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Oracle Indexes - Beginner
 
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Oracle Indexes - Beginner
Views: 64552 Chris Ostrowski
Why Isn't My Query Using an Index?
 
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“Why isn’t my query using an index?” is a common question people have when tuning SQL. This session explores the factors that influence the optimizer’s decision to answer this question. It does so by comparing fetching rows from a database table to finding all the red M&Ms a packet, and contrasts using an index range scan and a full table scan. It also introduces the concepts of blocks and the clustering factor. The session offers a discussion of how these affect the optimizer's calculations, and includes a demo of how these concepts work in practice using real SQL queries. This session is intended for developers who want to learn the basics of how the optimizer chooses between an index range or full table scan. Speaker: Chris Saxon
Views: 268 Oracle Developers
What Impact Do Indexes Have on Inserts?: Finding All the Red Sweets Part 0
 
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Creating indexes can improve query performance. Oracle must maintain the indexes however. This increases the work it must do whenever you modify data in indexed columns. In this video Chris looks at this overhead using a real world analogy - recording the color of all the candies stored in party bags! ============================ The Magic of SQL with Chris Saxon Copyright © 2015 Oracle and/or its affiliates. Oracle is a registered trademark of Oracle and/or its affiliates. All rights reserved. Other names may be registered trademarks of their respective owners. Oracle disclaims any warranties or representations as to the accuracy or completeness of this recording, demonstration, and/or written materials (the “Materials”). The Materials are provided “as is” without any warranty of any kind, either express or implied, including without limitation warranties or merchantability, fitness for a particular purpose, and non-infringement.
Views: 2598 The Magic of SQL
Oracle Database Indexes: Myths, Tips and Tricks
 
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In this tutorial, OCM John Watson will - via demonstrations - debunk these myths: Myth #1: Oracle Database does not index NULL Myth #2: A search that includes wildcards can't use an index if the wildcard precedes the string. Myth #3: Oracle will not use a function-based index unless the FBI is coded in the predicate. Myth #4: Indexes always help. The more indexes the better. See http://skillbuilders.com/free-oracle-tutorials for gigabytes of free Oracle video tutorials.
Views: 16121 SkillBuilders
Missing Index Hints in SQL Server Management Studio by Amit Bansal
 
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In this video, you will learn why you should not blindly follow the SSMS Missing Index Hints. Video resources including presentation, demo files, code snippets and more learning material is available on http://www.dataplatformgeeks.com/ (Join for free and access all the resources) Connect With The Speaker (Amit Bansal) -Follow on Twitter: https://twitter.com/A_Bansal -Follow on FaceBook at http://www.facebook.com/amit.r.bansal -Follow on LinkedIN: http://www.linkedin.com/in/amitbansal2010 -Facebook Page: https://www.facebook.com/AmitRSBansal/ Connect with SQLMaestros: http://sqlmaestros.com/ -http://www.twitter.com/SQLMaestros -https://www.facebook.com/SQLMaestros -Email us: [email protected] Have technical questions? Join the largest SQL group on FB www.facebook.com/groups/theSQLGeeks Our LinkedIn group https://www.linkedin.com/groups/6753546 DataPlatformGeeks (DPG) Community Join the fastest growing community of data & analytics professionals Why Join DPG? http://www.dataplatformgeeks.com/ -Attend all events hosted by DPG, including SQLMaestros Special Events -Get access to free videos, labs, magazines and host of learning resources -Download all events & conference material -Learn new skills. Sharpen existing skills -Be part of Asia’s Largest Data/Analytics Community -Opportunity to be a regional mentor & speaker at our events -Immense technical & professional development Do you know about Data Platform Summit? http://www.DPS10.com
Views: 847 SQLMaestros
Oracle: Tune Your SQL Without Hints or Indexes! - Long Introduction
 
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"But I can’t change the queries that run in my database,” you say. Not a problem! This webinar we explore the underutilized art of rewriting a SQL query in order to make it run faster. I'll show you how to make your SQL query performance skyrocket simply by changing the SQL text. But even if you truly can't change the SQL, I'll also demonstrate how you can hurdle this issue too. This webinar will be presented by our most active OraPub SLACK member, Kaley Crum! To watch the full webinar go to www.oraoub.com/webinars
Views: 36 OraPub, Inc.
SQL 12c  Tutorial 19 : SQL  IDENTITY Column for generating Sequence Values by default
 
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SQL 12c Tutorial 19 : SQL IDENTITY Column for generating Sequence Values by default SQL 12c Tutorial for beginners Oracle SQL 12c Tutorial for beginners SQL 12c New Features Identity columns
Views: 660 TechLake
Oracle SQL Performance Tuning for Developers: Understand Explain Plans
 
