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• What is Granularity?

  - by tonyrogerson

  Granularity defines “the lowest level of detail”; but what is meant by “the lowest level of detail”? Consider the Transactions table below: create table Transactions ( TransactionID int not null primary key clustered, TransactionDate date not null, ClientID int not null, StockID int not null, TransactionAmount decimal ( 28 , 2 ) not null, CommissionAmount decimal ( 28 , 5 ) not null ) A Client can Trade in one or many Stocks on any date – there is no uniqueness to ClientID, Stock and TransactionDate...(read more)

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• Would you expect this error ?

  - by GrumpyOldDBA

  Now I know why, but what I'm thinking is that if I create an error should I get valid data returned? To explain, I was browsing through the dmvs for queries which might benefit from tuning and I identified a query with two clustered index scans ( table scans ). I don't know all the schema off by heart and I was looking for a select by a LoginID column. I assumed this would be numeric and promptly entered an integer value to examine the query plan, yeah I should have looked at the table definition...(read more)

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• R2 download site is looking good

  - by DavidWimbush

  The MSDN downloads for R2 appeared as promised yesterday. Congratulations to everyone on the SQL team. I must have got one of the first downloads of the Developer Edition and it was nice and fast. I've just downloaded Standard Edition and it's still nearly as fast. Nice. I'm guessing they aren't using GUIDs for the clustered indexes this time! ;)

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• New Whitepaper: Oracle WebLogic Clustering

  - by ACShorten

  A new whitepaper is available that outlines the concepts and steps on implementing web application server clustering using the Oracle Utilities Application Framework and Oracle WebLogic Server. The whitepaper include the following: A short discussion on the concepts of clustering How to setup a cluster using Oracle WebLogic's utilities How to configure the Oracle Utilities Application Framework to take advantage of clustering How to deploy the Oracle Utilities Application based products in a clustered environment Common cluster operations The whitepaper is available from My Oracle Support at Doc Id: 1334558.1.

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• Manage and Monitor Identity Ranges in SQL Server Transactional Replication

  - by Yaniv Etrogi

  Problem When using transactional replication to replicate data in a one way topology from a publisher to a read-only subscriber(s) there is no need to manage identity ranges. However, when using  transactional replication to replicate data in a two way replication topology - between two or more servers there is a need to manage identity ranges in order to prevent a situation where an INSERT commands fails on a PRIMARY KEY violation error  due to the replicated row being inserted having a value for the identity column which already exists at the destination database. Solution There are two ways to address this situation: Assign a range of identity values per each server. Work with parallel identity values. The first method requires some maintenance while the second method does not and so the scripts provided with this article are very useful for anyone using the first method. I will explore this in more detail later in the article. In the first solution set server1 to work in the range of 1 to 1,000,000,000 and server2 to work in the range of 1,000,000,001 to 2,000,000,000.  The ranges are set and defined using the DBCC CHECKIDENT command and when the ranges in this example are well maintained you meet the goal of preventing the INSERT commands to fall due to a PRIMARY KEY violation. The first insert at server1 will get the identity value of 1, the second insert will get the value of 2 and so on while on server2 the first insert will get the identity value of 1000000001, the second insert 1000000002 and so on thus avoiding a conflict. Be aware that when a row is inserted the identity value (seed) is generated as part of the insert command at each server and the inserted row is replicated. The replicated row includes the identity column’s value so the data remains consistent across all servers but you will be able to tell on what server the original insert took place due the range that  the identity value belongs to. In the second solution you do not manage ranges but enforce a situation in which identity values can never get overlapped by setting the first identity value (seed) and the increment property one time only during the CREATE TABLE command of each table. So a table on server1 looks like this: CREATE TABLE T1 (  c1 int NOT NULL IDENTITY(1, 5) PRIMARY KEY CLUSTERED ,c2 int NOT NULL ); And a table on server2 looks like this: CREATE TABLE T1(  c1 int NOT NULL IDENTITY(2, 5) PRIMARY KEY CLUSTERED ,c2 int NOT NULL ); When these two tables are inserted the results of the identity values look like this: Server1:  1, 6, 11, 16, 21, 26… Server2:  2, 7, 12, 17, 22, 27… This assures no identity values conflicts while leaving a room for 3 additional servers to participate in this same environment. You can go up to 9 servers using this method by setting an increment value of 9 instead of 5 as I used in this example. Continues…

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• Efficient SQL Server Indexing by Design

  Having a good set of indexes on your SQL Server database is critical to performance. Efficient indexes don't happen by accident; they are designed to be efficient. Greg Larsen discusses whether primary keys should be clustered, when to use filtered indexes and what to consider when using the Fill Factor.

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• Implementing Cluster Continuous Replication, Part 3

  Cluster continuous replication (CCR) uses log shipping and failover to provide a more resilient email system with faster recovery. Once it is installed, a clustered server requires different management routines. These are done either with a GUI tool, The Failover Cluster Management Console, or the Exchange Management Shell. You can use Powershell as well for some tasks. Confused? Not for long, since Brien Posey is once more here to help.

