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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: 7443 The Magic of SQL
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: 5130 Tech Coach
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: 4510 SkillBuilders
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: 16992 SqlIsEasy
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: 112 DbVidya
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: 331 Tanel Poder
How To Flashback a Table to particular SCN in Oracle
 
08:38
How To Flashback a Table to particular SCN in Oracle
Views: 5700 Abbasi Asif
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: 6678 OnLinE ReSoUrCe
06 06 Index Full Scan Operations
 
03:27
ORACLE
Views: 746 oracle ocm
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: 89 DbVidya
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: 20524 Abbasi Asif
Improving performance of full table scans in Oracle - Hebrew - שיפור ביצועים של סריקת טבלה באורקל
 
10:29
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: 315 Eran Koren
What is Oracle Exadata Smart Scan (Demonstration)
 
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How does Oracle Exadata Smart Scan work? What is Smart Scan. How to insure Oracle is offloading work to the Storage Tier? Learn this and more in this demonstration by OC Master John Watson of SkillBuilders. See all 11 lessons in this tutorial at http://skillbuilders.com/exadata-tutorials. John Watson: I want to show you very briefly how offload Smart Scan or flow processing can actually function. I'm working here just in the little demonstration Scott schema. I'll enable auto tracing so that we can see the effect on execution plans, which will also show me whether offload processing is indeed possible. So it's a simple query. I'll use a function here to check that to get offloaded as well as the column selection and the row selection and column projection. We'll have a predicate. Right. So there is the statement. It returned these three scalar values, as you would expect. How was this actually executed? There was a select statement, then it was executed, table access full. That's the only way to run that statement given the index on that table because in the middle of this, we see the key word, "storage." That key word tells me that this statement could indeed be offloaded to the storage tier. Furthermore, we see down here in the predicate information, "storage." That key word again tells me that the row filtering could have been done by the storage tier. So what happened is that the storage tier did not return every block of the empty* table to the database buffer cache, where my session would then have had to extract these values. All it returned to the instance was these three scalar values directly into the PGA of my server process. Now, there's also the initcap function there. Was that offloadable or not? There is a view "Read our SQL fm letter data," and that will tell us for each function whether or not it can be offloaded. So, just select its name, whether it's offloadable. Declare offloadable as yes and put in a sort order as well, and we see that in the current release, there are 393 functions that can be offloaded. Which ones? All the typecasting functions, truncations, trims. These are functions that get executed millions of times an hour in many, many environments. Note here two particularly important ones, balloon filters. The offload capability for balloon filters allows us to offload joins or facts to dimension tables. Those two in star schemas can be offloaded. The function I used was, in fact, initcap. Just for completeness, we'll scroll through all of these and we'll see that initcap itself is an offloadable function, and there it is along with many others. There are two classes of function that cannot be offloaded, and those are the aggregation functions and the analytic functions. I mention them just for completeness. There's an architectural issue there because aggregations and analytics potentially require access to all rows in the table. The row might be distributed across a cell. So it's a technical issue why they can't be offloaded, but virtually, all other functions can be offloaded with terrific drops in CPU usage, and combining that with the reduction of data traffic into the instances will give us vast performance improvements.
Views: 3721 SkillBuilders
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: 1657 The Magic of SQL
What is a SQL table scan
 
02:01
What is a SQL table scan - Find out more explanation for : 'What is a SQL table scan' only from this channel. Information Source: google
Views: 5 atunakai7c
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: 2904 SkillBuilders
Calculate query performance with Explain Plan in Oracle PLSQL.
 
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Explain plan is a wonderful utility in Oracle PL SQL. It helps you to understand how much cost a query takes to perform based on indexed table or table without index. In this oracle tutorial a full description is given on a table containing huge number of rows first based on index on a column and then without index.
Views: 3599 Subhroneel Ganguly
Automatic Big Table Caching
 
07:03
This is the second of two demonstrations about In-Memory caching new features, introduced in Oracle Database 12.1.0.2. This one illustrates the Automatic Big Table caching feature enhancing the in-memory parallel query capabilities of the Oracle Database in both single instance and Oracle RAC environments. An optional section of the buffer cache, called the big table cache, is used to store data for serial and parallel table scans. Copyright © 2014 Oracle and/or its affiliates. Oracle® is a registered trademark of Oracle and/or its affiliates. All rights reserved. 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 of merchantability, fitness for a particular purpose, and non-infringement.
How Does the Phyiscal Location of Rows Affect Indexes?: Finding All the Red Sweets Part 2
 
09:25
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: 3043 The Magic of SQL
07 06 Index Skip Scan Operations
 