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Understanding Explain Plans is an excerpt from Oracle SQL Performance Tuning for Developers: http://www.informit.com/store/oracle-sql-performance-tuning-for-developers-livelessons-9780134117027 6+ Hours of Video Instruction The focus of Oracle SQL Performance Tuning for Developers LiveLessons is to illustrate coding techniques that ensure a consistent response time between instances and releases of the Oracle database. This course works closely with performance tuning of actual SQL statements. Description In this video training, Dan Hotka starts out with a complete overview of the Oracle architecture so students can get an understanding how their SQL and applications can take advantage of the computing environment. This course then goes in-depth on understanding and controlling the Explain Plan, which is how and in what order Oracle retrieves data. The discussion includes considerable detail, with SQL examples, on how the optimizers--both rule-based and cost-based, but mostly cost-based--make their decisions. Students will work with a variety of SQL statements, reviewing Explain Plans and making changes to make these SQL statements perform better. Lectures include index design, using hints and coding style to control the Explain Plans, and how to use useful tools such as index monitoring, SQL Trace, and the PL/SQL profiler. This LiveLessons course takes a close look at indexes: how Oracle selects them, why they are sometimes not used, and how to tell if indexes are being used. This course includes Oracle10g, Oracle11g, and Oracle12c SQL tuning topics. Skill Level Intermediate Learn How To Read and understand Explain Plan content Review an Explain Plan and tell quickly if this is a good plan Understand a good index column candidate from a not-so-good candidate Quickly tell the likelihood if your SQL will use an existing index Use coding and a variety of Hints (directives) that can produce better performing SQL Execute and interpret SQL trace output Who Should Take This Course Oracle programmers Oracle database administrators who need additional training on SQL tuning Course Requirements Working knowledge of the SQL query language http://www.informit.com/store/oracle-sql-performance-tuning-for-developers-livelessons-9780134117027
Views: 3239 LiveLessons
oracle interview question oracle index function based index
 
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Title: Oracle Interview Question - oracle index related questions - Function based index in oracle Description: Oracle Interview Question - oracle index related questions 1. What is Index? How to create index? 2. What are the types of index? 3. How to find the list of indexes for a given table? 4. Explain B-tree index 5. Explain Bitmap index 6. Explain "Function based" index 7. Explain "Reverse Key" index 8. When to choose what type of index? 9. How to know index is being used? 10. How to monitor index usage? 11. What are the advantages/drawbacks of indexes?
Views: 72 Siva Academy
Tune Your Oracle SQL Without Hints or Indexes! - Preview Introduction
 
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“But I can’t change the queries that run in my database,” you say. Not a problem! This webinar we explore the underutilized art of rewriting a SQL query in order to make it run faster. I'll show you how to make your SQL query performance skyrocket simply by changing the SQL text. But even if you truly can't change the SQL, I'll also demonstrate how you can hurdle this issue too. This webinar will be presented by our most active OraPub SLACK member, Kaley Crum! Go Kaley!! This webinar will be on Wed Sept 12th 2018 at 7am PT. For details on how you can see the full webinar or webinar recording post date, go to www.orapub.com
Views: 30 OraPub, Inc.
Why Won't Oracle Use My Index - 12c Attribute Clustering - Lesson 1
 
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Sometimes a poor clustering factor is the cause when Oracle Database cost based optimizer does not choose to use an index. With Oracle 12c (12.1.0.2 EE) offers a new feature that can really help - "Atrribute Clustering". This is implemented with a new keyword on CREATE TABLE - "CLUSTERING BY LINEAR ORDER". In this Free Tutorial from SkillBuilders and Oracle Certified Master DBA John Watson, you'll get a brief refresher on clustering factor and a demonstration of CREATE TABLE - "CLUSTERING BY LINEAR ORDER" - so the CBO will use your index! In this first lesson, John will provide a brief review of clustering factor. See all 6 lessons - FREE - at http://www.skillbuilders.com/12c-attribute-clustering
Views: 358 SkillBuilders
Advanced Indexing for Beginners
 
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Advanced Indexing for Beginners Description: Indexing doesn't have to be hard, but you need to have the right level of understanding to get the most out of it. Knowing what's going on with different types of indexes, and how your index choices affect various components of the SQL engine can cause you to look at indexing in a new way. This demo-heavy session will take you on a journey from the basics of indexing through to advanced concepts that become simple when viewed correctly, using practical examples to explain the theory. Rob Farley is not your average speaker. Sure, he's an MCM, MCT, and MVP (since 2006). Sure, he runs a Gold Partner consultancy (LobsterPot Solutions) with two other Data Platform MVPs on the team. Sure he's written books and heads up the Adelaide SQL Server User Group. Sure, he's spent time on the PASS board and on the Australian Computer Society executive. But when Rob gives presentations he does so without slides - just demos - and challenges how you think about data. You can read some of Rob's work at blogs.lobsterpot.com.au, or at sqlperformance.com, or catch him on Twitter at @rob_farley.
Views: 632 DBAFundamentals
Efficient Function Calls From SQL (Part 6) : Function-Based Indexes
 
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The sixth part of a mini-series of videos showing how you can improve the performance of function calls from SQL. In this episode, we look at using function-based indexes to improve the performance of queries that use function calls in the WHERE clause. For more information see: https://oracle-base.com/articles/8i/function-based-indexes https://oracle-base.com/articles/misc/efficient-function-calls-from-sql#functions-in-the-where-clause Website: https://oracle-base.com Blog: https://oracle-base.com/blog Twitter: https://twitter.com/oraclebase Cameo by Ronald Bradford : Blog: http://ronaldbradford.com/blog/ Twitter: https://twitter.com/RonaldBradford Cameo appearances are for fun, not an endorsement of the content of this video.
Views: 1406 ORACLE-BASE.com
Efficient Function Calls From SQL (Part 2) : The DETERMINISTIC Hint
 
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The second part of a mini-series of videos showing how you can improve the performance of function calls from SQL. In this episode, we take a look at the DETERMINISTIC hint. For more information see: https://oracle-base.com/articles/misc/efficient-function-calls-from-sql#deterministic-hint Website: https://oracle-base.com Blog: https://oracle-base.com/blog Twitter: https://twitter.com/oraclebase Cameo by Dana Singleterry : Blog: https://blogs.oracle.com/dana/ Twitter: https://twitter.com/dsingleterry Cameo appearances are for fun, not an endorsement of the content of this video.
Views: 2247 ORACLE-BASE.com
Efficient Function Calls From SQL (Part 5) : Pipelined Table Functions
 
