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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: 3848 Tech Coach
A Story of Indexes and Full Table Scans: Finding All the Red Sweets Part 1
 
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"Why isn't Oracle using my index?!" is a common question people have when tuning SQL queries. In this episode Chris compares two methods for finding all the red candies from party bags he's prepared. He shows how these are like a full table scan and an index range scan. He goes on to compare the performance of these two approaches. He shows when a full table scan becomes more efficient than an index range scan and vice versa. ============================ 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: 6828 The Magic of SQL
07 06 Index Skip Scan Operations
 
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ORACLE
Views: 694 oracle ocm
Oracle Performance - Indexes
 
28:28
Oracle Performance - Indexes
Views: 239 The Silent DBA
Oracle SQL Tuning Expert Series - Understanding Indexes
 
01:32:30
Ross Leishman of DWS Ltd presents the principles of Understanding Indexes for SQL Tuning. The presentation includes an entertaining demonstration of Indexes featuring DWS Alumnus Jordan Thomas as a "Buffer Cache". DWS Ltd is a leading publicly listed Australian IT Services company, providing services to blue chip organisations since 1991. With a business philosophy based upon integrity, reliability and professional service delivery, DWS provides end to end IT solutions. www.dws.com.au
Views: 42841 DWS Ltd
Reverse Key Index :Types of Btree Index in Oracle
 
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Please subscribe to my new channel. https://www.youtube.com/c/AnIndianAbroadd The Videos explains how Reverse Btree Index works and in what condition they shall be used. Reverse Btree index are used to solve index block contention. You can't perform range scans in reverse btree Index.
Views: 1124 Tech Coach
How Does the Phyiscal Location of Rows Affect Indexes?: Finding All the Red Sweets Part 2
 
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In part one of the red candy series, Chris compared the efficiency of using a index range scan and full table scan to access data. He found that a full table scan was more efficient when fetching more rows than there are table blocks. This analysis made a big assumption however. It worked on the presumption that there was no correlation between the order of candies in the document and which the bags they were in. In this episode tests this assumption. Chris looks at how the physical order of rows in a table can affect the efficiency of indexes on it. He discusses how Oracle tracks this via the clustering factor. ============================ 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: 2918 The Magic of SQL
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: 242 Oracle Developers
Partitioning in Oracle Explained with Real project Examples : Introduction
 
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This Video series will explain partitioning and its use cases referencing real project examples from different domain. It will explain what when and why of partitioning in a simple but elaborate manner. This is the 1st video which explains why partitioning is required and what are the advantages we gain from it. The following videos will explain when should we do it and how.
Views: 14283 Tech Coach
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: 7621 Tech Coach
Indexing
 
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My book "Patterns in Data Management" is now available both as an ebook or a print book (with color graphics!). See: http://amzn.to/1Ts3rwx This book is not a standard textbook on database techniques. This book was written extending and complementing preexisting educational videos (including this one). overview about playlist "Indexing" which you can find here: http://www.youtube.com/playlist?list=...
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: 6015 Tech Coach
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: 2515 Tech Coach
SQL tutorial 62: Indexes In Oracle Database By Manish Sharma RebellionRider
 
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Watch and learn concepts of SQL Index In Oracle Database. In this tutorial you will learn about B-Tree Index and Function based Index. ------------------------------------------------------------------------ ►►►LINKS◄◄◄ Blog : Previous Tutorial ► ------------------------------------------------------------------------- ►►►Help Me In Getting A Job◄◄◄ ►Help Me In Getting A Good Job By Connecting With Me on My LinkedIn and Endorsing My Skills. All My Contact Info is Down Below. You Can Also Refer Me To Your Company Thanks ------------------------------------------------------------------------- Copy Cloud referral link || Use this link to join copy cloud and get 20GB of free storage https://copy.com?r=kb4rc1 -------------------------------------------------------------------------- ►Make sure you SUBSCRIBE and be the 1st one to see my videos! -------------------------------------------------------------------------- Amazon Wishlist: http://bit.ly/wishlist-amazon ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ►►►Find me on Social Media◄◄◄ Follow What I am up to as it happens on https://twitter.com/rebellionrider https://www.facebook.com/imthebhardwaj http://instagram.com/rebellionrider https://plus.google.com/+Rebellionrider http://in.linkedin.com/in/mannbhardwaj/ http://rebellionrider.tumblr.com/ http://www.pinterest.com/rebellionrider/ You can also Email me at for E-mail address please check 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: 37900 Manish Sharma
Scanning Full Scan method
 
