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A Story of Indexes and Full Table Scans: Finding All the Red Sweets Part 1
 
08:43
"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: 7712 The Magic of SQL
FTS vs Index Scan   Part 1
 
02:19
what is "full table scan in oracle" and "oracle index scan" Small Excerpt from "Oracle performance Tuning Session". http://www.dbvidya.com/oracle-performance-tuning-videos/ [email protected] +91 991 2323 000 Oracle Performance Tuning Online Training : http://www.dbvidya.com/course/performance-tuning-for-dba/ Oracle SQL Performance Tuning Training Online : http://www.dbvidya.com/course/sql-tuning-advanced/ Oracle Performance Tuning Videos Tutorial for DBA and Developers : http://www.dbvidya.com/oracle-performance-tuning-videos/ Oracle AWR Tutorial: http://www.dbvidya.com/course/oracle-awr/ Erwin Tool Online Training : http://www.dbvidya.com/course/erwin-tool/ ER Data Modeling Course : http://www.dbvidya.com/course/er-modeling/ Dimensional Modeling Training Online : http://www.dbvidya.com/course/dimensional-modeling/ Oracle Database Blogs : http://www.dbvidya.com/blog/
Views: 149 DbVidya
Indexes in Oracle :Index Scan Methods :Part 2
 
30:18
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: 5801 Tech Coach
FTS vs Index Scan  Part 2
 
01:59
Discusses "When Full table scan is recommended and when index scan is suggested" -small excerpt from "Oracle Performance tuning" http://www.dbvidya.com/blended-training/ [email protected] +91 991 2323 000 Oracle Performance Tuning Online Training : http://www.dbvidya.com/course/performance-tuning-for-dba/ Oracle SQL Performance Tuning Training Online : http://www.dbvidya.com/course/sql-tuning-advanced/ Oracle Performance Tuning Videos Tutorial for DBA and Developers : http://www.dbvidya.com/oracle-performance-tuning-videos/ Oracle AWR Tutorial: http://www.dbvidya.com/course/oracle-awr/ Erwin Tool Online Training : http://www.dbvidya.com/course/erwin-tool/ ER Data Modeling Course : http://www.dbvidya.com/course/er-modeling/ Dimensional Modeling Training Online : http://www.dbvidya.com/course/dimensional-modeling/ Oracle Database Blogs : http://www.dbvidya.com/blog/
Views: 109 DbVidya
What is Index Scan ,Index Seek and Table Scan?
 
06:34
An index scan or table scan is when SQL Server has to scan the data or index pages to find the appropriate records. index seek happens when data is searched among the index.Please watch full video for detail.
Views: 17870 SqlIsEasy
Oracle full table scans, direct path reads, object level checkpoints, ORA 8103s (old videos)
 
02:19:18
As the name says, in this hacking session I'll demo how full table scans (and full segment scans) work and related stuff too, like direct path read checkpoints and ORA-8103 errors.  It's an old video from 2011 so not with the best recording resolution, but should still be fun. As direct path reads go, some things have changed and should be clarified, perhaps the best explanation is here: https://blogs.oracle.com/smartscan-deep-dive/when-bloggers-get-it-wrong-part-1 https://blogs.oracle.com/smartscan-deep-dive/when-bloggers-get-it-wrong-part-2
Views: 394 Tanel Poder
Oracle Tuning Tutorial - Long Full Table Scans Part 1 of  5
 
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Learn SQL Tuning! Tune full table scans! Part 1 of 5 videos in this series. See all 5 tutorials, free, at http://www.skillbuilders.com/tuning-long-full-table-scans Number Eight in the "Performance tuning Guide, Top Ten Mistakes Found in Oracle Systems" Long Full Table Scans is described as follows: "Long full table scans for high-volume or interactive online operations could indicate poor transaction design, missing indexes, or poor SQL optimization. Long table scans, by nature, are I/O intensive and unscalable." Actually, there are many cases where the full table scan is your friend. But whether they are good or bad for the performance of the SQL that invokes them, there may be implications (for better or for worse) for performance of other statements. This is particularly true in 11.2.x, where direct reads are possible for serial scans, and indirect reads are possible for parallel scans. Do you trust the optimizer? The change in behaviour in recent releases may need some investigation, and revisiting older code. As always with a SkillBuilders Tutorial, we shall illustrate the issues and solutions with live demonstrations using release 11g (11.2.0.3). Audience: Operating System Administrators, Storage Administrators, Oracle Administrators and Management responsible for Storage and / or Oracle Databases.
Views: 2916 SkillBuilders
Oracle || Indexes Part-1 by dinesh
 