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The fifth part of a mini-series of videos showing how you can improve the performance of function calls from SQL. In this episode, we compare the performance of conventions table functions with pipelined table functions. For more information see: https://oracle-base.com/articles/misc/pipelined-table-functions https://oracle-base.com/articles/misc/efficient-function-calls-from-sql Website: https://oracle-base.com Blog: https://oracle-base.com/blog Twitter: https://twitter.com/oraclebase Cameo by Mike Dietrich : Blog: https://blogs.oracle.com/UPGRADE Twitter: https://twitter.com/MikeDietrichDE Cameo appearances are for fun, not an endorsement of the content of this video.
Views: 11237 ORACLE-BASE.com
Oracle Cost Based Optimizer Basics
 
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When it comes to writing efficient queries there are a few key concepts that need to be understood. One of them is the Oracle Cost-Based Optimizer (CBO). Although it's called a cost-based optimizer it's actually not the cost we need to focus on primarily to understand why the optimizer makes certain decisions. In this webinar, you will learn the basics of the CBO, see why it is crucial that the optimizer's picture of the data fits reality, why cardinality and selectivity estimates matter so muc
Views: 58254 Redgate Videos
SQL: Explain Plan for knowing the Query performance
 
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In this tutorial, you'll learn how to compare queries to know the better performance query..
Views: 94385 radhikaravikumar
Oracle SQL Performance Tuning for Developers: Introduction
 
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This video is an introduction to Oracle SQL Performance Tuning for Developers: http://www.informit.com/store/oracle-sql-performance-tuning-for-developers-livelessons-9780134117027 6+ Hours of Video Instruction The focus of Oracle SQL Performance Tuning for Developers LiveLessons is to illustrate coding techniques that ensure a consistent response time between instances and releases of the Oracle database. This course works closely with performance tuning of actual SQL statements. Description In this video training, Dan Hotka starts out with a complete overview of the Oracle architecture so students can get an understanding how their SQL and applications can take advantage of the computing environment. This course then goes in-depth on understanding and controlling the Explain Plan, which is how and in what order Oracle retrieves data. The discussion includes considerable detail, with SQL examples, on how the optimizers--both rule-based and cost-based, but mostly cost-based--make their decisions. Students will work with a variety of SQL statements, reviewing Explain Plans and making changes to make these SQL statements perform better. Lectures include index design, using hints and coding style to control the Explain Plans, and how to use useful tools such as index monitoring, SQL Trace, and the PL/SQL profiler. This LiveLessons course takes a close look at indexes: how Oracle selects them, why they are sometimes not used, and how to tell if indexes are being used. This course includes Oracle10g, Oracle11g, and Oracle12c SQL tuning topics. Skill Level Intermediate Learn How To Read and understand Explain Plan content Review an Explain Plan and tell quickly if this is a good plan Understand a good index column candidate from a not-so-good candidate Quickly tell the likelihood if your SQL will use an existing index Use coding and a variety of Hints (directives) that can produce better performing SQL Execute and interpret SQL trace output Who Should Take This Course Oracle programmers Oracle database administrators who need additional training on SQL tuning Course Requirements Working knowledge of the SQL query language http://www.informit.com/store/oracle-sql-performance-tuning-for-developers-livelessons-9780134117027
Views: 3075 LiveLessons
What is REVERSE INDEX? What does REVERSE INDEX mean? REVERSE INDEX meaning & explanation
 
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What is REVERSE INDEX? What does REVERSE INDEX mean? REVERSE INDEX meaning - REVERSE INDEX definition - REVERSE INDEX explanation. Source: Wikipedia.org article, adapted under https://creativecommons.org/licenses/by-sa/3.0/ license. SUBSCRIBE to our Google Earth flights channel - https://www.youtube.com/channel/UC6UuCPh7GrXznZi0Hz2YQnQ Database management systems provide multiple types of indexes to improve performance and data integrity across diverse applications. Index types include b-trees, bitmaps, and r-trees. In database management systems, a reverse key index strategy reverses the key value before entering it in the index. E.g., the value 24538 becomes 83542 in the index. Reversing the key value is particularly useful for indexing data such as sequence numbers, where each new key value is greater than the prior value, i.e., values monotonically increase. Reverse key indexes have become particularly important in high volume transaction processing systems because they reduce contention for index blocks. Reversed key indexes use b-tree structures, but preprocess key values before inserting them. Simplifying, b-trees place similar values on a single index block, e.g., storing 24538 on the same block as 24539. This makes them efficient both for looking up a specific value and for finding values within a range. However if the application inserts values in sequence, each insert must have access to the newest block in the index in order to add the new value. If many users attempt to insert at the same time, they all must write to that block and have to get in line, slowing down the application. This is particularly a problem in clustered databases, which may require the block to be copied from one computer's memory to another's to allow the next user to perform their insert. Reversing the key spreads similar new values across the entire index instead of concentrating them in any one leaf block. This means that 24538 appears on the same block as 14538 while 24539 goes to a different block, eliminating this cause of contention. (Since 14538 would have been created long before 24538, their inserts don't interfere with each other.) Reverse indexes are just as efficient as unreversed indexes for finding specific values, although they aren't helpful for range queries. Range queries are uncommon for artificial values such as sequence numbers. When searching the index, the query processor simply reverses the search target before looking it up. Typically, applications delete data that is older on average before deleting newer data. Thus, data with lower sequence numbers generally go before those with higher values. As time passes, in standard b-trees, index blocks for lower values end up containing few values, with a commensurate increase in unused space, referred to as "rot". Rot not only wastes space, but slows query speeds, because a smaller fraction of a rotten index's blocks fit in memory at any one time. In a b-tree, if 14538 gets deleted, its index space remains empty. In a reverse index, if 14538 goes before 24538 arrives, 24538 can reuse 14538's space.
Views: 713 The Audiopedia
SQL Hints, Tips, Tricks, and Tuning
 