03:14
ORACLE
Views: 764 oracle ocm
Oracle Tuning Tutorial - Long Full Table Scans Part 5 of 5
 
02:44
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: 1563 SkillBuilders
Partitioning in Oracle - Performance Basics
 
28:35
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: 7412 Tech Coach
Heap Tables and Index Organized Tables in Oracle | Chris Saxon
 
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Chris Saxon, a database evangelist, developer advocate, and SQL specialist with Oracle, uses up his two minutes with a tip on using heap tables and index organized tables in Oracle Database.
Database Design 39 - Indexes (Clustered, Nonclustered, Composite Index)
 
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This video covers the basics of indexes. Indexing is an extremely important step of database design. Without Indexes database queries can take a substantial amount of time and hog system resources. The main two classifications of indexes are clustered and non-clustered indexes. Clustered indexes are usually the primary key and determine how the data is actually stored in the table. These are the fastest and most effective. Non-clustered indexes sort a reference to data that is still fast but doesn't actually determine how the data is structured. The best tip I can give you is to use indexes but don't over use them. Having loads of indexes on columns that are barely ever in a where clause or join can bog down the database. This is because every time the table is updated the index must also be updated! When a database looks through a table for certain where conditions on a column that does not have an index, it does an entire table scan. This is not a good practice for large databases (or even small databases but not as bad). With an index the database will do an index seek and quickly find the data you are looking for. Composite indexes consist of two or more columns within one index. Use these when you plan on using the two columns together for a database query WHERE clause. Learn more about indexes here: https://www.calebcurry.com/blogs/database-design/introduction-to-indexes Donate!: http://bit.ly/DonateCTVM2. Courses for Download: http://www.udemy.com/u/calebcurry/ (Use the coupon code "YouTubeDiscount" without the quotes) Facebook: http://www.facebook.com/CalebTheVideoMaker Google+: https://plus.google.com/+CalebTheVideoMaker2 Twitter: http://Twitter.com/calebCurry Subscribe (it's free!): https://www.youtube.com/channel/UCZUyPT9DkJWmS_DzdOi7RIA?sub_confirmation=1 Amazing Web Hosting - http://bit.ly/ccbluehost (The best web hosting for a cheap price!)
Views: 88757 Caleb Curry
Table Scan Turbo First Look
 
02:32
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Views: 5389 PokerNewbsuk
Scanning Full Scan method
 
02:34
Views: 48 Ann Mc
Oracle || Indexes Part-1 by dinesh
 
32:23
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Types of Indexes (A B-tree index,A bitmap index )
 
27:18
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.
Views: 27110 Oracle World
Oracle Exadata Smart Scan - Limitations and Best Practices
 
03:21
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: 1623 SkillBuilders
Oracle Database 12c OLTP Compression
 
15:42
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: 540 Dominic Giles
Oracle Hints Tutorial for improving performance
 
10:35
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: 4860 TechLake
Oracle Performance - Indexes
 
28:28
Oracle Performance - Indexes
Views: 256 The Silent DBA
B-Tree Indexes
 
04:33
In this video, I'd like to take a look at B-tree indexes and show how knowing them can help design better database tables and queries.
Indexing in Oracle :B-Tree,Bitmap Indexing
 
25:48
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: 10154 Tech Coach
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: 3055 SkillBuilders
Oracle Indexes - Live Demonstration
 
19:12
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: 2652 DWS Ltd
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: 1246 Tech Coach
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: 262 Oracle Developers
#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: 24 ODTUG
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: 5576 Tech Coach
Oracle Tutorial || Online Training || Adv Sql | Index Organized Table Part - 1 by basha
 
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DURGASOFT is INDIA's No.1 Software Training Center offers online training on various technologies like JAVA, .NET , ANDROID,HADOOP,TESTING TOOLS ,ADF,INFORMATICA,TABLEAU,IPHONE,OBIEE,ANJULAR JS, SAP... courses from Hyderabad & Bangalore -India with Real Time Experts. Mail us your requirements to [email protected] so that our Supporting Team will arrange Demo Sessions. Ph:Call +91-8885252627,+91-7207212428,+91-7207212427,+91-8096969696. http://durgasoft.com http://durgasoftonlinetraining.com https://www.facebook.com/durgasoftware http://durgajobs.com https://www.facebook.com/durgajobsinfo......
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: 1521 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: 39365 Manish Sharma
Oracle Performance Tips - Indexes
 
03:58
Learn about index and types of indexes.
Views: 1973 Saurabh Kumar
What is High Water Mark(HVM) in oracle and how it effects the performance of queries?
 
05:41
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: 3113 Kishan Mashru

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