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Views: 48 Ann Mc
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: 3579 Tech Coach
How to think in SQL, a set-based mindset - Kevin Devine
 
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One of the main sticking points for developers when they need to write SQL is thinking about the process the incorrect way. Java, C# and others require procedural thinking for optimization, but SQL optimization requires a different tactic, set-based thinking. In this talk, Kevin Devine, takes you through a number of SQL scenarios that were originally written procedurally and shows you how they were optimized using set-based thinking. We will talk about optimizer decisions like full scan, index fast full scan, index range scan, hash joins, merge joins, nested loops anti semi joins, lazy spool, hash aggregate and more. In addition, we will examine the fallacy of process-oriented thinking for SQL and focus on results-oriented thinking. At the end of this talk, you should be able to look at SQL differently and go home ready to optimize those hard to understand queries. Copyright © 2015 Stir Trek Conference, Inc. All rights reserved. No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the publisher, except in the case of brief quotations embodied in critical reviews and certain other noncommercial uses permitted by copyright law.
Views: 3101 Stir Trek
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: 89821 radhikaravikumar
TestpassportのOracle Database 1Z0-064問題集は問題を解いている最適は思います
 
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http://www.testpassport.jp/Oracle-Database/1Z0-064.asp をご参照ください 1Z0-064認定試験を受験して資格を取得することを通して、彼らの知識やスキルを向上させます。 1Z0-064認定試験を基づいてもっと専門的な資格をもらて個人履歴を増やすため、受験する人が益々増えて来ました。 Testpassportは、世界で最も信頼性の高いOracle Database 1Z0-064認定トレーニング資料を持っており、それをあなたはあなたの素晴らしい計画を達成することができます。 Oracle Database 1Z0-064試験概要: 試験番号:1Z0-064 試験名称:Oracle Database 12c: Performance Management and Tuning 関連資格: Oracle Certified Expert, Oracle Database 12c: Performance Management and Tuning バージョン: Oracle Database 12c 試験時間:150 出題数: 84 合格ライン:62% 出題形式:Multiple Choice 試験料(税抜き): 26600 円 TestpassportのOracle Database 1Z0-064試験問題と解答はあなたが必要とした一切の試験トレーニング資料を準備して差し上げます。TestpassportのOracle Database 1Z0-064問題集のカバー率がとても高いですから、自分で勉強するよりずっと効率が高いです。 Oracle Database 1Z0-064試験の出題内容: Basic Tuning Diagnostics Using Automatic Workload Repository Using Metrics and Alerts Using Baselines Monitoring Real-Time Database Operation Using AWR-Based Tools Monitoring Applications Identifying Problem SQL Statements Influencing the Optimizer Reducing the Cost of SQL Operations Using SQL Performance Analyzer SQL Performance Management Using Database Replay Tuning the Shared Pool Tuning the Buffer Cache Tuning PGA and Temporary Space Using Automatic Memory Tuning I/O Using the Database Resource Manager 高い点数配分になっており、それらを落とすと合格率が下がるので、TestpassportのOracle Database 1Z0-064(Oracle Database 12c: Performance Management and Tuning)勉強資料の使用を必要があります。正確な1Z0-064練習問題集を選択をしたら、そんなに苦労しなくても成功することもできます。 弊社のOracle Database 1Z0-064無料サンプルを使用してから、認定試験をパスするのに自信を持っています。 1.You have been asked to use table compression for two large tables. Given are the details of the tables: The TRANS_DET table: - The table is used by an OLTP application. - High volume insert and update operations are performed on the table. - The table is frequently queried using index range scans. The TRANS_HISTORY table: - The table is used by a DSS application. - High volume bulk loads are performed on the table. - The table is used to store archival data on which large table full-table scans (FTS) are performed. Which row store compression would you recommend for these tables with minimal overhead on performance? (Choose the best answer.) A. basic table compression for both the tables B. advanced row compression for both the tables C. basic table compression for the TRANS_HISTORY table and advanced row compression for the TRANS_DET table D. basic table compression for the TRANS_DET table and advanced row compression for the TRANS_HISTORY table E. warehouse compression for the TRANS_DET table and archive compression for the TRANS_HISTORY table Answer: A 2.You want to generate statistics for new objects added to an OLTP application without affecting old statistics and the sessions that currently use them. Which two tasks would you perform to test the new statistics? (Choose two.) A. Set the OPTIMIZER_USE_PENDING_STATISTICS initialization parameter to TRUE for the session. B. Set the STALE_PERCENT statistics preference to zero and then gather statistics. C. Set the PUBLISH statistics preference to FALSE and then gather statistics. D. Use the DBMS_STATS.PUBLISH_PENDING_STATS procedure to make pending statistics the current statistics. E. Set the NO_INVALIDATE statistics preference to FALSE and gather statistics without affecting old statistics. Answer: A,B
Views: 4 深野晴美
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: 1398 Tech Coach
Chris Saxon - Finding All the Red M&Ms: A Story of Indexes and Full Table Scans
 
