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• Joins in single-table queries

  - by Rob Farley

  Tables are only metadata. They don’t store data. I’ve written something about this before, but I want to take a viewpoint of this idea around the topic of joins, especially since it’s the topic for T-SQL Tuesday this month. Hosted this time by Sebastian Meine (@sqlity), who has a whole series on joins this month. Good for him – it’s a great topic. In that last post I discussed the fact that we write queries against tables, but that the engine turns it into a plan against indexes. My point wasn’t simply that a table is actually just a Clustered Index (or heap, which I consider just a special type of index), but that data access always happens against indexes – never tables – and we should be thinking about the indexes (specifically the non-clustered ones) when we write our queries. I described the scenario of looking up phone numbers, and how it never really occurs to us that there is a master list of phone numbers, because we think in terms of the useful non-clustered indexes that the phone companies provide us, but anyway – that’s not the point of this post. So a table is metadata. It stores information about the names of columns and their data types. Nullability, default values, constraints, triggers – these are all things that define the table, but the data isn’t stored in the table. The data that a table describes is stored in a heap or clustered index, but it goes further than this. All the useful data is going to live in non-clustered indexes. Remember this. It’s important. Stop thinking about tables, and start thinking about indexes. So let’s think about tables as indexes. This applies even in a world created by someone else, who doesn’t have the best indexes in mind for you. I’m sure you don’t need me to explain Covering Index bit – the fact that if you don’t have sufficient columns “included” in your index, your query plan will either have to do a Lookup, or else it’ll give up using your index and use one that does have everything it needs (even if that means scanning it). If you haven’t seen that before, drop me a line and I’ll run through it with you. Or go and read a post I did a long while ago about the maths involved in that decision. So – what I’m going to tell you is that a Lookup is a join. When I run SELECT CustomerID FROM Sales.SalesOrderHeader WHERE SalesPersonID = 285; against the AdventureWorks2012 get the following plan: I’m sure you can see the join. Don’t look in the query, it’s not there. But you should be able to see the join in the plan. It’s an Inner Join, implemented by a Nested Loop. It’s pulling data in from the Index Seek, and joining that to the results of a Key Lookup. It clearly is – the QO wouldn’t call it that if it wasn’t really one. It behaves exactly like any other Nested Loop (Inner Join) operator, pulling rows from one side and putting a request in from the other. You wouldn’t have a problem accepting it as a join if the query were slightly different, such as SELECT sod.OrderQty FROM Sales.SalesOrderHeader AS soh JOIN Sales.SalesOrderDetail as sod on sod.SalesOrderID = soh.SalesOrderID WHERE soh.SalesPersonID = 285; Amazingly similar, of course. This one is an explicit join, the first example was just as much a join, even thought you didn’t actually ask for one. You need to consider this when you’re thinking about your queries. But it gets more interesting. Consider this query: SELECT SalesOrderID FROM Sales.SalesOrderHeader WHERE SalesPersonID = 276 AND CustomerID = 29522; It doesn’t look like there’s a join here either, but look at the plan. That’s not some Lookup in action – that’s a proper Merge Join. The Query Optimizer has worked out that it can get the data it needs by looking in two separate indexes and then doing a Merge Join on the data that it gets. Both indexes used are ordered by the column that’s indexed (one on SalesPersonID, one on CustomerID), and then by the CIX key SalesOrderID. Just like when you seek in the phone book to Farley, the Farleys you have are ordered by FirstName, these seek operations return the data ordered by the next field. This order is SalesOrderID, even though you didn’t explicitly put that column in the index definition. The result is two datasets that are ordered by SalesOrderID, making them very mergeable. Another example is the simple query SELECT CustomerID FROM Sales.SalesOrderHeader WHERE SalesPersonID = 276; This one prefers a Hash Match to a standard lookup even! This isn’t just ordinary index intersection, this is something else again! Just like before, we could imagine it better with two whole tables, but we shouldn’t try to distinguish between joining two tables and joining two indexes. The Query Optimizer can see (using basic maths) that it’s worth doing these particular operations using these two less-than-ideal indexes (because of course, the best indexese would be on both columns – a composite such as (SalesPersonID, CustomerID – and it would have the SalesOrderID column as part of it as the CIX key still). You need to think like this too. Not in terms of excusing single-column indexes like the ones in AdventureWorks2012, but in terms of having a picture about how you’d like your queries to run. If you start to think about what data you need, where it’s coming from, and how it’s going to be used, then you will almost certainly write better queries. …and yes, this would include when you’re dealing with regular joins across multiples, not just against joins within single table queries.