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• SQL SERVER – Weekly Series – Memory Lane – #031

  - by Pinal Dave

  Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 Find Table without Clustered Index – Find Table with no Primary Key Clustered index is very important concept for any table. They impact the performance very heavily. Here is a quick script to find tables without a clustered index. Replace TEXT with VARCHAR(MAX) – Stop using TEXT, NTEXT, IMAGE Data Types Question: “Is VARCHAR (MAX) big enough to store the TEXT field?” Answer: “Yes, VARCHAR(MAX) is big enough to accommodate TEXT field. TEXT, NTEXT and IMAGE data types of SQL Server 2000 will be deprecated in a future version of SQL Server, SQL Server 2005 provides backward compatibility to data types but it is recommended to use new data types which are VARHCAR (MAX), NVARCHAR (MAX) and VARBINARY (MAX).” Limiting Result Sets by Using TABLESAMPLE – Examples Introduced in SQL Server 2005, TABLESAMPLE allows you to extract a sampling of rows from a table in the FROM clause. The rows retrieved are random and they are are not in any order. This sampling can be based on a percentage of number of rows. You can use TABLESAMPLE when only a sampling of rows is necessary for the application instead of a full result set. User Defined Functions (UDF) Limitations UDF have its own advantage and usage but in this article we will see the limitation of UDF. Things UDF can not do and why Stored Procedure are considered as more flexible then UDFs. Stored Procedure are more flexibility then User Defined Functions(UDF). However, this blog post is a good read to know what are the limitations of UDF. Change Database Compatible Level – Backward Compatibility For a long time SQL Server stayed on the compatibility level of 80 which is of SQL Server 2000. However, as soon as SQL Server 2005 introduced the issue of compatibility was quite a major issue. Since that time MS has been releasing the versions at every 2-3 years, changing compatibility is a ever popular topic. In this blog post, we learn how we can do the same using T-SQL. We can also do the same using SSMS and here is the blog post for the same: Change Database Compatible Level – Backward Compatibility – Part 2 – Management Studio. Constraint on VARCHAR(MAX) Field To Limit It Certain Length How can I limit the VARCHAR(MAX) field with maximum length of 12500 characters only. His Question was valid as our application was allowed 12500 characters. First of all – this requirement is bit strange but if someone wants to do the same, they can do it as described in this blog post. 2008 UNPIVOT Table Example Understanding UNPIVOT can be very complicated at times. In this blog post, I have attempted to explain the same concept in very simple words. Create Default Constraint Over Table Column A simple straight to script blog post – I still use this blog quite many times for my own reference. UDF – Get the Day of the Week Function It took me 4 iteration to find this very simple function which can immediately get the day of the week in a single line. 2009 Find Hostname and Current Logged In User Name There are two tricks listed in this blog post where users can find out the hostname and current logged user name immediately and very easily. Interesting Observation of Logon Trigger On All Servers When I was doing a project, I made an interesting observation of executing a logon trigger multiple times. It was absolutely unexpected for me! As I was logging only once, naturally, I was expecting the entry only once. However, it did it multiple times on different threads – indeed an eccentric phenomenon at first sight! Difference Between Candidate Keys and Primary Key One needs to be very careful in selecting the Primary Key as an incorrect selection can adversely impact the database architect and future normalization. For a Candidate Key to qualify as a Primary Key, it should be Non-NULL and unique in any domain. I have observed quite often that Primary Keys are seldom changed. I would like to have your feedback on not changing a Primary Key. Create Multiple Filegroup For Single Database Why should one create multiple file group for any database and what are the advantages of the same. In this blog post, I explain the same in detail. List All Objects Created on All Filegroups in Database In this blog post we discuss the essential question – “How can I find which object belongs to which filegroup. Is there any way to know this?” 2010 DATE and TIME in SQL Server 2008 When DATE is converted to DATETIME it adds the of midnight. When TIME is converted to DATETIME it adds the date of 1900 and it is something one wants to consider if you are going to run scripts from SQL Server 2008 to earlier version with CONVERT. Disabled Index and Update Statistics If you do not need a nonclustered index, I suggest you to drop it as keeping them disabled is an overhead on your system. This is because every time the statistics are updated for system all the statistics for disabled indexes are also updated. Precision of SMALLDATETIME – A 1 Minute Precision The precision of the datatype SMALLDATETIME is 1 minute. It discards the seconds by rounding up or rounding down any seconds greater than zero. 2011 Getting Columns Headers without Result Data – SET FMTONLY ON SET FMTONLY ON returns only metadata to the client. It can be used to test the format of the response without actually running the query. When this setting is ON the resultset only have headers of the results but no data. Copy Database from Instance to Another Instance – Copy Paste in SQL Server SQL Server has a feature which copy database from one database to another database and it can be automated as well using SSIS. Make sure you have SQL Server Agent Turned on as this feature will create a job. Puzzle – SELECT * vs SELECT COUNT(*) If you have ever wondered SELECT * gives error when executed alone but SELECT COUNT(*) does not. Why? in that case, you should read this blog post. Creating All New Database with Full Recovery Model This blog post is very based on very interesting story where the user wants to do something by default for every single new database created. Model database is a secret weapon which should be used very carefully and with proper evalution. If used carefully this can be a very much beneficiary when we need a newly created database behave in certain fashion. 2012 In year 2012 I had two interesting series ran on the blog. If there is no fun in learning, the learning becomes a burden. For the same reason, I had decided to build a three part quiz around SEQUENCE. The quiz was to identify the next value of the sequence. I encourage all of you to take part in this fun quiz. Guess the Next Value – Puzzle 1 Guess the Next Value – Puzzle 2 Guess the Next Value – Puzzle 3 Can anyone remember their final day of schooling?  This is probably a silly question because – of course you can!  Many people mark this as the most exciting, happiest day of their life.  It marks the end of testing, the end of following rules set by teachers, and the beginning of finally being able to earn money and work in your chosen field. Read five part series on developer training subject Developer Training - Importance and Significance - Part 1 Developer Training – Employee Morals and Ethics – Part 2 Developer Training – Difficult Questions and Alternative Perspective - Part 3 Developer Training – Various Options for Developer Training – Part 4 Developer Training – A Conclusive Summary- Part 5 Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• Northwind now available on SQL Azure

