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Search results “Oracle cost and cardinality”
What is Cardinality and High Cardinality and Low Cardinality in Oracle
 
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What is Cardinality and High Cardinality and Low Cardinality in Oracle SQL Tutorial SQL Tutorial for beginners PLSQL Tutorial PLSQL Tutorial for beginners PL/SQL Tutorial PL SQL Tutorial PL SQL Tutorial for beginners PL/SQL Tutorial for beginners Oracle SQL Tutorial
Views: 1323 TechLake
Oracle Cost Based Optimizer Basics
 
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When it comes to writing efficient queries there are a few key concepts that need to be understood. One of them is the Oracle Cost-Based Optimizer (CBO). Although it's called a cost-based optimizer it's actually not the cost we need to focus on primarily to understand why the optimizer makes certain decisions. In this webinar, you will learn the basics of the CBO, see why it is crucial that the optimizer's picture of the data fits reality, why cardinality and selectivity estimates matter so muc
Views: 58917 Redgate Videos
Oracle SQL Tuning - How to Read Execution Plans (Explain Plan)
 
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In this free tutorial you will learn how to generate and read (interpret) an execution plan in Oracle Databases. See more FREE Oracle Tuning tutorials at http://skillbuilders.com/free-oracle-tutorials. Understanding what the Oracle Database does with your SQL is essential to tuning - and the execution plan is the key. Oracle Certified Master DBA John Watson will provide a brief introduction (4 minutes) - which includes John's tuning methodology, then demonstrate EXPLAIN PLAN, SQL*Plus AUTOTRACE and DBMS_XPLAN.DISPLAY_CURSOR. In the tutorial, John will teach you: - How to read an execution plan - Find the 1st step in the plan - Decipher the order of the steps in the plan - That EXPLAIN PLAN can be very misleading Prerequisites: To get the most from this tutorial, you should: 1 Know how to code SQL 2 Be familiar with SQL*Plus 3 Know - in very general terms - what an execution plan is. 4 Have a basic understanding of the Library Cache (this is where Oracle Database stores parsed SQL statements) 5 Have a basic understanding of the Cost Based Optimizer (this is the part of the database that parses your SQL, creates an execution plan. Hopefully the correct - most efficient - plan).
Views: 67111 SkillBuilders
Oracle Database SQL Tuning with Constraints - Lesson 1 of 5
 
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Learn how to tune SQL - especially in Data Warehouse environments - with Constraints. Constraints provide critical information to the Cost Based Optimizer in the Oracle Database. Don't drop your constraints for query performance! In these 5 lessons, Oracle Certified Master DBA John Watson will demonstrate how constraints - unique, foreign key, not null - improve the execution plan and thus performance of SQL in an Oracle database. View all 5 lessons, free at http://www.skillbuilders.com/oracle-database-sql-tuning-with-constraints.
Views: 911 SkillBuilders
SQL Server Cardinality Estimation – Quick Notes – Part 1 by Amit Bansal
 
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In this video you will learn how the SQL Optimizer uses Density information to compute default cardinality estimations Twitter: http://www.twitter.com/SQLMaestros Twitter: http://www.twitter.com/A_Bansal http://www.SQLMaestros.com http://www.amitbansal.net
Views: 3162 SQLMaestros
Oracle SQL Tuning Re-Optimizing Execution Plans with Cardinality Feedback
 
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Cardinality feedback, introduced with Oracle Database 11g, has been significantly enhanced with 12c. Cardinality feedback allows the CBO to learn from a cardinality estimate mistake and re-optimize the execution plan. Learn more in this free SQL Tuning tutorial. See all free Oracle Database tutorials at http://www.skillbuilders.com/free-oracle-tutorials.
Views: 3221 SkillBuilders
Using Auto DOP, Part 1
 
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This video is the first in a two-part presentation on how to use the Auto DOP feature of Oracle Database 11g, Release 2. Copyright © 2012 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.
Oracle SQL Tuning - Equal SQL is not Always Equal
 