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'Why isn’t my query using an index?' is a common question people have when tuning SQL. This talk explores the factors that influence the optimizer’s decision behind this question. It does so by comparing fetching rows from a database table to finding all the red M&Ms from their bags. It contrasts using an index range scan and a full table scan to do this. It introduces the concepts of blocks and the clustering factor. It discusses how these affect the optimizer's calculations. It goes on to demonstrate how these concepts work in practice using real SQL queries. This session is intended for developers and DBAs who want to learn the basics of how the optimizer chooses between an index range or full table scan.
Views: 96 Riga Dev Days
BitMap Indexes & Examples
 
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BitMap Indexes & Examples watch more videos at https://www.tutorialspoint.com/videotutorials/index.htm Lecture By: Mr. Parth Panjab, Tutorials Point India Private Limited
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: 1587 SkillBuilders
Oracle Indexes - Live Demonstration
 
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When is a Full Table Scan faster than an Index Scan? Watch Ross and Jordan act out an Oracle database reading and caching data via both methods, explaining the costs and benefits in simple and easy to understand terms. The demonstration is part of a talk by Ross Leishman of DWS Ltd on the principles of Understanding Indexes for SQL Tuning. The full lecture is at this link: https://www.youtube.com/watch?v=Z4hKomnGHFA DWS Ltd is a leading publicly listed Australian IT Services company, providing services to blue chip organisations since 1991. With a business philosophy based upon integrity, reliability and professional service delivery, DWS provides end to end IT solutions. www.dws.com.au
Views: 2623 DWS Ltd
#Kscope16 Interview: Chris Saxon, Oracle Corporation
 