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• Installed Service Pack 3 for SQL Server 2005 but it does not show up when selecting @@version

  - by Blegger

  We installed Service Pack 3 for SQL Server 2005 Standard Edition (64-bit). In the Add or Remove Programs menu we have the following entries under Microsoft SQL Server 2005 (64-bit): Service Pack 3 for SQL Server Integration Services 64-bit) ENU (KB955706) Service Pack 3 for SQL Server Notification Services 2005 (64-bit) ENU (KB955706) Service Pack 3 for SQL Server Database Services 2005 (64-bit) ENU (KB955706) Service Pack 3 for SQL Server Tools and Workstation Components 2005 (64-bit) ENU (KB955706) But when I run the following query on the server: select @@version I get this result: Microsoft SQL Server 2005 - 9.00.4035.00 (X64) Nov 24 2008 16:17:31 Copyright (c) 1988-2005 Microsoft Corporation Standard Edition (64-bit) on Windows NT 5.2 (Build 3790: Service Pack 2) Why does it not display that it is running Service Pack 3?

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• BNF – how to read syntax?

  - by Piotr Rodak

  A few days ago I read post of Jen McCown (blog) about her idea of blogging about random articles from Books Online. I think this is a great idea, even if Jen says that it’s not exciting or sexy. I noticed that many of the questions that appear on forums and other media arise from pure fact that people asking questions didn’t bother to read and understand the manual – Books Online. Jen came up with a brilliant, concise acronym that describes very well the category of posts about Books Online – RTFM365. I take liberty of tagging this post with the same acronym. I often come across questions of type – ‘Hey, i am trying to create a table, but I am getting an error’. The error often says that the syntax is invalid. 1 CREATE TABLE dbo.Employees 2 (guid uniqueidentifier CONSTRAINT DEFAULT Guid_Default NEWSEQUENTIALID() ROWGUIDCOL, 3 Employee_Name varchar(60) 4 CONSTRAINT Guid_PK PRIMARY KEY (guid) ); 5 The answer is usually(1), ‘Ok, let me check it out.. Ah yes – you have to put name of the DEFAULT constraint before the type of constraint: 1 CREATE TABLE dbo.Employees 2 (guid uniqueidentifier CONSTRAINT Guid_Default DEFAULT NEWSEQUENTIALID() ROWGUIDCOL, 3 Employee_Name varchar(60) 4 CONSTRAINT Guid_PK PRIMARY KEY (guid) ); Why many people stumble on syntax errors? Is the syntax poorly documented? No, the issue is, that correct syntax of the CREATE TABLE statement is documented very well in Books Online and is.. intimidating. Many people can be taken aback by the rather complex block of code that describes all intricacies of the statement. However, I don’t know better way of defining syntax of the statement or command. The notation that is used to describe syntax in Books Online is a form of Backus-Naur notatiion, called BNF for short sometimes. This is a notation that was invented around 50 years ago, and some say that even earlier, around 400 BC – would you believe? Originally it was used to define syntax of, rather ancient now, ALGOL programming language (in 1950’s, not in ancient India). If you look closer at the definition of the BNF, it turns out that the principles of this syntax are pretty simple. Here are a few bullet points: italic_text is a placeholder for your identifier <italic_text_in_angle_brackets> is a definition which is described further. [everything in square brackets] is optional {everything in curly brackets} is obligatory everything | separated | by | operator is an alternative ::= “assigns” definition to an identifier Yes, it looks like these six simple points give you the key to understand even the most complicated syntax definitions in Books Online. Books Online contain an article about syntax conventions – have you ever read it? Let’s have a look at fragment of the CREATE TABLE statement: 1 CREATE TABLE 2 [ database_name . [ schema_name ] . | schema_name . ] table_name 3 ( { <column_definition> | <computed_column_definition> 4 | <column_set_definition> } 5 [ <table_constraint> ] [ ,...n ] ) 6 [ ON { partition_scheme_name ( partition_column_name ) | filegroup 7 | "default" } ] 8 [ { TEXTIMAGE_ON { filegroup | "default" } ] 9 [ FILESTREAM_ON { partition_scheme_name | filegroup 10 | "default" } ] 11 [ WITH ( <table_option> [ ,...n ] ) ] 12 [ ; ] Let’s look at line 2 of the above snippet: This line uses rules 3 and 5 from the list. So you know that you can create table which has specified one of the following. just name – table will be created in default user schema schema name and table name – table will be created in specified schema database name, schema name and table name – table will be created in specified database, in specified schema database name, .., table name – table will be created in specified database, in default schema of the user. Note that this single line of the notation describes each of the naming schemes in deterministic way. The ‘optionality’ of the schema_name element is nested within database_name.. section. You can use either database_name and optional schema name, or just schema name – this is specified by the pipe character ‘|’. The error that user gets with execution of the first script fragment in this post is as follows: Msg 156, Level 15, State 1, Line 2 Incorrect syntax near the keyword 'DEFAULT'. Ok, let’s have a look how to find out the correct syntax. Line number 3 of the BNF fragment above contains reference to <column_definition>. Since column_definition is in angle brackets, we know that this is a reference to notion described further in the code. And indeed, the very next fragment of BNF contains syntax of the column definition. 1 <column_definition> ::= 2 column_name <data_type> 3 [ FILESTREAM ] 4 [ COLLATE collation_name ] 5 [ NULL | NOT NULL ] 6 [ 7 [ CONSTRAINT constraint_name ] DEFAULT constant_expression ] 8 | [ IDENTITY [ ( seed ,increment ) ] [ NOT FOR REPLICATION ] 9 ] 10 [ ROWGUIDCOL ] [ <column_constraint> [ ...n ] ] 11 [ SPARSE ] Look at line 7 in the above fragment. It says, that the column can have a DEFAULT constraint which, if you want to name it, has to be prepended with [CONSTRAINT constraint_name] sequence. The name of the constraint is optional, but I strongly recommend you to make the effort of coming up with some meaningful name yourself. So the correct syntax of the CREATE TABLE statement from the beginning of the article is like this: 1 CREATE TABLE dbo.Employees 2 (guid uniqueidentifier CONSTRAINT Guid_Default DEFAULT NEWSEQUENTIALID() ROWGUIDCOL, 3 Employee_Name varchar(60) 4 CONSTRAINT Guid_PK PRIMARY KEY (guid) ); That is practically everything you should know about BNF. I encourage you to study the syntax definitions for various statements and commands in Books Online, you can find really interesting things hidden there. Technorati Tags: SQL Server,t-sql,BNF,syntax   (1) No, my answer usually is a question – ‘What error message? What does it say?’. You’d be surprised to know how many people think I can go through time and space and look at their screen at the moment they received the error.