  - by jamiet

  Two weeks ago I made available a copy of [AdventureWorks2012] on SQL Azure and published credentials so that anyone from the SQL community could connect up and experience SQL Azure, probably for the first time. One of the (somewhat) popular requests thereafter was to make the venerable Northwind database available too so I am pleased to say that as of right now, Northwind is up there too. You will notice immediately that all of the Northwind tables (and the stored procedures and views too) have been moved into a schema called [Northwind] – this was so that they could be easily differentiated from the existing [AdventureWorks2012] objects. I used an SQL Server Data Tools (SSDT) project to publish the schema and data up to this SQL Azure database; if you are at all interested in poking around that SSDT project then I have made it available on Codeplex for your convenience under the MS-PL license – go and get it from https://northwindssdt.codeplex.com/. Using SSDT proved particularly useful as it alerted me to some aspects of Northwind that were not compatible with SQL Azure, namely that five of the tables did not have clustered indexes: The beauty of using SSDT is that I am alerted to these issues before I even attempt a connection to SQL Azure. Pretty cool, no? Fixing this situation was of course very easy, I simply changed the following primary keys from being nonclustered to clustered: [PK_Region] [PK_CustomerDemographics] [PK_EmployeeTerritories] [PK_Territories] [PK_CustomerCustomerDemo]   If you want to connect up then here are the credentials that you will need: Server mhknbn2kdz.database.windows.net Database AdventureWorks2012 User sqlfamily Password sqlf@m1ly You will need SQL Server Management Studio (SSMS) 2008R2 installed in order to connect or alternatively simply use this handy website: https://mhknbn2kdz.database.windows.net which provides a web interface to a SQL Azure server. Do remember that hosting this database is not free so if you find that you are making use of it please help to keep it available by visiting Paypal and donating any amount at all to [email protected]. To make this easy you can simply hit this link and the details will be completed for you – all you have to do is login and hit the “Send” button. If you are already a PayPal member then it should take you all of about 20 seconds! I hope this is useful to some of you folks out there. Don’t forget that we also have more data up there than in the conventional [AdventureWorks2012], read more at Big AdventureWorks2012. @Jamiet  AdventureWorks on Azure - Provided by the SQL Server community, for the SQL Server community!

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• How to test issues in a local development environment that can only be introduced by clustering in production?

  - by Brian Reindel

  We recently clustered an application, and it came to light that because of how we're doing SSL offloading via the load balancer in production it didn't work right. I had to mimic this functionality on my local machine by SSL offloading Apache with a proxy, but it still isn't a 1-to-1 comparison. Similar issues can arise when dealing with stateful applications and sticky sessions. What would be the industry standard for testing this kind of production "black box" scenario in a local environment, especially as it relates to clustering?

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• Find your HEAPS

  - by NeilHambly

  I will not go into a full discussion as to why you would want to convert HEAP into a Clustered table .. as there are plenty of resources out there that describe those elements and the relevant Pro's & Con's However you may just want to understand which database tables are of the HEAP variety and how many of them "percentage wise" exist in each of your Databases So here is a useful script I have (it uses the sp_msforeachDB to iterate through all DBs on an instance), that easily...(read more)

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• Updatable columnstore index, sp_spaceused and sys.partitions

  - by Michael Zilberstein

  Columnstore index in SQL Server 2014 contains 2 new important features: it can be clustered and it is updateable. So I decided to play with both. As a “control group” I’ve taken my old columnstore index demo from one of the ISUG (Israeli SQL Server Usergroup) sessions. The script itself isn’t important – it creates partition function with 7 partitions (actually 8 but one remains empty), table on it and populates the table with 63 million rows – 9 million in each partition. So I used the same script...(read more)

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• Efficient SQL Server Indexing by Design

  Having a good set of indexes on your SQL Server database is critical to performance. Efficient indexes don't happen by accident; they are designed to be efficient. Greg Larsen discusses whether primary keys should be clustered, when to use filtered indexes and what to consider when using the Fill Factor.