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What is the difference between inner, outer, cross and natural join? What is a correlated subselect? What is the advantage and what the disadvantage of an index. Is NOT and OR evil? When do I need normalisation and when denormalisation? All this questions and lots of other performance tips and tricks on SQL level will be given in the talk.
Views: 14651 Andrea Ross
How can I speed up a query if an index cannot help?
 
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blog: connor-mcdonald.com Highlights from the April DBA Office Hours session. Office Hours is 100% free Q&A sessions held every month by Oracle experts to help you succeed with the Oracle suite of technologies. Music: Smells Like Summer - Del (Vlog Music No Copyrighted) Video Link: https://youtu.be/IrkMsqcOjGU
Views: 1026 Connor McDonald
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: 282046 Voluntary DBA
【VDEDU】Unusable indexes use
 
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Unusable indexes in Oracle, DML statements are not use the index to its maintenance, at the same time the optimizer will not use the index. Unusable indexes no segment exists. Unavailable index index becomes available methods are: 1. Place the index can not be truncate operation corresponding table; 2.rebuild index; In addition, the query optimizer can use conversion method expand table so that the SQL statement has encountered unusable index partition table to generate better execution plans.
Views: 62 崔旭
PL/SQL tutorial 57: PL/SQL Collection Associative Array in Oracle Database
 
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Manish Sharma from RebellionRider presents you the latest PL/SQL tutorial on Collection ASSOCIATIVE ARRAY. In this video, you will learn – - What are Associative Arrays? - How to create Associative Arrays? - How to Insert & Update the data of Associative Array and - How to retrieve the data from an Associative array using two different ways? So if you are wondering whether associative array is a persistent form of collection or not; Is it bounded or unbounded in nature; why should we use this specific collection over others such as VARRAY or Nested Table; What are the differences or similarities between associative array and other collections? Then go ahead and watch the video to find out the answers to all these questions. Hope you will enjoy watching. Do make sure to Like and Share this post/video because that will help others in learning as well as help me and my channel in reaching out. This way we can educate more and more people for FREE. Most importantly SUBSCRIBE to the channel as many such interesting tutorials are coming your way. Thanks. ------------------------------------------------------------------------ ►►►LINKS◄◄◄ Blog: http://bit.ly/associative-array Previous Tutorial ►While Loop: https://youtu.be/IIlc4Sr7kFE ------------------------------------------------------------------------- ►Make sure you SUBSCRIBE and be the 1st one to see my videos! ------------------------------------------------------------------------- ►►►Find me on Social Media◄◄◄ Follow What I am up to as it happens on https://twitter.com/rebellionrider http://instagram.com/rebellionrider https://plus.google.com/+Rebellionrider http://in.linkedin.com/in/mannbhardwaj/ ___Facebook Official Page of Manish Sharma___ https://www.facebook.com/TheRebellionRider/ ___Facebook Official Page of RebellionRider.com___ https://www.facebook.com/RebellionRider.official/ You can also Email me at for E-mail address please check the About section Please please LIKE and SHARE my videos it makes me happy. Thanks for liking, commenting, sharing and watching more of our videos This is Manish from RebellionRider.com ♥ I LOVE ALL MY VIEWERS AND SUBSCRIBERS
Views: 11694 Manish Sharma
Using DBMS_XPLAN.DISPLAY_CURSOR to examine execution plans
 
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In this video I describe how you can use Oracle's DBMS_XPLAN.DISPLAY_CURSOR to examine the execution plan for a SQL statement that has recently been executed and determine if that plan is optimal or not and where you might be able to optimize it.
Views: 7463 Maria Colgan
Making Smart Scan for Exadata Work (Demonstration)
 
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Making Smart Scan Work - Demo I'll go through a simple example of the kind of thing we need to think about when trying to achieve Smart Scan. Let me just enable tracing, run a simple query, select and * from *. Now, there's my query. The result set comes back, and how is it executed? An index full scan with the PK* index. The optimizer is intelligent enough to know that my query can be satisfied purely by reading the index and therefore it didn't have to go to the table at all. It looks very good. Well, it wasn't. Index full scans are an operation that cannot be offloaded. So, to execute that statement, every block of that index was delivered into the buffer cache of my own database instance, and the compute node then has to do the work of extracting those values. What can we do about it? One solution would be to hint the code. I select and demand an index fast full scan, and now we see the magic word "storage." An index fast full scan is offloadable, because an index fast full scan can do direct reads. An alternative approach? Well, you might not want to hint many, many thousands of lines of code. An alternative approach would be to do it through DDL. For example, take that index, make it invisible. Now run my statements without any hint at all, table access storage full, and that was offloaded. Having made the index invisible, Oracle has no option but a full-table scan, and a full-table scan is offloadable. Now, this means I have three options of this very simple example. I can let the optimizer get on with what it wants to do, and then I use an index that I'm doing block serving into the buffer cache. I can hint the code, index fast full scan. That's probably the best option for performance, but it's also the most work. In this intervening case, I make the index invisible so that it will still be used of course for enforcing the primary key constraints, but it will not be visible to the optimizer and therefore influence the optimizer towards using plans that can be offloaded the Smart Scan. Making the choice between this and influencing the optimizer in the correct direction is an extremely difficult job, and it is not always easy to determine what is going to be the best solution.
Views: 3131 SkillBuilders
Setting up Full text index on database table
 