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Learn how and why equivalent SQL statements can have a dramatic effect on performance. Certified Master J Watson demonstrates...See all our free Oracle Database tutorials at http://skillbuilders.com/free-oracle-tutorials. The Oracle Database cost-based optimizer (CBO) should recognize equivalent SQL statements and re-write them into the most efficient form. Well, nothing is perfect - not even Oracle Database. Sometimes the way you write your SQL can have a dramatic effect on performance. Presented by John Watson, Oracle Certified Master DBA. Some experience with SQL tuning is expected.
Views: 1998 SkillBuilders
Oracle Optimizer Cost Calculation from explain plan
 
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This presentation describes the method to understand how oracle calculate cost during explain plan generation
Views: 737 debasis maity
Why Won't Oracle Use My Index - 12c Attribute Clustering - Lesson 1
 
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Sometimes a poor clustering factor is the cause when Oracle Database cost based optimizer does not choose to use an index. With Oracle 12c (12.1.0.2 EE) offers a new feature that can really help - "Atrribute Clustering". This is implemented with a new keyword on CREATE TABLE - "CLUSTERING BY LINEAR ORDER". In this Free Tutorial from SkillBuilders and Oracle Certified Master DBA John Watson, you'll get a brief refresher on clustering factor and a demonstration of CREATE TABLE - "CLUSTERING BY LINEAR ORDER" - so the CBO will use your index! In this first lesson, John will provide a brief review of clustering factor. See all 6 lessons - FREE - at http://www.skillbuilders.com/12c-attribute-clustering
Views: 398 SkillBuilders
15a  Index Selectivity
 
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Views: 85 B's March
ORACLE WORLD - Understanding Oracle Optimizer Statistics part-2nd
 
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Hello friends in this video i'm just showing to you what is optimizer statistics into oracle,optimizer help to improve the performance of sql statements during execution period. #ORACLEWORLD #OptimizerStatistics Oracle database Unbeatable,Unbreakable Platform.
Views: 2394 Oracle World
Statistics histogram Cardinality In simple word.
 
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The SQL Server query optimizer uses distribution statistics when creating a query plan. The statistics provide information about the distribution of column values across participating rows, helping the optimizer better estimate the number of rows, or cardinality, of the query results. Cardinality (SQL statements) In SQL (Structured Query Language), the term cardinality refers to the uniqueness of data values contained in a particular column (attribute) of a database table. The lower the cardinality, the more duplicated elements in a column
Views: 333 SqlIsEasy
07 07 Index Selectivity
 
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ORACLE
Views: 444 oracle ocm
Oracle Database 12c: Adaptive Execution Plans with Tom Kyte
 
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Tom Kyte introduces adaptive execution plans followed by a demo. "Adaptive Plans" in SQL Tuning Guide" http://www.oracle.com/pls/topic/lookup?ctx=db121&id=TGSQL221 "Controlling Adaptive Optimization" http://www.oracle.com/pls/topic/lookup?ctx=db121&id=TGSQL257 "Generating and Displaying SQL Execution Plans" http://www.oracle.com/pls/topic/lookup?ctx=db121&id=TGSQL271 "Keeping Your Database Secure" http://www.oracle.com/pls/topic/lookup?ctx=db121&id=DBSEG009
Views: 14277 OracleDBVision
Oracle 12c Dynamic Sampling
 
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Learn how to improve cardinality and performance of SQL statements with Oracle Database 12c Dynamic Sampling. For you Spinal Tap fans, you can now set it to "11".
Views: 996 SkillBuilders
SQL: Optimizer- RBO/CBO (Part-1)
 
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In this Tutorial, you will know what is RBO and the disadvantages of it..
Views: 11177 radhikaravikumar
12c Adaptive Optimization - Kerry Osborne
 
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One of the most interesting new features of the Oracle Database Optimizer is the ability to recognize its own mistakes and use execution statistics to automatically improve execution plans. Oracle calls this "Adaptive Optimization" and this talk will focus on how it works. More webinars at: http://www.red-gate.com/oracle-webinars
Views: 7144 Redgate Videos
14  Index Cardinality
 