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• Twitter Feed

  - by ferhat

  new TWTR.Widget({ version: 2, type: 'search', search: 'ORCL_InfraRed', interval: 10000, title: 'Inside news and all the buzz about Sun x86 Clustered Systems.', subject: 'Oracle InfraRed', width: 'auto', height: 300, theme: { shell: { background: '#ff0000', color: '#ffffff' }, tweets: { background: '#ffffff', color: '#444444', links: '#1985b5' } }, features: { scrollbar: false, loop: true, live: true, hashtags: true, timestamp: true, avatars: true, toptweets: true, behavior: 'default' } }).render().start();

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• SQL SERVER GUID vs INT Your Opinion

  I think the title is clear what I am going to write in your post. This is age old problem and I want to compile the list stating advantages and disadvantages of using GUID and INT as a Primary Key or Clustered Index or Both (the usual case). Let me start a list by suggesting [...]...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• LAG function – practical use and comparison to old syntax

  - by Michael Zilberstein

  Recently I had to analyze huge trace – 46GB of trc files. Looping over files I loaded them into trace table using fn_trace_gettable function and filters I could use in order to filter out irrelevant data. I ended up with 6.5 million rows table, total of 7.4GB in size. It contained RowNum column which was defined as identity, primary key, clustered. One of the first things I detected was that although time difference between first and last events in the trace was 10 hours, total duration of all sql...(read more)

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• Defining Indexes with SQL Server 2005

  All about SQL Indexes - Query Optimizer, Index, Unique Index, Clustered Index, Full Text Index, XML Index and SQL commands to create, delete, and rename SQL indexes.

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• LAG function – practical use and comparison to old syntax

  - by Michael Zilberstein

  Recently I had to analyze huge trace – 46GB of trc files. Looping over files I loaded them into trace table using fn_trace_gettable function and filters I could use in order to filter out irrelevant data. I ended up with 6.5 million rows table, total of 7.4GB in size. It contained RowNum column which was defined as identity, primary key, clustered. One of the first things I detected was that although time difference between first and last events in the trace was 10 hours, total duration of all sql...(read more)

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• Exchange 2007 two node cluster setup on Windows 2008 Enterprise, install error

  - by Shadow00Caster

  I am installing Microsoft Exchange 2007 x64 in a two node environment using Microsoft Windows 2008 Enterprise x64. The Failover Cluster is all setup properly and following best practices for setting up the windows clustering for use with Exchange 2007. All the validation tests pass on the cluster and all of that portion is working fine. The problem is when I go to install the first Exchange node as an Active mailbox in configuration for a two node CCR. It gets all the way through the first 3 steps (Copy Exchange Files, Management Tools, Mailbox Role) and then fails on the 4th step 'Clustered Mailbox Server' with the following error: Error: The clustered mailbox server's group 'XXXX' was not found, and should already exist. Firewalls are all disabled, DNS is all setup properly, the environment has 3 domain controllers all 2k8 ent x64, all replication works. The name I pick for the CCR cluster (XXX) does not exist in AD or in DNS. I have attempted this install from both of the two Exchange nodes and multiple times .. tried with different names. I have been banging my head against the wall for days working on this and would appreciate any feedback on the issue.

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• Exchange 2010 DAG + VMWare HA = no support?

  - by Dan

  We currently have an Exchange 2003 clustered environment (two machine cluster) that we're looking to upgrade to 2010. We recently purchased a VMWare virtualization environment (three Dell R710's with an EMC NS-120 serving up NFS datastores - iSCSI is available) that we wish to use for this new environment. I'm seeing that Microsoft does not support Exchange 2010 DAGs with a virtualization high availability solution (see links below). I would like to utilize the DAG to ensure the data stays available if one host goes down, and HA to ensure that if the physical host goes down, the VM will come back up on the other available host. Does anybody know why MS does not support this? VMWare HA will only restart the VM if it is hung/down - I don't see any difference between this and restarting the physical box if someone pulled the power... Will we only run into issues with support if it has something to do with HA/DAG failover or will they see we have HA and tell us to put it on a physical box even if it has nothing to do with HA? If we disable HA for these VM's will that satisfy them on a support case? Has anybody set up an Exchange 2010 DAG on VMware with HA enabled? Will they have any issues with using an NFS datastore? We have much greater flexibility on the EMC with NFS vs iSCSI, so I would prefer to continue utilizing that. Thanks for any input! http://www.vmwareinfo.com/2010/01/verifying-microsoft-exchange-2010.html Take a look at the second image under "Not Supported" http://technet.microsoft.com/en-us/library/aa996719.aspx "Microsoft doesn't support combining Exchange high availability solutions (database availability groups (DAGs)) with hypervisor-based clustering, high availability, or migration solutions. DAGs are supported in hardware virtualization environments provided that the virtualization environment doesn't employ clustered root servers."