32:23
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Oracle Tuning Tutorial - Long Full Table Scans Part 2 of 5
 
06:33
See all 5 tutorials, free, at SkillBuilders.com/OracleTuningFullTableScans Number Eight in the "Performance tuning Guide, Top Ten Mistakes Found in Oracle Systems" Long Full Table Scans is described as follows: "Long full table scans for high-volume or interactive online operations could indicate poor transaction design, missing indexes, or poor SQL optimization. Long table scans, by nature, are I/O intensive and unscalable." Actually, there are many cases where the full table scan is your friend. But whether they are good or bad for the performance of the SQL that invokes them, there may be implications (for better or for worse) for performance of other statements. This is particularly true in 11.2.x, where direct reads are possible for serial scans, and indirect reads are possible for parallel scans. Do you trust the optimizer? The change in behaviour in recent releases may need some investigation, and revisiting older code. As always with a SkillBuilders Tutorial, we shall illustrate the issues and solutions with live demonstrations using release 11g (11.2.0.3). Audience: Operating System Administrators, Storage Administrators, Oracle Administrators and Management responsible for Storage and / or Oracle Databases.
Views: 4524 SkillBuilders
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: 40055 Manish Sharma
Scanning Full Scan method
 
02:34
Views: 49 Ann Mc
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: 266 Oracle Developers
Oracle Performance - Indexes
 
28:28
Oracle Performance - Indexes
Views: 263 The Silent DBA
Difference Between Delete and Truncate
 
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Below is link for Useful Pl/SQL Books http://goo.gl/XMy0tt ---------------------------------------------------------- Difference Between Delete and Truncate in Detail On bigger picture they serve the same purpose but there are many Differences listed with examples Point Delete Truncate 1. Data Recovery Delete: Come under the DML Category, we need to commit or Rollback explicitly to make the changes permanent, so we can recover the data by Rollback command fully with in a session or up to a point if Save Points are used Fall In DDL Category (DDL Command issue the Auto commit implicitly) so no chances of Recovery even not using the Flashback table method. But Truncate operations are also logged , they didn’t generate redo SQL but they are logged , view for truncated data info V$LOGMNR_CONTENTS 2. Data Removal Delete Can remove all or selected data using the Where Clause predicates. Or we can say delete any subset of rows We can Truncate complete table or a partition or sub partition of a table. 3. Speed Delete is Slower because oracle maintain the redo logs for Read Consistency (so that every session connected can see a consistent data at a given point of time ) Delete is very time consuming activity especially when table have numerous indexes and Triggers associated with table Faster as no data logs are maintained no associated trigger firing. 4. DML Triggers Firing DML (Delete) triggers associated with table will fire. DML Trigger will not fire in case of truncate method. 5. Flashback Technology Data can be recovered even after commit operation using Flashback Table options Flashback_transaction_query table will give what to recover and up to which point. Data cannot be recovered in truncate method by Flashback table option. 6. Referential Integrity Constraint Behavior if we don’t have related data in child table then we can delete the data from the parent table or we have variants like On Delete Cascade & on Delete set Null. We can’t truncate a table with enable Referential Integrity Constraint, even there is no data in the child table, we have to disable or drop the constraint if we want to truncate the table. Exception: Truncate is possible if the FK is self-referential means primary key and foreign key are on the same table. 7. Space De allocation or Space Utilization No extent reset with delete when deleting rows from a table, extents are not de allocated, So if there were 50 extents in the table before the deletion, there will still be 50 after the deletion. Truncate: When a table is truncated it will free the space allocated except in case of reuse storage clause. This space can subsequently be used only by new data in the table or cluster resulting from insert or update operations .All extents are de allocated leaving only the extents specified when the table was originally created .Example So if the table was originally created with min extents 3, there will be 3 extents remaining when the tables is truncated. When you truncate a table, NEXT is automatically reset to the last extent deleted. 8. High Water Mark Delete will not reset the high water mark Truncate will reset the High Water mark which is very important for performance point of view as in case of full table scan and full index scan oracle will read all the block under high water mark this makes a lot of difference in terms of performance. 9. Cluster No as such restriction with delete. You cannot individually truncate a table that is part of a cluster. You must truncate the cluster, Delete all rows from the table, or drop and re-create the table. 10. Information Capturing Delete : we can capture the row information what we have deleted using Delete Method, f you are deleting multiple records then use composite data types (collections & records) Truncate Don’t have this feature of capturing the deleted records. 11. Function Based Index Impact DELETE You cannot delete rows from a table if a function-based index on the table has become invalid. You must first validate the function-based index. Truncate: No as such restriction 12. UNUSABLE Indexes Delete no as such feature. Truncate if table is not empty then truncate make all unusable indexes to useable. 13. Complex views You cannot delete data from a Complex view except through INSTEAD OF triggers. But we can delete data from simple Views and MV. We cannot truncate a view simple or complex but you can truncate MV with special Features like Preserve MV Logs and Purge MV Logs. 14. Privileges Delete You need to provide delete table privilege on object. Truncate you must have drop table privilege there is no truncate table privilege exists. 15. Domain Index No as such restriction You cannot truncate the object having domain index in invalid or In progress state
Views: 12824 Ram Gupta
Improving performance of full table scans in Oracle - Hebrew - שיפור ביצועים של סריקת טבלה באורקל
 