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Views: 48 B's March
Getting Better Query Plans by Improving SQL’s Estimates by Brent Ozar
 
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You’ve been writing T-SQL queries for a few years now, and when you have performance issues, you’ve been updating stats and using OPTION (RECOMPILE). It’s served you well, but every now and then, you hit a problem you can’t solve. Your data’s been growing larger, your queries are taking longer to run, and you’re starting to wonder: how can I start getting better query plans? The secret is often comparing the query plan’s estimated number of rows to actual number of rows. If they’re different, it’s up to you – not the SQL Server engine – to figure out why the guesses are wrong. To improve ’em, you can change your T-SQL, the way the data’s structured and stored, or how SQL Server thinks about the data. This session won’t fix every query – but it’ll give you a starting point to understand what you’re looking at, and where to go next as you learn about the Cardinality Estimator. Get full session notes, slides, resources and more here: https://groupby.org/conference-session-abstracts/getting-better-query-plans-by-improving-sqls-estimates/
Views: 1251 GroupBy
SQL Tuning for Beginners Lesson 1 When and Why to Tune SQL
 
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Lesson 1 in this tuning tutorial Oracle Certified Master DBA John Watson discusses when a SQL should be tuned and why. i.e. Don't waste your time tuning things that will not help.
Views: 810 SkillBuilders
Histograms Pre-12c and now
 
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Anju Garg is an Oracle Ace Associate with over 12 years of experience in IT Industry in various roles. Since 2010, she has been involved in teaching and has trained more than a hundred DBAs from across the world in various core DBA technologies like RAC, Data guard, Performance Tuning, SQL statement tuning, Database Administration etc. She is a regular speaker at Sangam and OTNYathra.  She also writes articles for All Things Oracle. She is passionate about learning and has keen interest in RAC and Performance Tuning. She shares her knowledge via her technical blog at http://oracleinaction.com/ ABSTRACT--- To improve optimizer estimates in case of skewed data distribution , histograms can be created. Prior to 12c frequency and height balanced histograms could be created.  if no. of buckets >= NDV, frequency histogram is created and the optimizer makes correct estimates. If no. of buckets < NDV, height balanced histogram is created and accuracy of optimizer estimates depends on whether a key value is an endpoint or not. The problem of optimizer misestimates in case of height balanced histograms is resolved to a large extent in Oracle Database 12c by introducing top-frequency and hybrid histograms which are created if no. of buckets < NDV. This webinar explores Pre as well post 12c histograms while highlighting the top-frequency and hybrid histograms introduced in Oracle Database 12c.
Reading Oracle SQL Execution Plans - Practice Makes Perfect
 
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To tune a SQL statement, you need to understand the execution plan. Can you identify the 1st step in an execution plan? The 2nd? The 3rd? In this short tutorial, Oracle Certified Master DBA John Watson of SkillBuilders uses a MERGE JOIN to help you understand how to find the order of execution, essential for SQL tuning.
Views: 1248 SkillBuilders
Optimizer Parameters in Oracle Database 18c.
 
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Oracle ACE Biju Thomas, principal solutions architect at OneNeck IT Solutions, shares a tip about optimizer parameters in Oracle Database 18c that he says will make life easier for developers. Check it out. Recorded at ODTUG Kscope 2018 in Orlando, Florida. https://developer.oracle.com/ https://cloud.oracle.com/en_US/tryit
Views: 100 Oracle Developers
scale.bythebay.io: Pavan, Druid Lookups for High Cardinality Dimensions
 