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• Using SQL Execution Plans to discover the Swedish alphabet

  - by Rob Farley

  SQL Server is quite remarkable in a bunch of ways. In this post, I’m using the way that the Query Optimizer handles LIKE to keep it SARGable, the Execution Plans that result, Collations, and PowerShell to come up with the Swedish alphabet. SARGability is the ability to seek for items in an index according to a particular set of criteria. If you don’t have SARGability in play, you need to scan the whole index (or table if you don’t have an index). For example, I can find myself in the phonebook easily, because it’s sorted by LastName and I can find Farley in there by moving to the Fs, and so on. I can’t find everyone in my suburb easily, because the phonebook isn’t sorted that way. I can’t even find people who have six letters in their last name, because also the book is sorted by LastName, it’s not sorted by LEN(LastName). This is all stuff I’ve looked at before, including in the talk I gave at SQLBits in October 2010. If I try to find everyone who’s names start with F, I can do that using a query a bit like: SELECT LastName FROM dbo.PhoneBook WHERE LEFT(LastName,1) = 'F'; Unfortunately, the Query Optimizer doesn’t realise that all the entries that satisfy LEFT(LastName,1) = 'F' will be together, and it has to scan the whole table to find them. But if I write: SELECT LastName FROM dbo.PhoneBook WHERE LastName LIKE 'F%'; then SQL is smart enough to understand this, and performs an Index Seek instead. To see why, I look further into the plan, in particular, the properties of the Index Seek operator. The ToolTip shows me what I’m after: You’ll see that it does a Seek to find any entries that are at least F, but not yet G. There’s an extra Predicate in there (a Residual Predicate if you like), which checks that each LastName is really LIKE F% – I suppose it doesn’t consider that the Seek Predicate is quite enough – but most of the benefit is seen by its working out the Seek Predicate, filtering to just the “at least F but not yet G” section of the data. This got me curious though, particularly about where the G comes from, and whether I could leverage it to create the Swedish alphabet. I know that in the Swedish language, there are three extra letters that appear at the end of the alphabet. One of them is ä that appears in the word Västerås. It turns out that Västerås is quite hard to find in an index when you’re looking it up in a Swedish map. I talked about this briefly in my five-minute talk on Collation from SQLPASS (the one which was slightly less than serious). So by looking at the plan, I can work out what the next letter is in the alphabet of the collation used by the column. In other words, if my alphabet were Swedish, I’d be able to tell what the next letter after F is – just in case it’s not G. It turns out it is… Yes, the Swedish letter after F is G. But I worked this out by using a copy of my PhoneBook table that used the Finnish_Swedish_CI_AI collation. I couldn’t find how the Query Optimizer calculates the G, and my friend Paul White (@SQL_Kiwi) tells me that it’s frustratingly internal to the QO. He’s particularly smart, even if he is from New Zealand. To investigate further, I decided to do some PowerShell, leveraging the Get-SqlPlan function that I blogged about recently (make sure you also have the SqlServerCmdletSnapin100 snap-in added). I started by indicating that I was going to use Finnish_Swedish_CI_AI as my collation of choice, and that I’d start whichever letter cam straight after the number 9. I figure that this is a cheat’s way of guessing the first letter of the alphabet (but it doesn’t actually work in Unicode – luckily I’m using varchar not nvarchar. Actually, there are a few aspects of this code that only work using ASCII, so apologies if you were wanting to apply it to Greek, Japanese, etc). I also initialised my $alphabet variable. $collation = 'Finnish_Swedish_CI_AI'; $firstletter = '9'; $alphabet = ''; Now I created the table for my test. A single field would do, and putting a Clustered Index on it would suffice for the Seeks. Invoke-Sqlcmd -server . -data tempdb -query "create table dbo.collation_test (col varchar(10) collate $collation primary key);" Now I get into the looping. $c = $firstletter; $stillgoing = $true; while ($stillgoing) { I construct the query I want, seeking for entries which start with whatever $c has reached, and get the plan for it: $query = "select col from dbo.collation_test where col like '$($c)%';"; [xml] $pl = get-sqlplan $query "." "tempdb"; At this point, my $pl variable is a scary piece of XML, representing the execution plan. A bit of hunting through it showed me that the EndRange element contained what I was after, and that if it contained NULL, then I was done. $stillgoing = ($pl.ShowPlanXML.BatchSequence.Batch.Statements.StmtSimple.QueryPlan.RelOp.IndexScan.SeekPredicates.SeekPredicateNew.SeekKeys.EndRange -ne $null); Now I could grab the value out of it (which came with apostrophes that needed stripping), and append that to my $alphabet variable.   if ($stillgoing)   {  $c=$pl.ShowPlanXML.BatchSequence.Batch.Statements.StmtSimple.QueryPlan.RelOp.IndexScan.SeekPredicates.SeekPredicateNew.SeekKeys.EndRange.RangeExpressions.ScalarOperator.ScalarString.Replace("'","");     $alphabet += $c;   } Finally, finishing the loop, dropping the table, and showing my alphabet! } Invoke-Sqlcmd -server . -data tempdb -query "drop table dbo.collation_test;"; $alphabet; When I run all this, I see that the Swedish alphabet is ABCDEFGHIJKLMNOPQRSTUVXYZÅÄÖ, which matches what I see at Wikipedia. Interesting to see that the letters on the end are still there, even with Case Insensitivity. Turns out they’re not just “letters with accents”, they’re letters in their own right. I’m sure you gave up reading long ago, and really aren’t that fazed about the idea of doing this using PowerShell. I chose PowerShell because I’d already come up with an easy way of grabbing the estimated plan for a query, and PowerShell does allow for easy navigation of XML. I find the most interesting aspect of this as the fact that the Query Optimizer uses the next letter of the alphabet to maintain the SARGability of LIKE. I’m hoping they do something similar for a whole bunch of operations. Oh, and the fact that you know how to find stuff in the IKEA catalogue. Footnote: If you are interested in whether this works in other languages, you might want to consider the following screenshot, which shows that in principle, it should work with Japanese. It might be a bit harder to run this in PowerShell though, as I’m not sure how it translates. In Hiragana, the Japanese alphabet starts ?, ?, ?, ?, ?, ...