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• sql server uninstallation issue

  - by angel

  I'm unable to remove SQL Server 2008 sp1 completely from my system. I'm using windows 7 ultimate. Everytime I try uninstalling it i get the following error. How can I remove it? here is the log: Overall summary: Final result: Failed: see details below Exit code (Decimal): -2068643839 Exit facility code: 1203 Exit error code: 1 Exit message: Failed: see details below Start time: 2013-06-24 21:10:38 End time: 2013-06-24 21:21:17 Requested action: Uninstall Log with failure: C:\Program Files\Microsoft SQL Server\100\Setup Bootstrap\Log\20130624_210908\sql_rs_Cpu64_1.log Exception help link: http://go.microsoft.com/fwlink?LinkId=20476&ProdName=Microsoft+SQL+Server&EvtSrc=setup.rll&EvtID=50000&ProdVer=10.0.1600.22 Machine Properties: Machine name: ABHI-PC Machine processor count: 4 OS version: Windows Vista OS service pack: Service Pack 1 OS region: United States OS language: English (United States) OS architecture: x64 Process architecture: 64 Bit OS clustered: No Product features discovered: Product Instance Instance ID Feature Language Edition Version Clustered Sql Server 2008 MSSQLSERVER MSRS10.MSSQLSERVER Reporting Services 1033 Enterprise Edition 10.0.1600.22 No Sql Server 2008 Management Tools - Basic 10.0.1600.22 No Package properties: Description: SQL Server Database Services 2008 SQLProductFamilyCode: {628F8F38-600E-493D-9946-F4178F20A8A9} ProductName: SQL2008 Type: RTM Version: 10 SPLevel: 0 Installation edition: ENTERPRISE User Input Settings: ACTION: Uninstall CONFIGURATIONFILE: C:\Program Files\Microsoft SQL Server\100\Setup Bootstrap\Log\20130624_210908\ConfigurationFile.ini FEATURES: RS,SSMS,SNAC_SDK,CE_RUNTIME,CE_TOOLS,SNAC HELP: False INDICATEPROGRESS: False INSTANCEID: INSTANCENAME: MSSQLSERVER MEDIASOURCE: QUIET: False QUIETSIMPLE: False X86: False Configuration file: C:\Program Files\Microsoft SQL Server\100\Setup Bootstrap\Log\20130624_210908\ConfigurationFile.ini Detailed results: Feature: SQL Client Connectivity Status: Skipped MSI status: Passed Configuration status: Passed Feature: SQL Client Connectivity SDK Status: Skipped MSI status: Passed Configuration status: Passed Feature: Reporting Services Status: Failed: see logs for details MSI status: Passed Configuration status: Failed: see details below Configuration error code: 0xFFD65603 Configuration error description: Input string was not in a correct format. Configuration log: C:\Program Files\Microsoft SQL Server\100\Setup Bootstrap\Log\20130624_210908\Detail.txt Feature: SQL Compact Edition Tools Status: Passed MSI status: Passed Configuration status: Passed Feature: SQL Compact Edition Runtime Status: Skipped MSI status: Passed Configuration status: Passed Feature: Management Tools - Basic Status: Failed: see logs for details MSI status: Passed Configuration status: Passed Rules with failures: Global rules: There are no scenario-specific rules. Rules report file: C:\Program Files\Microsoft SQL Server\100\Setup Bootstrap\Log\20130624_210908\SystemConfigurationCheck_Report.htm

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• SQL SERVER – Update Statistics are Sampled By Default

  - by pinaldave

  After reading my earlier post SQL SERVER – Create Primary Key with Specific Name when Creating Table on Statistics, I have received another question by a blog reader. The question is as follows: Question: Are the statistics sampled by default? Answer: Yes. The sampling rate can be specified by the user and it can be anywhere between a very low value to 100%. Let us do a small experiment to verify if the auto update on statistics is left on. Also, let’s examine a very large table that is created and statistics by default- whether the statistics are sampled or not. USE [AdventureWorks] GO -- Create Table CREATE TABLE [dbo].[StatsTest]( [ID] [int] IDENTITY(1,1) NOT NULL, [FirstName] [varchar](100) NULL, [LastName] [varchar](100) NULL, [City] [varchar](100) NULL, CONSTRAINT [PK_StatsTest] PRIMARY KEY CLUSTERED ([ID] ASC) ) ON [PRIMARY] GO -- Insert 1 Million Rows INSERT INTO [dbo].[StatsTest] (FirstName,LastName,City) SELECT TOP 1000000 'Bob', CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%2 = 1 THEN 'Smith' ELSE 'Brown' END, CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 1 THEN 'New York' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 5 THEN 'San Marino' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 3 THEN 'Los Angeles' ELSE 'Houston' END FROM sys.all_objects a CROSS JOIN sys.all_objects b GO -- Update the statistics UPDATE STATISTICS [dbo].[StatsTest] GO -- Shows the statistics DBCC SHOW_STATISTICS ("StatsTest"PK_StatsTest) GO -- Clean up DROP TABLE [dbo].[StatsTest] GO Now let us observe the result of the DBCC SHOW_STATISTICS. The result shows that Resultset is for sure sampling for a large dataset. The percentage of sampling is based on data distribution as well as the kind of data in the table. Before dropping the table, let us check first the size of the table. The size of the table is 35 MB. Now, let us run the above code with lesser number of the rows. USE [AdventureWorks] GO -- Create Table CREATE TABLE [dbo].[StatsTest]( [ID] [int] IDENTITY(1,1) NOT NULL, [FirstName] [varchar](100) NULL, [LastName] [varchar](100) NULL, [City] [varchar](100) NULL, CONSTRAINT [PK_StatsTest] PRIMARY KEY CLUSTERED ([ID] ASC) ) ON [PRIMARY] GO -- Insert 1 Hundred Thousand Rows INSERT INTO [dbo].[StatsTest] (FirstName,LastName,City) SELECT TOP 100000 'Bob', CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%2 = 1 THEN 'Smith' ELSE 'Brown' END, CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 1 THEN 'New York' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 5 THEN 'San Marino' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 3 THEN 'Los Angeles' ELSE 'Houston' END FROM sys.all_objects a CROSS JOIN sys.all_objects b GO -- Update the statistics UPDATE STATISTICS [dbo].[StatsTest] GO -- Shows the statistics DBCC SHOW_STATISTICS ("StatsTest"PK_StatsTest) GO -- Clean up DROP TABLE [dbo].[StatsTest] GO You can see that Rows Sampled is just the same as Rows of the table. In this case, the sample rate is 100%. Before dropping the table, let us also check the size of the table. The size of the table is less than 4 MB. Let us compare the Result set just for a valid reference. Test 1: Total Rows: 1000000, Rows Sampled: 255420, Size of the Table: 35.516 MB Test 2: Total Rows: 100000, Rows Sampled: 100000, Size of the Table: 3.555 MB The reason behind the sample in the Test1 is that the data space is larger than 8 MB, and therefore it uses more than 1024 data pages. If the data space is smaller than 8 MB and uses less than 1024 data pages, then the sampling does not happen. Sampling aids in reducing excessive data scan; however, sometimes it reduces the accuracy of the data as well. Please note that this is just a sample test and there is no way it can be claimed as a benchmark test. The result can be dissimilar on different machines. There are lots of other information can be included when talking about this subject. I will write detail post covering all the subject very soon. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Index, SQL Optimization, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: SQL Statistics