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Druid is a high-performance, column-oriented, distributed data store. Lookups are a concept in Druid where dimension values are (optionally) replaced with new values. The common use case of query-time lookups is to replace one dimension value (e.g. an ID) with another value (e.g. a human-readable Name). This is similar to a star-schema join. Druid has limited sup- port for joins through query-time lookups. Very small lookups (count of keys on the order of a few dozen to a few hundred) can be passed at query time as a "map" lookup as per dimension specs. For large lookups, Druid has an extension called Namespaced lookups. Namespaced lookups are appropriate for lookups that cannot be passed at query time due to their size, or are not desired to be passed at query time because the data is to reside in and be handled by the Druid servers. But Druid’s namespaced lookups has following limitations, • It is not suitable for high cardinality dimensions • It is not scalable for large data in the order of hundreds of millions of rows • Namespaced lookup support is limited to one key column with a corresponding value column • Real time updates to the lookup data is not possible These limitations encouraged us to develop a highly scalable, multi-column, configurable Druid lookup framework that supports real time updates on lookup data. Framework uses embeddable persistent key-value data store, kafka for messaging and HDFS for deep storage.
Views: 578 FunctionalTV
DB Statistics
 
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Views: 1384 chaitanya kumar
Why Did Your SQL Execution Plan Change? | Alfredo Krieg
 
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Oracle ACE Alfredo Krieg offers advice on tools for improving database performance in this 2 Minute Tech Tip recorded at the 2016 Great Lakes Oracle Conference in Cleveland, OH.
Views: 334 ArchBeat Archive
Oracle SQL Performance Tuning for Developers: Introduction
 
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This video is an introduction to Oracle SQL Performance Tuning for Developers: http://www.informit.com/store/oracle-sql-performance-tuning-for-developers-livelessons-9780134117027 6+ Hours of Video Instruction The focus of Oracle SQL Performance Tuning for Developers LiveLessons is to illustrate coding techniques that ensure a consistent response time between instances and releases of the Oracle database. This course works closely with performance tuning of actual SQL statements. Description In this video training, Dan Hotka starts out with a complete overview of the Oracle architecture so students can get an understanding how their SQL and applications can take advantage of the computing environment. This course then goes in-depth on understanding and controlling the Explain Plan, which is how and in what order Oracle retrieves data. The discussion includes considerable detail, with SQL examples, on how the optimizers--both rule-based and cost-based, but mostly cost-based--make their decisions. Students will work with a variety of SQL statements, reviewing Explain Plans and making changes to make these SQL statements perform better. Lectures include index design, using hints and coding style to control the Explain Plans, and how to use useful tools such as index monitoring, SQL Trace, and the PL/SQL profiler. This LiveLessons course takes a close look at indexes: how Oracle selects them, why they are sometimes not used, and how to tell if indexes are being used. This course includes Oracle10g, Oracle11g, and Oracle12c SQL tuning topics. Skill Level Intermediate Learn How To Read and understand Explain Plan content Review an Explain Plan and tell quickly if this is a good plan Understand a good index column candidate from a not-so-good candidate Quickly tell the likelihood if your SQL will use an existing index Use coding and a variety of Hints (directives) that can produce better performing SQL Execute and interpret SQL trace output Who Should Take This Course Oracle programmers Oracle database administrators who need additional training on SQL tuning Course Requirements Working knowledge of the SQL query language http://www.informit.com/store/oracle-sql-performance-tuning-for-developers-livelessons-9780134117027
Views: 3211 LiveLessons
Oracle SQL Performance Tuning for Developers: Understand Explain Plans
 