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In this video I will show you how to setup up full text index on database tables..
Views: 1822 Adlai King
Using the qb_name Hint in Oracle Database
 
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Oracle ACE Ric Van Dyke shares a tip on using the qb_name hint in Oracle Database, and on how naming query blocks can make debugging a lot easier.
Four Steps to Oracle SQL Tuning  - A Methodolgy
 
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Learn a predictable and repeatable methodology for tuning Oracle SQL statements. Just four steps that you should always follow when tuning an SQL statement. (Note this video does not contain examples of how to apply the four steps, just what the steps are.) Oracle Certified Master John Watson presents. John concludes with a brief overview of how SkillBuilders SQL tuning course provides the information you need to apply the four steps. Learn more about SkillBuilders SQL Tuning course http://skillbuilders.com/oracle-sql-tuning-training 1. What is Oracle doing? (explain plan, trace) 2. Why is Oracle doing it that way? (analyze the execution plan) 3. Is there a better way? Test! 4. If there's a better way, push the CBO towards the better way.
Views: 11878 SkillBuilders
Hints and Tips - SQL*Plus tricks
 
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It's been around forever... but that does not make it obsolete. Here's how you can get the most out of SQL*Plus ========================================­­============== Copyright © 2015 Oracle and/or its affiliates. Oracle is a registered trademark of Oracle and/or its affiliates. All rights reserved. Other names may be registered trademarks of their respective owners. Oracle disclaims any warranties or representations as to the accuracy or completeness of this recording, demonstration, and/or written materials (the “Materials”). The Materials are provided “as is” without any warranty of any kind, either express or implied, including without limitation warranties or merchantability, fitness for a particular purpose, and non-infringement.
Views: 3101 Connor McDonald
Two Dudes and a Database
 
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Two Aussie Oracle ACE Alumni catch up in Perth at the end of a half-day session on database features and data clustering. blog: https://connor-mcdonald.com twitter: https://twitter.com/connor_mc_d Richard's Blog: https://richardfoote.wordpress.com Richard's Indexing Webinar: https://richardfooteconsulting.com/indexing-webinar/ Trivadis Performance Days: https://www.trivadis.com/en/training/performance-days-2018-tvdpdays Gather Plan Statistics hint: https://docs.oracle.com/en/database/oracle/oracle-database/18/tgsql/optimizer-statistics-concepts.html DBMS_REDEFINTION docs: https://docs.oracle.com/en/database/oracle/oracle-database/18/arpls/DBMS_REDEFINITION.html Subscribe for new tech videos every week Music: https://soundcloud.com/joakimkarud Any endorsement of non-Oracle products and/or companies in this video should not be viewed as an official endorsement from Oracle Corporation.
Views: 365 Connor McDonald
Range Partitioning in Oracle
 
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In this video I have explained what is range partitioning along with it's 2 real project use cases. I have also explained interval Partitioning as an extension of Range partitioning If you have not watched my Initial Videos on partitioning I will recommended watching them before watching this video Apologies for the 10 second video glitch between 6 and 7 minutes :(
Views: 3642 Tech Coach
exchange Partition , Move partition in oracle
 
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exchange Partition , Move partition in oracle Possible operations with partitions SQL Tutorial SQL Tutorial for beginners PLSQL Tutorial PLSQL Tutorial for beginners PL/SQL Tutorial PL SQL Tutorial PL SQL Tutorial for beginners PL/SQL Tutorial for beginners Oracle SQL Tutorial Add Drop Rename Split Move ( Moving from Tablespace to tablespace) Exchange (Table to Table(non Partitioned table)) not partitioned only exchanging data (p)
Views: 1039 TechLake
Bitmap vs B Tree Indexes by Gavi Yatnalli @UrbanPro
 
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Gavi has 5 years of experience as plsql developer on various domains including but not restricted to Banking, Telecom and Healthcare. Strong and in-depth knowledge of Oracle database and PL/SQL and an excellent teaching approach. To know more about his classes visit https://www.urbanpro.com/pune/gavi-yatnalli/3073017
Views: 75 UrbanPro.com
Oracle Core,  Лекция 4
 
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Ссылка на файл с презентацией: https://docs.google.com/presentation/d/1hqsC6hEGybAbEEPko56razF7eLBJQEZ3L-ECWtp7rbM/edit?usp=sharing (презентация может быть с анимацией) Ссылка на краткий конспект лекции:https://docs.google.com/document/d/1UFayi0YIXxLrRuj4-JZj-jooyvpoa4rKLOryBloTtag/edit?usp=sharing 1. Create table: permanent tables, temporary tables (on commit delete/preserve rows) 2. Physical properties таблицы: tablespace, logging, pctfree, pctused, initrans 3. Pctfree и pctused 4. Initrans и maxtrans 5.Storage clause: initial, next, minextents, maxextents, pctincrease, freelists, freelist groups, optimal, buffer_pool (keep,recycle), flash_cache (keep, none), encrypt 6. Table properties: column_properties, cache, result_cache, enable_disable_clause, flashback_archive_clause 7. Alter table: column_clause, constraint_clause, alter_table_partitioning, move_table_clause, enable_disable_clause, rename to, shrink space 8. High water mark. Low high water mark 9. Create index: table index clause, index_expr, index_properties, unusable 10. Reverse indexes 11. Function based indexes 12. Alter index: сжатие (shrink space), параллелизм, физические атрибуты (pctfree, pctused, initrans), logging/nologging, rebuild, enable/disable, unusable, visible/invisible, rename to 13. Индекс по внешнему ключу 14. Причины неиспользования индексов 15. Оператор truncate 16. Неявный commit при выполнении ddl 17. Словари данных Oracle Database, БД Oracle, вебинар Oracle, презентация Oracle, урок Oracle, лекция Oracle, обучение Oracle
Oracle Exadata Smart Scan - Limitations and Best Practices
 