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• AIX Grid Control 10.2.0.5 Communication and Monitoring Issue since 31-DEC-2010

  - by jayatheertha.rao(at)oracle.com

  Detailed symptoms for Oracle Management Server (OMS) 10.2.0.5 on AIX Oracle Management Service 10.2.0.5 instances on AIX 5L remain active and functional, but the OMS instances fail to communicate with the Grid Control Management Agents.An SSLPeerUnverified exception will be reported in the file $ORACLE_HOME/sysman/log/emoms.trc when OMS attempts to connect with an Agent:Javax.net.ssl.SSLPeerUnverifiedException: peer not authenticatedat com.sun.net.ssl.internal.ssl.SSLSessionImpl.getPeerCertificateChain(DashoA12275)at oracle.sysman.emSDK.emd.comm.EMDClient.authenticateHTTPConnection(EMDClient.java:2002)at oracle.sysman.emSDK.emd.comm.EMDClient.getConnection(EMDClient.java:1877)at oracle.sysman.emSDK.emd.comm.EMDClient.getConnection(EMDClient.java:1810)at oracle.sysman.emSDK.emd.comm.EMDClient.verifyHttpConnection(EMDClient.java:2540)at oracle.sysman.emSDK.emd.comm.EMDClient.getResponseForRequest(EMDClient.java:2323)at oracle.sysman.emSDK.emd.comm.EMDClient.getUploadManagerStatus(EMDClient.java:4853)at oracle.sysman.eml.admin.rep.emdConfig.EmdConfigTargetsData.getEmdUploadData(EmdConfigTargetsData.java:1640)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)This error may be reported when:- Accessing the Agent home page in Grid Control- Setting preferred credentials for a target monitored by the Agent- Managing metrics for a target monitored by the Agent The jobs scheduled to be run by Agents can become non-responsiveThe OMS log file $ORACLE_HOME/sysman/log/emoms.trc can show:2010-12-31 00:06:58,204 [JobWorker 430:Thread-34] DEBUG emSDK.comm getStreamResponse.4015 - oracle.sysman.emSDK.emd.comm.CommException: java.io.IOException: javax.net.ssl.SSLPeerUnverifiedException: peer not authenticatedoracle.sysman.emSDK.emd.comm.CommException: java.io.IOException: javax.net.ssl.SSLPeerUnverifiedException: peer not authenticatedat oracle.sysman.emSDK.emd.comm.EMDClient.getStreamResponse_(EMDClient.java:4088)at oracle.sysman.emSDK.emd.comm.EMDClient.getStreamResponse(EMDClient.java:4009)at oracle.sysman.emSDK.emd.comm.EMDClient.remoteOperation(EMDClient.java:3404)at oracle.sysman.emdrep.jobs.CommandManager.requestRemoteCommand(CommandManager.java:765)at oracle.sysman.emdrep.jobs.commands.RemoteOp.executeCommand(RemoteOp.java:434)at oracle.sysman.emdrep.jobs.commands.RemoteOp.executeCommand(RemoteOp.java:491)at oracle.sysman.emdrep.jobs.BaseJobWorker.runStep(BaseJobWorker.java:614)at oracle.sysman.emdrep.jobs.BaseJobWorker.doOneOperation(BaseJobWorker.java:738)at oracle.sysman.emdrep.jobs.JobWorker.doOneOperation(JobWorker.java:306)at oracle.sysman.emdrep.jobs.JobWorker.run(JobWorker.java:288)at oracle.sysman.util.threadPoolManager.WorkerThread.run(Worker.java:261) Detailed symptoms for Grid Control Management Agent 10.2.0.5 on AIX Beginning 31-DEC-2010 00:00:00, 10.2.0.5 Management Agents running on the AIX 5L operating system will fail to monitor Oracle Application Server targets. As a result, the Availability Status for the Oracle Application Server targets will be in the "Metric Error" state. NOTE: The 10.2.0.5.0 Agents would experience these errors regardless of the version/platform of the OMS.The following metric error is seen in the console for the Oracle Application Server targets monitored by a Grid Control Management Agent 10.2.0.5 installed on AIX and experiencing a Root Certificate Authority issue:Message oracle.sysman.emSDK.emd.fetchlet.FetchletException: oracle.sysman.emSDK.emd.fetchlet.FetchletException: oracle.sysman.emSDK.emd.fetchlet.FetchletException: oracle.sysman.emSDK.emd.comm.CommException: java.io.IOException: javax.net.ssl.SSLPeerUnverifiedException: peer not authenticated The Grid Control Management Agent log file $ORACLE_HOME/sysman/log/emagentfetchlet.log (or $ORACLE_HOME/hostname/sysman/log/emagentfetchlet.log for a clustered Agent) includes the following errors:2010-12-31 00:01:03,626 [nmefmgr_getJNIFetchlet] ERROR ias.ResponseMetric getResponseMetric.154 - Unable tocompute application server statusoracle.sysman.emSDK.emd.fetchlet.FetchletException: oracle.sysman.emSDK.emd.comm.CommException: java.io.IOException: javax.net.ssl.SSLPeerUnverifiedException: peer not authenticatedat oracle.sysman.ias.ias.ResponseMetric.getResponseMetric(ResponseMetric.java:108)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:79)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)at