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Understanding Explain Plans is an excerpt from Oracle SQL Performance Tuning for Developers: http://www.informit.com/store/oracle-sql-performance-tuning-for-developers-livelessons-9780134117027 6+ Hours of Video Instruction The focus of Oracle SQL Performance Tuning for Developers LiveLessons is to illustrate coding techniques that ensure a consistent response time between instances and releases of the Oracle database. This course works closely with performance tuning of actual SQL statements. Description In this video training, Dan Hotka starts out with a complete overview of the Oracle architecture so students can get an understanding how their SQL and applications can take advantage of the computing environment. This course then goes in-depth on understanding and controlling the Explain Plan, which is how and in what order Oracle retrieves data. The discussion includes considerable detail, with SQL examples, on how the optimizers--both rule-based and cost-based, but mostly cost-based--make their decisions. Students will work with a variety of SQL statements, reviewing Explain Plans and making changes to make these SQL statements perform better. Lectures include index design, using hints and coding style to control the Explain Plans, and how to use useful tools such as index monitoring, SQL Trace, and the PL/SQL profiler. This LiveLessons course takes a close look at indexes: how Oracle selects them, why they are sometimes not used, and how to tell if indexes are being used. This course includes Oracle10g, Oracle11g, and Oracle12c SQL tuning topics. Skill Level Intermediate Learn How To Read and understand Explain Plan content Review an Explain Plan and tell quickly if this is a good plan Understand a good index column candidate from a not-so-good candidate Quickly tell the likelihood if your SQL will use an existing index Use coding and a variety of Hints (directives) that can produce better performing SQL Execute and interpret SQL trace output Who Should Take This Course Oracle programmers Oracle database administrators who need additional training on SQL tuning Course Requirements Working knowledge of the SQL query language http://www.informit.com/store/oracle-sql-performance-tuning-for-developers-livelessons-9780134117027
Views: 3478 LiveLessons
Simplified DBA-023-01-SQL Plan Management   EXPLAIN PLAN
 
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Optimizer needs statistics to create an execution plan for each query.
Oracle SQL Tuning with Unique Constraints
 
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Learn how to tune SQL with Constraints! In this lesson (4 of 5), OCM John Watson from SkillBuilders demonstrates how to improve query performance by adding not null constraints. See all lessons, free at http://www.skillbuilders.com/oracle-database-sql-tuning-with-constraints.
Views: 292 SkillBuilders
Using Parallel and Cardinal Hint
 
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This is a demo on using Parallel and Cardinal Hint to tune queries in ILM.
Views: 1330 Informatica Support
Oracle Star Transformation
 
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Oracle Star Transformation
Views: 246 The Silent DBA
SQL Tuning with Oracle Database 12c Histograms
 
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Learn the new 12c options for creating histograms. See all free video tutorials at http://www.skillbuilders.com/free-oracle-tutorials. In this free tutorial, Oracle Certified Master DBA John Watson demonstrates what histograms do (provide correct cardinality), the difference between histogram types (Frequency and Height Balanced). You will also learn the importance of the auto sample size algorithm in 12c and the new "Hybrid" and "Top Frequency" type histograms.
Views: 3784 SkillBuilders
How to Think Like the SQL Server Engine, Part 3: Statistics and Memory Grants
 
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Why does one query get wildly different execution plans? Learn how statistics influence your query plans, discover how to see your own statistics, and understand how stats help build memory grants.
Views: 6894 Brent Ozar Unlimited
Nested Loop Join in SQL Server by Satya Ramesh
 
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In this video, you will learn about basics around Nested Loop join and how Nested Loop Join algorithm works. You will also learn about different scenarios where SQL Server decides to use Nested Loop Join operator and how it affects performance. Video resources including presentation, demo files, code snippets and more learning material is available on http://www.dataplatformgeeks.com/ (Join for free and access all the resources) Connect with The Speaker (Satya Ramesh) -Follow on Twitter: https://twitter.com/satyaramesh230 -Follow on FaceBook at https://www.facebook.com/satyaramesh230 -Follow on LinkedIN: https://www.linkedin.com/in/ramesh-sa... Connect with SQLMaestros: http://sqlmaestros.com/ -http://www.twitter.com/SQLMaestros -https://www.facebook.com/SQLMaestros -Email us: [email protected] Have technical questions? Join the largest SQL group on FB www.facebook.com/groups/theSQLGeeks Our LinkedIn group https://www.linkedin.com/groups/6753546 DataPlatformGeeks (DPG) Community Join the fastest growing community of data & analytics professionals Why Join DPG? http://www.dataplatformgeeks.com/ -Attend all events hosted by DPG, including SQLMaestros Special Events -Get access to free videos, labs, magazines and host of learning resources -Download all events & conference material -Learn new skills. Sharpen existing skills -Be part of Asia’s Largest Data/Analytics Community -Opportunity to be a regional mentor & speaker at our events -Immense technical & professional development Do you know about Data Platform Summit? http://www.DPS10.com
Views: 1515 SQLMaestros
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: 1624 SkillBuilders
Statistics and Query Plans
 