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בסשן הזה אני מציג כיצד ניתן לשפר ביצועים של סריקת טבלה (Full Table Scan) באורקל ומדגים כיצד זה בפועל מתבטא ומתבצע בסביבת ייצור אמיתית. נתוודע למושג ה-High Water Mark, החשיבות שלו בעת Full Table Scan והעובדה ש-DELETE לא משפיע עליו. נראה כיצד נוכל לזהות אם יש בלוקים ריקים ומיותרים שאנו קוראים בעת סריקת הטבלה וכיצד ניתן לפתור את הבעיה.
Views: 316 Eran Koren
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: 8134 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: 3120 The Magic of SQL
06 06 Index Full Scan Operations
 
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ORACLE
Views: 778 oracle ocm
Oracle Tuning Tutorial - Long Full Table Scans Part 5 of 5
 
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See all 5 tutorials, free, at SkillBuilders.com/OracleTuningFullTableScans. In summary, serial full table scans were always indirect before 11.2, parallel scans always direct before 11.2. These are the two critical parameters. That hidden parameter _serial_direct_read, remember, defaults to auto so your application may start behaving very differently as you upgrade from 11.2.01 or 11.2.02. Parallel_degree_policy, that defaults to manual. But again, it becomes an option when you go to 11.2 to enable the automatic facility which allows not only automatic tuning to the degree of parallelism but also enables the ability to make indirect reads when doing a full table scan.
Views: 1572 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: 2661 DWS Ltd
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: 6841 OnLinE ReSoUrCe
Types of Indexes (A B-tree index,A bitmap index )
 
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Hi guys today is very most important topic in oracle is INDEXES help to increase performance at the time of search and modification into table records. #TypesofIndexes #B-treeindex#bitmapindex
Views: 27720 Oracle World
Oracle Performance Tips - Indexes
 
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Learn about index and types of indexes.
Views: 2050 Saurabh Kumar
07 06 Index Skip Scan Operations
 
03:14
ORACLE
Views: 783 oracle ocm
Oracle Hints Tutorial for improving performance
 