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http://kscope16.com http://kscope17.com To view Chris 's presentations go to http://odtug.com Finding All the Red M&Ms: A Story of Indexes and Full Table Scans Topic: Database - Subtopic: SQL “Why isn’t my query using an index?” is a common question people have when tuning SQL. This talk explores the factors that influence the optimizer’s decision behind this question. It does so by comparing fetching rows from a database table to finding all the red M&Ms from their bags. It contrasts using an index range scan and a full table scan to do this. It introduces the concepts of blocks and the clustering factor. It discusses how these affect the optimizer's calculations. It goes on to demonstrate how these concepts work in practice using real SQL queries. This session is intended for developers and DBAs who want to learn the basics of how the optimizer chooses between an index range or full table scan. SQL for Date Ranges and History Using Temporal Validity and Flashback Data Archive Topic: Database - Subtopic: SQL Keeping a full history of changes to a table is a common business requirement. Auditors and analysts often need to view data as it existed at some point in the past. This is to ensure regulation compliance or understand how the business is performing. This session discusses the challenges with writing the SQL to implement these requirements. It then introduces temporal validity and flashback data archive. It shows how you can use these features to simplify working with date ranges and history tables. This talk is for developers and/or DBAs who write SQL or build applications that use date ranges and/or capture past data.
Views: 22 ODTUG
1Z0-064 Oracle Database 12c: Performance Management and Tuning
 
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1Z0-064 Oracle Database 12c: Performance Management and Tuning http://exampasser.com/ExamPasser/ExamInfo.aspx?d=Oracle&c=1z0-064&q=1 USE THE CODE "FOE2013" TO GET 15% DISCOUNT
Views: 252 Exam Passer
Hash Partitioning in Oracle
 
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The Video explains Hash partitioning in oracle and how it focuses on equal data distribution. It explains how hash partitioning uses partition joins to improve performance in VLDB by MPP.
Views: 3201 Tech Coach
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: 6328 OnLinE ReSoUrCe
07 03 Bitmap Indexes
 
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ORACLE
Views: 6780 oracle ocm
What is BLOCK RANGE INDEX? What does BLOCK RANGE INDEX mean? BLOCK RANGE INDEX meaning
 
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What is BLOCK RANGE INDEX? What does BLOCK RANGE INDEX mean? BLOCK RANGE INDEX meaning - BLOCK RANGE INDEX definition - BLOCK RANGE 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 A Block Range Index or BRIN is a database indexing technique. They are intended to improve performance with extremely large tables. BRIN indexes provide similar benefits to horizontal partitioning or sharding but without needing to explicitly declare partitions. A BRIN is applicable to an index on a table that is large and where the index key value is easily sorted and evaluated with a MinMax function. BRIN were originally proposed by Alvaro Herrera of 2ndQuadrant in 2013 as 'Minmax indexes'. Implementations thus far are tightly coupled to internal implementation and storage techniques for the database tables. This makes them efficient, but limits them to particular vendors. So far PostgreSQL is the only vendor to have announced a live product with this specific feature, in PostgreSQL 9.5. Other vendors have described some similar features, including Oracle, Netezza 'zone maps', Infobright 'data packs', MonetDB and Apache Hive with ORC/Parquet. BRIN operate by "summarising" large blocks of data into a compact form, which can be efficiently tested to exclude many of them from a database query, early on. These tests exclude a large block of data for each comparison. By reducing the data volume so early on, both by representing large blocks as small tuples, and by eliminating many blocks, BRIN substantially reduce the amount of detailed data that must be examined by the database node on a row-by-row basis. Data storage in large databases is layered and chunked, with the table storage arranged into 'blocks'. Each block contains perhaps 1MB in each chunk and they are retrieved by requesting specific blocks from a disk-based storage layer. BRIN are a lightweight in-memory summary layer above this: each tuple in the index summarises one block as to the range of the data contained therein: its minimum and maximum values, and if the block contains any non-null data for the column(s) of interest. Unlike a traditional index which locates the regions of the table containing values of interest, BRIN act as "negative indexes", showing the blocks that are definitely not of interest and thus do not need to be processed further. Some simple benchmarks suggest a five-fold improvement in search performance with an index scan, compared to the unindexed table. Compared to B-trees, they avoid their maintenance overhead. As BRIN are so lightweight, they may be held entirely in memory, thus avoiding disk overhead during the scan. The same may not be true of B-tree: B-tree requires a tree node for every approximately N rows in the table, where N is the capacity of a single node, thus the index size is large. As BRIN only requires a tuple for each block (of many rows), the index becomes sufficiently small to make the difference between disk and memory. For a 'narrow' table the B-tree index volume approaches that of the table itself; the BRIN may be only 5-15% of it. A large database index would typically use B-tree algorithms. BRIN is not always a substitute for B-tree, it is an improvement on sequential scanning of an index, with particular (and potentially large) advantages when the index meets particular conditions for being ordered and for the search target to be a narrow set of these values. In the general case, with random data, B-tree may still be superior. A particular advantage of the BRIN technique, shared with Oracle Exadata's Smart Scanning, is in the use of this type of index with Big Data or data warehousing applications, where it is known that almost all of the table is irrelevant to the range of interest. BRIN allows the table to be queried in such cases by only retrieving blocks that may contain data of interest and excluding those which are clearly outside the range, or contain no data for this column. A regular problem with the processing of large tables is that retrieval requires the use of an index, but maintaining this index slows down the addition of new records. Typical practices have been to group additions together and add them as a single bulk transaction, or to drop the index, add the batch of new records and then recreate the index. Both of these are disruptive to simultaneous read / write operations and may not be possible in some continuously-operating businesses. With BRIN, the slowdown from maintaining the index is much reduced compared to B-tree. Wong reports that B-tree slowed down additions to an unindexed 10GB table by 85%, but a comparable BRIN only had an overhead of 11%. BRIN may be created for extremely large data where B-tree would require horizontal partitioning.....
Views: 153 The Audiopedia
Understanding Amibroker Templates and Chart ID for effective usage.
 