java.lang.reflect.Method.invoke(Method.java:618)at oracle.sysman.emd.fetchlets.JavaWrapperFetchlet.getMetric(JavaWrapperFetchlet.java:217)at oracle.sysman.emd.fetchlets.FetchletWrapper.getMetric(FetchletWrapper.java:382) Beginning 31-DEC-2010, 10.2.0.5 Management Agents on the AIX 5L platform will fail to secure or re-secure with Oracle Management Service (OMS). This failure will cause installation of 10.2.0.5 Agents on the AIX 5L platform to fail.NOTE: The 10.2.0.5.0 Agents would experience these errors regardless of the version/platform of the OMS.The "emctl secure agent" command will fail with the following error, which will be written to the $ORACLE_HOME/sysman/log/secure.log file (or $ORACLE_HOME/hostname/sysman/log/secure.log for a clustered Agent) :2011-01-03 21:06:11,941 [main] ERROR agent.SecureAgentCmd main.207 - Failedto secure the Agent:javax.net.ssl.SSLPeerUnverifiedException: peer not authenticatedatcom.sun.net.ssl.internal.ssl.SSLSessionImpl.getPeerCertificateChain(DashoA6275)atoracle.sysman.emctl.secure.agent.SecureAgentCmd.checkUpload(SecureAgentCmd.java:478)atoracle.sysman.emctl.secure.agent.SecureAgentCmd.secureAgent(SecureAgentCmd.java:249)atoracle.sysman.emctl.secure.agent.SecureAgentCmd.main(SecureAgentCmd.java:200)  For solution, refer to AIX Grid Control 10.2.0.5 SSL Communication and Monitoring Issue since 31-DEC-2010 (Doc ID 1275070.1)

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• SQL SERVER – Transcript of Learning SQL Server Performance: Indexing Basics – Interview of Vinod Kumar by Pinal Dave

  - by pinaldave

  Recently I just wrote a blog post on about Learning SQL Server Performance: Indexing Basics and I received lots of request that if we can share some insight into the course. Here is 200 seconds interview of Vinod Kumar I took right after completing the course. We have few free codes to watch the course, please your comment at http://facebook.com/SQLAuth and we will few of first ones, we will send the code. There are many people who said they would like to read the transcript of the video. Here I have generated the same. Pinal: Vinod, we recently released this course, SQL Server Indexing. It is about performance tuning. So tell me – how do indexes help performance? Vinod: I think what happens in the industry when it comes to performance is that developers and DBAs look at indexes first.  So that’s the first step for any performance tuning exercise, indexing is one of the most critical aspects and it is important to learn it the right way. Pinal: Correct. So what you mean to say is that if you know indexing you can pretty much tune any server and query. Vinod: So I might contradict my false statement now. Indexing is usually a stepping stone but it does not lead you to the end. But it’s good to start with indexing and there are lots of nuances to indexing that you need to understand, like how SQL uses indexing and how performance can improve because of the strategies that you have made. Pinal: But now I’m confused. First you said indexes are good, and then you said that indexes can degrade your performance.  So what is this course about?  I mean how does this course really make an impact? Vinod: Ok -so from the course perspective, what we are trying to do is give you a capsule which gives you a good start. Every journey needs a beginning, you need that first step.  This course is that first step in understanding. This is the most basic, fundamental course that we have tried to attack. This is the fundamentals of indexing, some of the key things that you must know about indexing.   Some of the basics of indexing are lesser known and so I think this course is geared towards each and every one of you out there who wants to understand little bit more about indexing. Pinal: So what I understand is that if I enrolled in this course I will have a minimum understanding about indexing when dealing with performance tuning.  Right? Vinod: Exactly. In this course is we have tried to give you a nice summary. We are talking about clustered indexing, non clustered indexing, too many indexes, too few indexes, over indexing, under indexing, duplicate indexing, columns tune indexing, with SQL Server 2012. There’s lot’s to learn. Pinal: You can see the URL [http://bit.ly/sql-index] of the course on the screen. Go ahead, attend, and let us know what you think about it. Thank you. Vinod: Thank you. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Index, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology, Video