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If you want to tune queries, you have to look at query plans and you have to understand what they’re showing you. One thing people look for when tuning is “bad cardinality estimates”. If you’ve wondered what that means, and you want to understand how the optimizer uses statistics when creating a query plan, then join me for this session on statistics and query plans. We’ll set the stage with a review of what statistics are, then see how the optimizer uses them and where to find that “cardinality estimate” information in a plan. We’ll also cover the various ways statistics can be updated, explore what happens to plans when those updates occur, and ultimately you will see why understanding how it all works is critical when you’re troubleshooting performance issues. Expect lots of demos so you can truly understand what statistics are, how they're used, and why their management is so essential for good performance.
Views: 74 Sarah H
Partner Webcast – Managing Exadata with Oracle Enterprise Manager 12c - 25 Sep 2014
 
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Oracle Enterprise Manager 12c is system management software that delivers centralized monitoring, administration, and life cycle management functionality for the complete Oracle IT infrastructure, including engineering systems. With a broad set of end-to-end monitoring, administration, configuration management, provisioning, and security capabilities, Enterprise Manager Cloud Control reduces the cost and complexity of managing computing environments. Oracle EM12c is using a holistic approach to manage Oracle Exadata Database Machine allowing administrators to monitor and manage Exadata hardware and software from single console. Presenter: Alexey Kotelnitzky – EM Specialist, FORS Distribution | FORS Group Oracle Partner Hub Migration Center Russia (http://blogs.oracle.com/imc) [Read More @ https://blogs.oracle.com/imc/entry/managing_exadata_with_em_12c]
Views: 1297 Oracle IMC
Oracle Database 12c Security - Oracle Virtual Private Database (VPD)
 
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Learn how to use Oracle Virtual Private Database (VPD) to secure your data. See all lessons at http://skillbuilders.com/12c-TSDP-Tutorial First, Virtual Private Database. What is it? Answer: It's a declarative technique for enforcing security. Typically, it's based on user application context. That was the first limitation of 8i. Backed with 8i context were session-specific. The context variables were sort in the PGA. That means you simply couldn't use this in a web environment. However, global context, with use of 9i, Virtual Private Database became usable for web applications with connection pooling. But whether you're using it to client server or on a three tier environment, it's declarative technique rather than a programmatic technique. I can go behind the back of the application as a DBA and generate predicates to get appended to all SQLs. Select, insert, update, delete the end users. Issue the SQL and I will generate a predicate that filters the access. It's impossible to bypass. All users will have predicates appended to all their code. It doesn't matter whether they're using SQL Plus, Discoverer, Business Objects, Crystal Reports, eBusiness Suites, whatever they're using, I as DBA can filter their access to roles. The end result, different users see different data sets while running the same code and accessing the same tables, hence, the name Virtual Private Database. Different users will think they're seeing a totally different set of tables, but in fact it's one column database, one set of tables hosting a single application shared by all the users. The mechanism - you can apply VPD to tables, to views, to synonyms, and a declarative technique. Once the technique you write a function that generates the predicate, you associate the function with the table. From then on whenever the user issue SQL against that table the Cost-Based Optimizer rewrites the code. The Cost-Based Optimizer rewrites the user SQL to call the function to generate the predicate. The predicate is then appended to the SQL and it's the modified SQL that is parsed and executed. Let's see how this actually works. I'm working here by the way. This is just a perfectly normal 12.1 database. But what I'm going to demonstrate at this point will in fact work on 11g as well. I'm not going to be using any of the 12c enhancements to VPD for this little demonstration. I'll work in the scott schema. What do we have to do? We write a function to generate the predicate string. Create function. And I'll my function vpdf. The function must conform to a fixed specification. It must take two varchar arguments. One of the arguments is intended to be the schema to which the function will be applied. The other argument is the object within the schema to which the function will be applied. And it must return a varchar2, which is the generated predicate. Let's begin. Within this function you can do just about anything. There are some limitations. It's impossible for the function to query or update the table against which the VPD calls here is going to be applied or we violate the rules of purity that we come across so often with PL/SQL. But apart from that, it can do just about anything - including a number of dreadful side effects can be introduced by writing VPD functions. I'm going to do a very simple one on this one. I'll shall simple return immediately a predicate. What predicate? Ename, which is the ename column from this scott.emp table. Ename should equal sys_context. I'll go to the local context, my user end context, and just extract session user. We can see that John has tested this earlier today and therefore the object already was suggesting and he's just dropping it now and cleaning up the recreate. I hope you realize these really are live demonstrations. I'm not just running scripts. I've created a function. What's that function going to do? It's going to return this value here. Test it. Always test it and see what it's actually going to do. I'll select vpdf. I have to give it a couple of arguments. This one will do for now.
Views: 4626 SkillBuilders
SQL Saturday Israel: "Analyzing Execution Plans Like a Pro" by Guy Glantser
 