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If you are frequently using Amibroker templates then probably you would noticed that changing parameters in one chart will reflect the same on other charts which uses the same templates. While using the same templates for multiple charts amibroker chooses the same Chart ID. Chart ID is an index to AmiBroker’s internal chart table. So knowing the Chart ID, AmiBroker knows everything about the chart. The Chart ID uniquely identifies the chart.
Views: 1852 marketcalls
ROWID VS ROWNUM IN ORACLE
 
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This Video explains the difference between ROWID and ROWNUM using real project examples. ROWID provides the unique physical address where the row is being stored. ROWNUM indicates the order in which the data was returned from the select query.
Views: 1697 Tech Coach
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: 15963 SkillBuilders
When to use Oracle Database Bitmap Indexes Lesson 1
 
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This tutorial will identify some use cases for Oracle bitmap indexes, including some of the more advanced capabilities. See all lessons, free, at http://www.skillbuilders.com/when-to-use-oracle-bitmap-indexes. Indexing your Oracle Database for best performance? There are cases, depending on data structures and queries, where b-tree indexes are not useful (e.g. scan access paths perform inadequately). In these cases, bitmap indexes may be a better solution. Bitmap indexes are a powerful tool, but they need to be used with care. Inappropriate use may cause problems worse than those they solve. The tutorial covers somewhat more advanced cases such as using bitmap join indexes to denormalize a snowflake schema, and to enable star transformations in queries that join fact tables to several dimension tables. This training will benefit any Oracle DBA administering a Data Warehouse or VLDB and "power" developers working in same. Instructor: Oracle Certified Master DBA John Watson, SkillBuilders
Views: 395 SkillBuilders
Analysing Parallel Execution Skew - Using Diagnostics / Tuning Pack license
 
01:20:37
In this final part of the tutorial I show how to analyse Parallel Execution Skew if you happen to have a Diagnostics / Tuning Pack license. Having such a license can be very helpful for doing such an analysis, however the tools provided by Oracle still do have some shortcomings and bugs. These are demonstrated and finally I show how to perform such an analysis using my XPLAN_ASH utility that offers functionality not available out of the box from Oracle. It's advisable to watch the previous parts first: Part 1: https://www.youtube.com/watch?v=4YKDns1EyTw Part 2: https://www.youtube.com/watch?v=6BAiW6AwhfQ Part 3: https://www.youtube.com/watch?v=VPzUr9ofQwE If you're interested in reproducing the SQLs analysed here, you can find the scripts as part of the following blog post: http://oracle-randolf.blogspot.de/2014/04/analysing-parallel-execution-skew-data.html
Views: 511 Randolf Geist
Which Order Should Columns Go in an Index?: Finding All the Red Sweets Part 4
 