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• SQL SERVER – Updating Data in A Columnstore Index

  - by pinaldave

  So far I have written two articles on Columnstore Indexes, and both of them got very interesting readership. In fact, just recently I got a query on my previous article on Columnstore Index. Read the following two articles to get familiar with the Columnstore Index. They will give you a reference to the question which was asked by a certain reader: SQL SERVER – Fundamentals of Columnstore Index SQL SERVER – How to Ignore Columnstore Index Usage in Query Here is the reader’s question: ” When I tried to update my table after creating the Columnstore index, it gives me an error. What should I do?” When the Columnstore index is created on the table, the table becomes Read-Only table and it does not let any insert/update/delete on the table. The basic understanding is that Columnstore Index will be created on the table that is very huge and holds lots of data. If a table is small enough, there is no need to create a Columnstore index. The regular index should just help it. The reason why Columnstore index was needed is because the table was so big that retrieving the data was taking a really, really long time. Now, updating such a huge table is always a challenge by itself. If the Columnstore Index is created on the table, and the table needs to be updated, you need to know that there are various ways to update it. The easiest way is to disable the Index and enable it. Consider the following code: USE AdventureWorks GO -- Create New Table CREATE TABLE [dbo].[MySalesOrderDetail]( [SalesOrderID] [int] NOT NULL, [SalesOrderDetailID] [int] NOT NULL, [CarrierTrackingNumber] [nvarchar](25) NULL, [OrderQty] [smallint] NOT NULL, [ProductID] [int] NOT NULL, [SpecialOfferID] [int] NOT NULL, [UnitPrice] [money] NOT NULL, [UnitPriceDiscount] [money] NOT NULL, [LineTotal] [numeric](38, 6) NOT NULL, [rowguid] [uniqueidentifier] NOT NULL, [ModifiedDate] [datetime] NOT NULL ) ON [PRIMARY] GO -- Create clustered index CREATE CLUSTERED INDEX [CL_MySalesOrderDetail] ON [dbo].[MySalesOrderDetail] ( [SalesOrderDetailID]) GO -- Create Sample Data Table -- WARNING: This Query may run upto 2-10 minutes based on your systems resources INSERT INTO [dbo].[MySalesOrderDetail] SELECT S1.* FROM Sales.SalesOrderDetail S1 GO 100 -- Create ColumnStore Index CREATE NONCLUSTERED COLUMNSTORE INDEX [IX_MySalesOrderDetail_ColumnStore] ON [MySalesOrderDetail] (UnitPrice, OrderQty, ProductID) GO -- Attempt to Update the table UPDATE [dbo].[MySalesOrderDetail] SET OrderQty = OrderQty +1 WHERE [SalesOrderID] = 43659 GO /* It will throw following error Msg 35330, Level 15, State 1, Line 2 UPDATE statement failed because data cannot be updated in a table with a columnstore index. Consider disabling the columnstore index before issuing the UPDATE statement, then rebuilding the columnstore index after UPDATE is complete. */ A similar error also shows up for Insert/Delete function. Here is the workaround. Disable the Columnstore Index and performance update, enable the Columnstore Index: -- Disable the Columnstore Index ALTER INDEX [IX_MySalesOrderDetail_ColumnStore] ON [dbo].[MySalesOrderDetail] DISABLE GO -- Attempt to Update the table UPDATE [dbo].[MySalesOrderDetail] SET OrderQty = OrderQty +1 WHERE [SalesOrderID] = 43659 GO -- Rebuild the Columnstore Index ALTER INDEX [IX_MySalesOrderDetail_ColumnStore] ON [dbo].[MySalesOrderDetail] REBUILD GO This time it will not throw an error while the update of the table goes successfully. Let us do a cleanup of our tables using this code: -- Cleanup DROP INDEX [IX_MySalesOrderDetail_ColumnStore] ON [dbo].[MySalesOrderDetail] GO TRUNCATE TABLE dbo.MySalesOrderDetail GO DROP TABLE dbo.MySalesOrderDetail GO In the next post we will see how we can use Partition to update the Columnstore Index. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Index, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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