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Smart Scan is a wonderful capability, but you don't always get it. It's impossible for many execution plans, and this is a major restriction. If you think about what a Smart Scan actually does, it delivers individual columns, individual rows back to the instance. Now, a buffer cache can accept only blocks. Therefore, Smart Scan cannot possibly put those columns of rows into the buffer cache. It's simply not formatted appropriately. So, a Smart Scan has to return values directly into the session's PGA or, to put it another way, the only access method that can use Smart Scan is direct read. Well, what access methods can use direct read? There are only two, which are table full scan and index fast full scan. Any other access method, typically index range scan, table access by row ID, cannot use a Smart Scan. The second major issue, there are strict limitations of the type of objects that can be accessed through Smart Scan. It really is only heap tables. You can't use indexes. You can't use clusters. You can't use IOTs. Heap tables only. Perhaps hardest to track down and giving sometimes very erratic results is that Smart Scan can be interrupted by various conditions. You've met all the requirements for Smart Scan, directory and so on, got the right execution plan. The Smart Scan starts and then hits something that causes a problem. Issues that we know cause problems are, for instance, read consistency, also delayed block cleanout, change rows. Any of those issues and a few others mean that the storage tier will have to interrupt its Smart Scan, deliver complete blocks into that buffer cache, let your session then do what is necessary to the block, and only then can the Smart Scan proceed. Now, in order to maximize the use of Smart Scan, there may be quite a lot of work. Very often, you'll have to adjust your index structures. Making them invisible is a nice technique there. There are many, many, many parameters that can influence the likelihood of achieving a Smart Scan, and almost inevitably you're going to be rewriting a lot of hint SQL and putting hints in it to get the correct execution plans that can enable a Smart Scan to occur. This is all because of one fundamental problem; the optimizer is not in any way aware of the Exadata. The optimizer develops an execution plan in exactly the way it would without the Exadata storage. The use of Smart Scan, the awareness of Exadata comes at the next level down. The optimizer develops the plan through a normal pass and then passes it through to the SQL execution engine, and it's the SQL execution engine that determines, on a case-by-case basis, whether to use the Smart Scan. This means that you might develop a plan and execute the statement 50 times. Forty-nine times, you get a Smart Scan. The 50th time, for whatever reason, the SQL execution engine decides not to. This can result in somewhat erratic performance.
Views: 1637 SkillBuilders
Oracle LISTAGG Function
 
04:57
https://www.databasestar.com/oracle-listagg/ The Oracle LISTAGG function allows you to aggregate or combine string values from multiple rows into a single row. For example, it turns this data: FIRST_NAME Adam Brad Carrie Into this data: FIRST_NAME Adam, Brad, Carrie The same data is shown, but it’s in one row and not multiple. It’s a valuable string manipulation function, and once you know what it is and how it works, you’ll be able to use it in your queries as needed. So what does it look like? The function is: LISTAGG ( measure_expr [, delimiter]) WITHIN GROUP (order_by_clause) [OVER query_partition_clause] These parameters are: measure_expr: This is a column or expression that you want to concatenate the values of. In the example above, it was the first_name column. Mandatory. delimiter: This is the character between each of the measure_expr values. Optional, the default is a comma. order_by_clause: This is the order that the values from the measure_expr are listed. Mandatory. query_partition_clause: This allows you to use LISTAGG as an analytic function, allowing you to show LISTAGG in groups for different rows. One thing to be aware of is that the output of the Oracle LISTAGG function is limited to 4,000 bytes. If you get more than this, you’ll receive an error. The most common way around this that I’ve seen is to write a custom function and use a CLOB. Watch the video to find out more and see some examples. For more information about the Oracle LISTAGG function, including all of the SQL shown in this video and the examples, read the related article here: https://www.databasestar.com/oracle-listagg/
Views: 2371 Database Star
Sql server query plan cache
 