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Oracle Hints Tutorial for improving performance APPEND PARALLEL JOIN INDEX NO_INDEX SELECT /*+ FIRST_ROWS(10) */ * FROM emp WHERE deptno = 10; SELECT /*+ ALL_ROWS */ * FROM emp WHERE deptno = 10; SELECT /*+ NO_INDEX(emp emp_dept_idx) */ * FROM emp, dept WHERE emp.deptno = dept.deptno; SELECT /*+ INDEX(e,emp_dept_idx) */ * FROM emp e WHERE e.deptno = 10; -- SELECT /*+ INDEX(scott.emp,emp_dept_idx) */ * FROM scott.emp; SELECT /*+ AND_EQUAL(e,emp_dept_idx) */ * FROM emp e; SELECT /*+ INDEX_JOIN(e,emp_dept_idx) */ * FROM emp e; SELECT /*+ PARALLEL_INDEX(e,emp_dept_idx , 8) */ * FROM emp e; SELECT /*+ LEADING (dept) */ * FROM emp, dept WHERE emp.deptno = dept.deptno; SELECT /*+ PARALLEL(8) CACHE (e) FULL (e) */ * FROM emp e ; SELECT /*+ PARALLEL FULL (e) */ * FROM emp e ; SELECT /*+ PARALLEL USE_MERGE (emp dept) */ * FROM emp, dept WHERE emp.deptno = dept.deptno; -- SORT Merge Join SELECT /*+ PARALLEL USE_HASH (emp dept) */ * FROM emp, dept WHERE emp.deptno = dept.deptno; -- Hash Join SELECT /*+ PARALLEL */ * FROM emp e ; INSERT /*+ APPEND */ INTO mytmp select /*+ CACHE (e) */ *from emp e; commit;
Views: 5539 TechLake
Oracle Indexes - Beginner
 
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Oracle Indexes - Beginner
Views: 64479 Chris Ostrowski
B*Tree Index Types (Indexes in Oracle-2)
 
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This video will cover different types of B-tree indexes: Descending index,Reverse key index,Key Compressed Index B-tree cluster index,Index Organized Table(IOT):
Views: 15320 Anindya Das
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: 2945 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: 11584 Tech Coach
07 03 Bitmap Indexes
 
06:43
ORACLE
Views: 7998 oracle ocm
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 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: 43662 DWS Ltd
Table Scan Turbo First Look
 
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Find out more at http://pokernewbsuk.info
Views: 5418 PokerNewbsuk
Creating  Managing  Droping Oracle Database Tablespaces
 
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Creating Managing Droping Oracle Database Tablespaces select tablespace_name,block_size,status,contents,logging from dba_tablespaces; create tablespace mytbs datafile 'd:\oradata\dbrdbms\mytbs01.dbf' size 10m; alter tablespace mytbs add datafile 'd:\oradata\dbrdbms\mytbs02.dbf' size 10m; alter tablespace mytbs drop datafile 'd:\oradata\dbrdbms\mytbs02.dbf'; desc v$datafile; desc ts#,name from v$datafile; select ts#,name from v$tablespace; select v$datafile.ts#,v$datafile.name,v$tablespace.name from v$datafile,v$tablespace where v$datafile.ts#=v$tablespace.ts# and v$tablespace.name='MYTBS'; alter database datafile 'd:\oradata\dbrdbms\mytbs01.dbf' resize 20m; ALTER DATABASE DEFAULT TABLESPACE mytbs; select ts#,name from v$tablespace; select ts#,name from v$datafile; select ts#,name from v$tablespace; drop tablespace mytbs; drop tablespace mytbs ialtncluding contents and datafiles; drop tablespace mytbs including contents and datafiles cascade; alter tablespace mytbs read only; alter tablespace mytbs read write; alter tablespace mytbs force logging; alter tablespace mytbs nologging; alter tablespace mytbs flashback on; alter tablespace mytbs flashback off; purge tablespace mytbs user myuser;
Views: 20792 Abbasi Asif
Joins in Oracle (SQL) Explained in detail with practical examples
 