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Session language: Hebrew The most powerful tool when tuning a query is the execution plan. In most cases, by analyzing the execution plan of a query, you can learn all you need to know about how the query processor has chosen to execute the query, what is causing the execution to take so long, and what you can do in order to make it run faster. But there are common pitfalls that you should be aware of when analyzing an execution plan, such as the fact that the operator cost values are always estimated, or the true meaning of the cardinality numbers within some of the plan operators. These pitfalls can be very misleading, and they might lead you to spend your tuning effort in the wrong direction. By understanding these pitfalls and avoiding them, you can save a lot of time and effort. You’ll become a performance tuning hero by getting the slow queries to run faster – faster… Slides & Demos: http://www.sqlsaturday.com/623/Sessions/Details.aspx?sid=59638
Oracle Database 11g: SQL Tuning Workshop
 
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'עמי אהרונוביץ, מנהל תחום אורקל בג'ון ברייס מכללת הי-טק, יו"ר ארגון משתמשי אורקל בישראל. מייסד ומנכ"ל DBACES , מציג את הקורס לשיפור ביצועים בסיבת אורקל - SQL TUNING למפתחים ולמנהלי בסיס נתונים. לפרטים נוספים על הקורס הקליקו כאן:http://bit.ly/17kSIYj בואו להיות חברים שלנו בפיסבוק : http://on.fb.me/J6Ru6b
Views: 238 JohnBryceTraining
Cost Based Optimizer Framework for Spark SQL: Spark Summit East talk by Ron Hu/Zhenhua Wang
 
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In Spark SQL’s Catalyst optimizer, many rule based optimization techniques have been implemented, but the optimizer itself can still be improved. For example, without detailed column statistics information on data distribution, it is difficult to accurately estimate the filter factor, cardinality, and thus output size of a database operator. With the inaccurate and/or misleading statistics, it often leads the optimizer to choose suboptimal query execution plans. We added a Cost-Based Optimizer framework to Spark SQL engine. In our framework, we use Analyze Table SQL statement to collect the detailed column statistics and save them into Spark’s catalog. For the relevant columns, we collect number of distinct values, number of NULL values, maximum/minimum value, average/maximal column length, etc. Also, we save the data distribution of columns in either equal-width or equal-height histograms in order to deal with data skew effectively. Furthermore, with the number of distinct values and number of records of a table, we can determine how unique a column is although Spark SQL does not support primary key. This helps determine, for example, the output size of join operation and multi-column group-by operation. In our framework, we compute the cardinality and output size of each database operator. With reliable statistics and derived cardinalities, we are able to make good decisions in these areas: selecting the correct build side of a hash-join operation, choosing the right join type (broadcast hash-join versus shuffled hash-join), adjusting multi-way join order, etc. In this talk, we will show Spark SQL’s new Cost-Based Optimizer framework and its performance impact on TPC-DS benchmark queries.
Views: 958 Spark Summit
Database and Its Applications Full Course | Introduction to Database Management System
 
