salary*(1+comm2/100),2)) VIRTUAL, CONSTRAINT employees_pk PRIMARY KEY (id) ); INSERT INTO employees (id, first_name, last_name, salary, comm1, comm2) VALUES (1, 'JOHN', 'DOE', 100, 5, 10); INSERT INTO employees (id, first_name, last_name, salary, comm1, comm2) VALUES (2, 'JAYNE', 'DOE', 200, 10, 20); COMMIT; Querying the table shows the inserted data plus the derived commission-based salaries. SELECT * FROM employees; ID FIRST_NAME LAST_NAME SALARY COMM1 COMM2 SALARY1 SALARY2 ---------- ---------- ---------- ---------- ---------- ---------- ---------- ---------- 1 JOHN DOE 100 5 10 105 110 2 JAYNE DOE 200 10 20 220 240 2 rows selected. SQL The expression used to generate the virtual column is listed in the DATA_DEFAULT column of the [DBA|ALL|USER]_TAB_COLUMNS views. COLUMN data_default FORMAT A50 SELECT column_name, data_default FROM user_tab_columns WHERE table_name = 'EMPLOYEES'; COLUMN_NAME DATA_DEFAULT ------------------------------ -------------------------------------------------- ID FIRST_NAME LAST_NAME SALARY COMM1 COMM2 SALARY1 ROUND("SALARY"*(1+"COMM1"/100),2) SALARY2 ROUND("SALARY"*(1+"COMM2"/100),2) 8 rows selected. SQL Notes and restrictions on virtual columns include: 1)Indexes defined against virtual columns are equivalent to function-based indexes. 2)Virtual columns can be referenced in the WHERE clause of updates and deletes, but they cannot be manipulated by DML. 3)Tables containing virtual columns can still be eligible for result caching. 4)Functions in expressions must be deterministic at the time of table creation, but can subsequently be recompiled and made non-deterministic without invalidating the virtual column. In such cases the following steps must be taken after the function is recompiled: a)Constraint on the virtual column must be disabled and re-enabled. b)Indexes on the virtual column must be rebuilt. c)Materialized views that access the virtual column must be fully refreshed. d)The result cache must be flushed if cached queries have accessed the virtual column. e)Table statistics must be regathered. 5)Virtual columns are not supported for index-organized, external, object, cluster, or temporary tables. 6)The expression used in the virtual column definition has the following restrictions: a.It cannot refer to another virtual column by name. b.It can only refer to columns defined in the same table. c.If it refers to a deterministic user-defined function, it cannot be used as a partitioning key column. e.The output of the expression must be a scalar value. It cannot return an Oracle supplied datatype, a user-defined type, or LOB or LONG RAW.
Views: 425 OracleDBA
Table Compression Enhancement in Oracle Database 11g R2
 
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Table Compression: Overview Oracle Database supports three methods of table compression: 1.Basic table compression 2.OLTP table compression Oracle Corporation recommends to compress all data to reduce storage costs. The Oracle database can use table compression to eliminate duplicate values in a data block. For tables with highly redundant data, compression saves disk space and reduces memory use in the database buffer cache. Table compression is transparent to database applications. The table_compression clause is valid only for heap-organized tables. The COMPRESS keyword enables table compression. The NOCOMPRESS keyword disables table compression. NOCOMPRESS is the default. With basic compression, the Oracle database compresses data at the time of performing bulk load using operations such as direct loads or CREATE TABLE AS SELECT. With COMPRESS FOR OLTP, the Oracle database compresses data during all DML operations on the table.
Views: 2273 Saurabh Joshi
Index Rebuild vs. Reorganize
 
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Some of my thoughts about performing either, or any at all. In some cases, I won't use indexes.
Views: 3928 SQLInSix Minutes
Heap tables
 
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Views: 1245 Nikolay Savvinov

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