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The video demonstrates what are the different types of joins and who they work in SQL. The tutorial is a little elaborate to make sure that you understand different kind of joins and where you should use which kind of join. The 5 Kind of joins explained are. 1. Inner join (Join or simple join) :- Rows that are common to both tables are returned as the output. 2. Left Outer join (Left join):- Returns all rows from the left table along with matching rows from the right table 3.Right Outer join (Right join):- Returns all rows from the right table along with matching rows from the left table 4.Full outer join (Full join) :- Returns all the records when there is a match in either left or right table. 5. Cartesian Join : (Join with no where condition)also known as a Cartesian product, is a join of every row of one table to every row of another table.
Views: 6147 Tech Coach
A Story of Index Only Scans: Finding all the Red Sweets Part 3
 
05:25
So far in the red candy series, Chris has compared using an index to a full table scan to access sweets from his table. In this video he asks a different question: What if you just want to count how many sweets are red? In this case the index holds all the information Oracle needs to answer the query. He shows how the optimizer is able to process this via an index only scan. Chris goes on to investigate index only scans further. He discusses how theses can provide better performance than queries accessing the table itself. He finishes by looking at the conditions necessary to enable these. ============================ 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: 1683 The Magic of SQL
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: 1729 Tech Coach
#Kscope16 Interview: Chris Saxon, Oracle Corporation
 
04:16
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: 24 ODTUG
Oracle Tutorial || Online Training || Adv Sql | Index Organized Table Part - 1 by basha
 
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DURGASOFT is INDIA's No.1 Software Training Center offers online training on various technologies like JAVA, .NET , ANDROID,HADOOP,TESTING TOOLS ,ADF,INFORMATICA,TABLEAU,IPHONE,OBIEE,ANJULAR JS, SAP... courses from Hyderabad & Bangalore -India with Real Time Experts. Mail us your requirements to [email protected] so that our Supporting Team will arrange Demo Sessions. Ph:Call +91-8885252627,+91-7207212428,+91-7207212427,+91-8096969696. http://durgasoft.com http://durgasoftonlinetraining.com https://www.facebook.com/durgasoftware http://durgajobs.com https://www.facebook.com/durgajobsinfo......
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: 3125 SkillBuilders
How To Flashback a Table to particular SCN in Oracle
 
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How To Flashback a Table to particular SCN in Oracle
Views: 5740 Abbasi Asif
Reference partitioning in Oracle 11g
 
09:50
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: 1406 Tech Coach
Oracle Database 12c OLTP Compression
 
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This short video uses swingbench to demonstrate that its possible to make excellent space savings of both the space needed to store rows and the associated indexes without compromising transaction performance. You can find out more information on Oracle Database compression in this white paper http://www.oracle.com/technetwork/database/options/compression/advanced-compression-wp-12c-1896128.pdf You can download the software used in this demonstration here http://www.dominicgiles.com/swingbench.html
Views: 563 Dominic Giles
What is High Water Mark(HVM) in oracle and how it effects the performance of queries?
 
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This video tutorial is to understand the concept of a High Water Mark or HVM of a oracle table, also it states the various changes in the HVM when we perform a insert, delete and Truncate operation on the table, and the video also informs why is the truncate operation more advisable and optimized then the delete operation.
Views: 3216 Kishan Mashru
B*Tree Index Fundamentals(Indexes in Oracle-1)
 
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Part -1 : Introduction to Indexes, B*Tree Indexes, Index scan methods. Part -2 : B*Tree Index Types(different types of B*Tree indexes) Part -3: Using B*Tree Indexes(When use B*Tree indexes, factors related to B*Tree Access) Part -4 : Index Organized Table Part -5 : Bitmap Indexes Part -6: Partitioned Indexes Part- 7: Other type of Indexes based on characteristics & use. Part -8: Managing Indexes
Views: 48828 Anindya Das
What is? - Advanced Compression in Oracle Database 12c
 
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Join Kevin Jernigan, as he talks about Advanced Compression in Oracle Database 12c. How it optimizes and makes I/O reads more efficient and increases throughput. ================================= For more information, see http://www.oracle.com/goto/oll 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.

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