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Database and Its Applications Full Course | Introduction to Database Management System | Tutorial on SQL | E-R Model and Data Models Data Base Applications Unit Introduction: This unit introduces the term database, its types, and its advantages. It also focuses on basic structure and elements of database. At the end provide solid concept of entities. Unit No. 1 Database Foundation Introduction, Data and Information, Components, Advantages Data Association, Entities, Keys and Its Types, Attributes Data Associations, Data Structure Diagram Unit No. 2 E-R Model and Data Models Basic constructs (Symbols), Degree of Relationships, Cardinality, and Gerund Modeling Time Dependent Data, Super Types, Sub types Hierarchical, Network, Relational, Comparison of All Data Models Relations, Characteristics of relation, Converting E-R Model into Relation Unit. No. 3 Normalization (1NF, 2NF, 3NF) Unit No. 4 Data Base Design (Conceptual Design, Physical Design) Unit No. 5 SQL Introduction Introduction, Creating, Altering & Deleting Table Inserting, Updating, & Deleting Rows, Querying the Tables SQL Functions Arithmetic, Group (Average, Count, Max, Min, Sum) Date, Special Functions (In, Between, Like, Null) Unit No. 6 Introduction to Forms Form Components, Form Module, Blocks, Items, Objects, Object Navigator Properties Window, Layout Editor Unit No. 7 Basic Form Design Using Wizard for Form Design, Customizing a Form Defining Items Buttons, Check Boxes, Display items, List Items, Radio Groups, Text Items Creating LOV, Crating Master Detail Form Unit No. 8 Introduction to Reports Report Design Consideration Report Objects Basic Report Design Objectives Unit No. 1 Importance of Database Database Concepts Various Architectures of Database The Cost, Risk and Environment of Database Management System Difference between Data & Information The Concept of Entity, and Attributes Various Types of Attributes How Entities are recognized in an Entity Type How various types are associated with one another? Objectives of Unit No. 2 Architecture of entity relationship model Various types of relationship How the complexities of relationship are handled Effect of cardinality in relationship How multi value attributes are modeled How time dependent attributes are modeled Associative entity types are modeled Hierarchical data model Network data model Relational data model Why relational data model is in use? The basics of database design Recommended Books: Modern Data Base Management, by Jaffery A. Hoffer Oracle Developer 2000 by Michael Stowe Find us on Facebook: https://web.facebook.com/Computer-Education-for-All-1484033978567298 YouTube: https://www.youtube.com/channel/UCiV37YIYars6msmIQXopIeQ
SQL Tuning for Beginners 2 How SQL Executes
 
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Learn Oracle SQL Tuning. In this lesson (#2) OCM John Watson teaches the SQL Execution Cycle. See all FREE lessons at http://www.skillbuilders.com/sql-tuning-for-beginners-free-tutorial.
Views: 558 SkillBuilders
Cost Based Optimizer in Apache Spark 2 2 continues -  Zhenhua Wang &  Wenchen Fan
 
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Apache Spark 2.2 ships with a state-of-art cost-based optimization framework that collects and leverages a variety of per-column data statistics (e.g., cardinality, number of distinct values, NULL values, max/min, avg/max length, etc.) to improve the quality of query execution plans. Leveraging these reliable statistics helps Spark to make better decisions in picking the most optimal query plan. Examples of these optimizations include selecting the correct build side in a hash-join, choosing the right join type (broadcast hash-join vs. shuffled hash-join) or adjusting a multi-way join order, among others. In this talk, we'll take a deep dive into Spark's cost based optimizer and discuss how we collect/store these statistics, the query optimizations it enables, and its performance impact on TPC-DS benchmark queries. Talk contributors: Zhenhua Wang (Huawei Technologies) and Wenchen Fan (Databricks) Session hashtag: #SFdd2
Views: 738 Databricks

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