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Text version of the video http://csharp-video-tutorials.blogspot.com/2017/04/sql-server-query-plan-cache.html Slides http://csharp-video-tutorials.blogspot.com/2017/04/sql-server-query-plan-cache_12.html All SQL Server Text Articles http://csharp-video-tutorials.blogspot.com/p/free-sql-server-video-tutorials-for.html All SQL Server Slides http://csharp-video-tutorials.blogspot.com/p/sql-server.html All SQL Server Tutorial Videos https://www.youtube.com/playlist?list=PL08903FB7ACA1C2FB All Dot Net and SQL Server Tutorials in English https://www.youtube.com/user/kudvenkat/playlists?view=1&sort=dd All Dot Net and SQL Server Tutorials in Arabic https://www.youtube.com/c/KudvenkatArabic/playlists In this video we will discuss 1. What happens when a query is issued to SQL Server 2. How to check what is in SQL Server plan cache 3. Things to consider to promote query plan reusability What happens when a query is issued to SQL Server In SQl Server, every query requires a query plan before it is executed. When you run a query the first time, the query gets compiled and a query plan is generated. This query plan is then saved in sql server query plan cache. Next time when we run the same query, the cached query plan is reused. This means sql server does not have to create the plan again for that same query. So reusing a query plan can increase the performance. How long the query plan stays in the plan cache depends on how often the plan is reused besides other factors. The more often the plan is reused the longer it stays in the plan cache. How to check what is in SQL Server plan cache SELECT cp.usecounts, cp.cacheobjtype, cp.objtype, st.text, qp.query_plan FROM sys.dm_exec_cached_plans AS cp CROSS APPLY sys.dm_exec_sql_text(plan_handle) AS st CROSS APPLY sys.dm_exec_query_plan(plan_handle) AS qp ORDER BY cp.usecounts DESC As you can see we have sorted the result set by usecounts column in descending order, so we can see the most frequently reused query plans on the top. usecounts - Number of times the plan is reused objtype - Specifies the type of object text - Text of the SQL query query_plan - Query execution plan in XML format To remove all elements from the plan cache use the following command DBCC FREEPROCCACHE In older versions of SQL Server up to SQL Server 6.5 only stored procedure plans are cached. The query plans for Adhoc sql statements or dynamic sql statements are not cached, so they get compiled every time. With SQL Server 7, and later versions the query plans for Adhoc sql statements and dynamic sql statements are also cached. Things to consider to promote query plan reusability For example, when we execute the following query the first time. The query is compiled, a plan is created and put in the cache. Select * From Employees Where FirstName = 'Mark' When we execute the same query again, it looks up the plan cache, and if a plan is available, it reuses the existing plan instead of creating the plan again which can improve the performance of the query. However, one important thing to keep in mind is that, the cache lookup is by a hash value computed from the query text. If the query text changes even slightly, sql server will not be able to reuse the existing plan. For example, even if you include an extra space somewhere in the query or you change the case, the query text hash will not match, and sql server will not be able find the plan in cache and ends up compiling the query again and creating a new plan. Another example : If you want the same query to find an employee whose FirstName is Steve instead of Mark. You would issue the following query Select * From Employees Where FirstName = 'Steve' Even in this case, since the query text has changed the hash will not match, and sql server will not be able find the plan in cache and ends up compiling the query again and creating a new plan. This is why, it is very important to use parameterised queries for sql server to be able to reuse cached query plans. With parameterised queries, sql server will not treat parameter values as part of the query text. So when you change the parameters values, sql server can still reuse the cached query plan. The following query uses parameters. So even if you change parameter values, the same query plan is reused. Declare @FirstName nvarchar(50) Set @FirstName = 'Steve' Execute sp_executesql N'Select * from Employees where [email protected]', N'@FN nvarchar(50)', @FirstName One important thing to keep in mind is that, when you have dynamic sql in a stored procedure, the query plan for the stored procedure does not include the dynamic SQL. The block of dynamic SQL has a query plan of its own. Summary: Never ever concatenate user input values with strings to build dynamic sql statements. Always use parameterised queries which not only promotes cached query plans reuse but also prevent sql injection attacks.
Views: 22862 kudvenkat
SCPT 46:Oracle Storage Termininology:  High Water Mark and Free Lists
 
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Oracle DBA Tutorials For Full Course Experience Please Go To http://mentorsnet.org/course_preview?course_id=6 Full Course Experience Includes 1. Access to course videos and exercises 2. View & manage your progress/pace 3. In-class projects and code reviews 4. Personal guidance from your Mentors
Views: 17911 Oresoft LWC
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......
Ronald Vargas Quesada - Oracle Database Performance Tuning con SQL
 
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En esta presentación Ronald de Costa Rica nos muestra cómo mejorar la performance de la base de datos a partir de un correcta escritura de las sentencias SQL.
Views: 6215 OracleAmericaLatina
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: 439 OracleDBA
SQL: Spooling
 
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In this tutorial, you'll learn to spool the executed queries to a file
Views: 23250 radhikaravikumar
Oracle Database SQL Tuning with Constraints - Lesson 1 of 5
 
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Learn how to tune SQL - especially in Data Warehouse environments - with Constraints. Constraints provide critical information to the Cost Based Optimizer in the Oracle Database. Don't drop your constraints for query performance! In these 5 lessons, Oracle Certified Master DBA John Watson will demonstrate how constraints - unique, foreign key, not null - improve the execution plan and thus performance of SQL in an Oracle database. View all 5 lessons, free at http://www.skillbuilders.com/oracle-database-sql-tuning-with-constraints.
Views: 894 SkillBuilders
AskTOM TV - Direct path read
 
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A video to help you understand the "thought process" behind answering AskTom questions. In this episode, we look at direct path reads and how they interact with objects that may already have changed buffers in the buffer cache blog: https://connor-mcdonald.com
Views: 518 Connor McDonald
Oracle Data Redaction
 
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A brief overview of using Oracle Data Redaction in Oracle Database 12c. For more information see: https://oracle-base.com/articles/12c/data-redaction-12cr1 Website: https://oracle-base.com Blog: https://oracle-base.com/blog Twitter: https://twitter.com/oraclebase Cameo by Heli Helskyaho Blog: https://helifromfinland.wordpress.com/ Twitter: https://twitter.com/helifromfinland Cameo appearances are for fun, not an endorsement of the content of this video.
Views: 2622 ORACLE-BASE.com
ORACLE EXPLAIN PLAN FUNDAMENTALS
 
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This Tutorial will explain basics of Oracle 11g EXPLAIN Plan by using this ppt & some hands-on in Oracle 11g R2 Database.This tutorial will include below topics. Understanding EXPLAIN plan. Set up & Use EXPLAIN Plan. Explain PLAN_TABLE & related scripts & DBMS_XPLAN.DISPLAY. Generate & View EXPLAIN Plan. Read & Interpret basics of EXPLAIN Plan. EXPLAIN PLAN limitations.
Views: 159524 Anindya Das
Oracle SQL Tuning - Explain Plan Lies?
 