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When you create an index on multiple columns there's an important question you need to answer: In which order should you list the columns? This video looks at some of the factors you should consider to help answer this question. ============================ 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: 3480 The Magic of SQL
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: 957 Tech Coach
07 04 Index Column Order Matters
 
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ORACLE
Views: 50 oracle ocm
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: 526 The Audiopedia
14.316 Covering and Composite Index, Duplicates, Overflow Pages, Composite Keys
 
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Video for my inverted classroom "Database Systems". The complete list of videos and additional material is (will be) available at http://datenbankenlernen.de Computer Science, Saarland University: Bachelor (in German): http://www.cs.uni-saarland.de/index.php?id=52&L=1 Master (in English): http://www.cs.uni-saarland.de/index.php?id=132&L=1 Ph.D./Grad School: http://gradschool.cs.uni-saarland.de/
04 03 Contention and Latch Waits
 
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ORACLE
Views: 224 oracle ocm
SQL: Indexes - Bit Map & B-trees
 
09:16
In this tutorial, you'll learn when to use b-tree and bitmap index
Views: 50913 radhikaravikumar
Internals of Binary Tree Indexes
 
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Binary Tree Indexes 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: 16490 Oresoft LWC
Checkpoint Revalidate
 
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The REVALIDATE option regenerates the table headers for a partitioned table or uncompressed join index and optionally verifies and corrects the row partitioning for a table (but not for a join index) if you specify the WITH DELETE or WITH INSERT null partition handling options. You can specify the REVALIDATE option for unpartitioned tables and join indexes without also specifying PRIMARY INDEX. This makes revalidation applicable whether or not the table or join index has a primary index. You must specify the REVALIDATE option without also specifying PRIMARY INDEX for NoPI tables and column‑partitioned tables and join indexes. Otherwise, Teradata Database aborts the request and returns an error to the requestor. The REVALIDATE option also provides the ability to revalidate some data dictionary columns. REVALIDATE requests do not verify the column partitioning of a column‑partitioned table or join index. If partitioning errors are detected for a table (but not a join index), an ALTER TABLE REVALIDATE request corrects them. REVALIDATE also revalidates the following Data Dictionary table columns. wave web technology was established in 2012, and has a dynamic team of professional web developers, web designers, SEO experts and customer support . website : www.wavewebtech.com https://www.facebook.com/wavewebtechnologies https://twitter.com/wavewebtechnolo https://plus.google.com/collections/
Views: 5 vikas verma
File Operations - 03 Storage of Indexes and Partitions
 
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Connect with me or follow me at https://www.linkedin.com/in/durga0gadiraju https://www.facebook.com/itversity https://github.com/dgadiraju https://www.youtube.com/c/TechnologyMentor https://twitter.com/itversity
Views: 1164 itversity
Clustered and nonclustered indexes in sql server   Part 36
 
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In this video we will learn about 1. Different types of indexes in sql server 2. What are clustered indexes 3. What are NonClustered indexes 4. Difference between clustered and non clustered indexes Text version of the video http://csharp-video-tutorials.blogspot.co.uk/2012/09/clustered-and-non-clustered-indexes.html Slides http://csharp-video-tutorials.blogspot.com/2013/09/part-36-clustered-nonclustered-indexes.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 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
Views: 420020 kudvenkat
02 How to configure Rang partition In oracle database
 
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Now a days enterprises run databases of hundred of Gigabytes in size. These databases are known as Very Large Databases (VLDB). From Oracle Ver. 8.0 Oracle has provided the feature of table partitioning i.e. you can partition a table according to some criteria . For example you have a SALES table with the following structure Suppose this table contains millions of records, but all the records belong to four years only i.e. 1991, 1992, 1993 and 1994. And most of the time you are concerned about only one year i.e. you give queries like the following select sum(amt) from sales where year=1991; select product,sum(amt) from sales where year=1992 Group by product; Now whenever you give queries like this Oracle will search the whole table. If you partition this table according to year, then the performance is improve since oracle will scan only a single partition instead of whole table. This type of partitioning is useful when dealing with data that has logical ranges into which it can be distributed; for example, value of year. Performance is best when the data evenly distributes across the range
Views: 1716 OnLinE ReSoUrCe
Difference between rank dense rank and row number in SQL
 
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row_number vs rank vs dense_rank in sql server dense_rank vs rank vs row_number sql server rank dense_rank row_number in sql server In this video we will discuss the similarities and difference between RANK, DENSE_RANK and ROW_NUMBER functions in SQL Server. Similarities between RANK, DENSE_RANK and ROW_NUMBER functions Returns an increasing integer value starting at 1 based on the ordering of rows imposed by the ORDER BY clause (if there are no ties) ORDER BY clause is required PARTITION BY clause is optional When the data is partitioned, the integer value is reset to 1 when the partition changes SQL Script to create the Employees table Create Table Employees ( Id int primary key, Name nvarchar(50), Gender nvarchar(10), Salary int ) Go Insert Into Employees Values (1, 'Mark', 'Male', 6000) Insert Into Employees Values (2, 'John', 'Male', 8000) Insert Into Employees Values (3, 'Pam', 'Female', 4000) Insert Into Employees Values (4, 'Sara', 'Female', 5000) Insert Into Employees Values (5, 'Todd', 'Male', 3000) Notice that no two employees in the table have the same salary. So all the 3 functions RANK, DENSE_RANK and ROW_NUMBER produce the same increasing integer value when ordered by Salary column. SELECT Name, Salary, Gender, ROW_NUMBER() OVER (ORDER BY Salary DESC) AS RowNumber, RANK() OVER (ORDER BY Salary DESC) AS [Rank], DENSE_RANK() OVER (ORDER BY Salary DESC) AS DenseRank FROM Employees You will only see the difference when there ties. Now let's include duplicate values for Salary column. To do this First delete existing data from the Employees table DELETE FROM Employees Insert new rows with duplicate valuse for Salary column Insert Into Employees Values (1, 'Mark', 'Male', 8000) Insert Into Employees Values (2, 'John', 'Male', 8000) Insert Into Employees Values (3, 'Pam', 'Female', 8000) Insert Into Employees Values (4, 'Sara', 'Female', 4000) Insert Into Employees Values (5, 'Todd', 'Male', 3500) Notice 3 employees have the same salary 8000. When you execute the following query you can clearly see the difference between RANK, DENSE_RANK and ROW_NUMBER functions. SELECT Name, Salary, Gender, ROW_NUMBER() OVER (ORDER BY Salary DESC) AS RowNumber, RANK() OVER (ORDER BY Salary DESC) AS [Rank], DENSE_RANK() OVER (ORDER BY Salary DESC) AS DenseRank FROM Employees Difference between RANK, DENSE_RANK and ROW_NUMBER functions ROW_NUMBER : Returns an increasing unique number for each row starting at 1, even if there are duplicates. RANK : Returns an increasing unique number for each row starting at 1. When there are duplicates, same rank is assigned to all the duplicate rows, but the next row after the duplicate rows will have the rank it would have been assigned if there had been no duplicates. So RANK function skips rankings if there are duplicates. DENSE_RANK : Returns an increasing unique number for each row starting at 1. When there are duplicates, same rank is assigned to all the duplicate rows but the DENSE_RANK function will not skip any ranks. This means the next row after the duplicate rows will have the next rank in the sequence. Text version of the video http://csharp-video-tutorials.blogspot.com/2015/10/difference-between-rank-denserank-and.html Slides http://csharp-video-tutorials.blogspot.com/2015/10/difference-between-rank-denserank-and_2.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 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
Views: 36605 kudvenkat