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Do you use EXPLAIN PLAN to tune Oracle SQL? Does it always "tell the truth", or does it "lie". (Maybe it's not the whole truth!) In this free tutorial from SkillBuilders' Oracle Certified Master John Watson, you will learn why the execution plan generated by EXPLAIN PLAN can be misleading and what to do about it. After a brief lecture, John demonstrates exactly why. You'll hear about dynamic sampling, adaptive cursor sharing (11g), adaptive execution plans (12c) and of course, bind variables. John demonstrates how bind variables cause misleading execution plans using dbms_xplan.display and dbms_xplan.display_cursor. To get the most from this tutorial, you should have some understanding of hard parse, soft parse, cardinality, histograms. See all SkillBuilders FREE Oracle Database tutorials at http://www.skillbuilders.com/free-oracle-tutorials.
Views: 3303 SkillBuilders
SQL: WITH Clause
 
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In this tutorial, you'll learn will learn how to use with clause PL/SQL (Procedural Language/Structured Query Language) is Oracle Corporation's procedural extension for SQL and the Oracle relational database. PL/SQL is available in Oracle Database (since version 7), TimesTen in-memory database (since version 11.2.1), and IBM DB2 (since version 9.7).[1] Oracle Corporation usually extends PL/SQL functionality with each successive release of the Oracle Database. PL/SQL includes procedural language elements such as conditions and loops. It allows declaration of constants and variables, procedures and functions, types and variables of those types, and triggers. It can handle exceptions (runtime errors). Arrays are supported involving the use of PL/SQL collections. Implementations from version 8 of Oracle Database onwards have included features associated with object-orientation. One can create PL/SQL units such as procedures, functions, packages, types, and triggers, which are stored in the database for reuse by applications that use any of the Oracle Database programmatic interfaces. PL/SQL works analogously to the embedded procedural languages associated with other relational databases. For example, Sybase ASE and Microsoft SQL Server have Transact-SQL, PostgreSQL has PL/pgSQL (which emulates PL/SQL to an extent), and IBM DB2 includes SQL Procedural Language,[2] which conforms to the ISO SQL’s SQL/PSM standard. The designers of PL/SQL modeled its syntax on that of Ada. Both Ada and PL/SQL have Pascal as a common ancestor, and so PL/SQL also resembles Pascal in several aspects. However, the structure of a PL/SQL package does not resemble the basic Object Pascal program structure as implemented by a Borland Delphi or Free Pascal unit. Programmers can define public and private global data-types, constants and static variables in a PL/SQL package.[3] PL/SQL also allows for the definition of classes and instantiating these as objects in PL/SQL code. This resembles usage in object-oriented programming languages like Object Pascal, C++ and Java. PL/SQL refers to a class as an "Abstract Data Type" (ADT) or "User Defined Type" (UDT), and defines it as an Oracle SQL data-type as opposed to a PL/SQL user-defined type, allowing its use in both the Oracle SQL Engine and the Oracle PL/SQL engine. The constructor and methods of an Abstract Data Type are written in PL/SQL. The resulting Abstract Data Type can operate as an object class in PL/SQL. Such objects can also persist as column values in Oracle database tables. PL/SQL is fundamentally distinct from Transact-SQL, despite superficial similarities. Porting code from one to the other usually involves non-trivial work, not only due to the differences in the feature sets of the two languages,[4] but also due to the very significant differences in the way Oracle and SQL Server deal with concurrency and locking. There are software tools available that claim to facilitate porting including Oracle Translation Scratch Editor,[5] CEITON MSSQL/Oracle Compiler [6] and SwisSQL.[7] The StepSqlite product is a PL/SQL compiler for the popular small database SQLite. PL/SQL Program Unit A PL/SQL program unit is one of the following: PL/SQL anonymous block, procedure, function, package specification, package body, trigger, type specification, type body, library. Program units are the PL/SQL source code that is compiled, developed and ultimately executed on the database. The basic unit of a PL/SQL source program is the block, which groups together related declarations and statements. A PL/SQL block is defined by the keywords DECLARE, BEGIN, EXCEPTION, and END. These keywords divide the block into a declarative part, an executable part, and an exception-handling part. The declaration section is optional and may be used to define and initialize constants and variables. If a variable is not initialized then it defaults to NULL value. The optional exception-handling part is used to handle run time errors. Only the executable part is required. A block can have a label. Package Packages are groups of conceptually linked functions, procedures, variables, PL/SQL table and record TYPE statements, constants, cursors etc. The use of packages promotes re-use of code. Packages are composed of the package specification and an optional package body. The specification is the interface to the application; it declares the types, variables, constants, exceptions, cursors, and subprograms available. The body fully defines cursors and subprograms, and so implements the specification. Two advantages of packages are: Modular approach, encapsulation/hiding of business logic, security, performance improvement, re-usability. They support object-oriented programming features like function overloading and encapsulation. Using package variables one can declare session level (scoped) variables, since variables declared in the package specification have a session scope.
Views: 12229 radhikaravikumar

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