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• Fraud Detection with the SQL Server Suite Part 2

  - by Dejan Sarka

  This is the second part of the fraud detection whitepaper. You can find the first part in my previous blog post about this topic. My Approach to Data Mining Projects It is impossible to evaluate the time and money needed for a complete fraud detection infrastructure in advance. Personally, I do not know the customer’s data in advance. I don’t know whether there is already an existing infrastructure, like a data warehouse, in place, or whether we would need to build one from scratch. Therefore, I always suggest to start with a proof-of-concept (POC) project. A POC takes something between 5 and 10 working days, and involves personnel from the customer’s site – either employees or outsourced consultants. The team should include a subject matter expert (SME) and at least one information technology (IT) expert. The SME must be familiar with both the domain in question as well as the meaning of data at hand, while the IT expert should be familiar with the structure of data, how to access it, and have some programming (preferably Transact-SQL) knowledge. With more than one IT expert the most time consuming work, namely data preparation and overview, can be completed sooner. I assume that the relevant data is already extracted and available at the very beginning of the POC project. If a customer wants to have their people involved in the project directly and requests the transfer of knowledge, the project begins with training. I strongly advise this approach as it offers the establishment of a common background for all people involved, the understanding of how the algorithms work and the understanding of how the results should be interpreted, a way of becoming familiar with the SQL Server suite, and more. Once the data has been extracted, the customer’s SME (i.e. the analyst), and the IT expert assigned to the project will learn how to prepare the data in an efficient manner. Together with me, knowledge and expertise allow us to focus immediately on the most interesting attributes and identify any additional, calculated, ones soon after. By employing our programming knowledge, we can, for example, prepare tens of derived variables, detect outliers, identify the relationships between pairs of input variables, and more, in only two or three days, depending on the quantity and the quality of input data. I favor the customer’s decision of assigning additional personnel to the project. For example, I actually prefer to work with two teams simultaneously. I demonstrate and explain the subject matter by applying techniques directly on the data managed by each team, and then both teams continue to work on the data overview and data preparation under our supervision. I explain to the teams what kind of results we expect, the reasons why they are needed, and how to achieve them. Afterwards we review and explain the results, and continue with new instructions, until we resolve all known problems. Simultaneously with the data preparation the data overview is performed. The logic behind this task is the same – again I show to the teams involved the expected results, how to achieve them and what they mean. This is also done in multiple cycles as is the case with data preparation, because, quite frankly, both tasks are completely interleaved. A specific objective of the data overview is of principal importance – it is represented by a simple star schema and a simple OLAP cube that will first of all simplify data discovery and interpretation of the results, and will also prove useful in the following tasks. The presence of the customer’s SME is the key to resolving possible issues with the actual meaning of the data. We can always replace the IT part of the team with another database developer; however, we cannot conduct this kind of a project without the customer’s SME. After the data preparation and when the data overview is available, we begin the scientific part of the project. I assist the team in developing a variety of models, and in interpreting the results. The results are presented graphically, in an intuitive way. While it is possible to interpret the results on the fly, a much more appropriate alternative is possible if the initial training was also performed, because it allows the customer’s personnel to interpret the results by themselves, with only some guidance from me. The models are evaluated immediately by using several different techniques. One of the techniques includes evaluation over time, where we use an OLAP cube. After evaluating the models, we select the most appropriate model to be deployed for a production test; this allows the team to understand the deployment process. There are many possibilities of deploying data mining models into production; at the POC stage, we select the one that can be completed quickly. Typically, this means that we add the mining model as an additional dimension to an existing DW or OLAP cube, or to the OLAP cube developed during the data overview phase. Finally, we spend some time presenting the results of the POC project to the stakeholders and managers. Even from a POC, the customer will receive lots of benefits, all at the sole risk of spending money and time for a single 5 to 10 day project: The customer learns the basic patterns of frauds and fraud detection The customer learns how to do the entire cycle with their own people, only relying on me for the most complex problems The customer’s analysts learn how to perform much more in-depth analyses than they ever thought possible The customer’s IT experts learn how to perform data extraction and preparation much more efficiently than they did before All of the attendees of this training learn how to use their own creativity to implement further improvements of the process and procedures, even after the solution has been deployed to production The POC output for a smaller company or for a subsidiary of a larger company can actually be considered a finished, production-ready solution It is possible to utilize the results of the POC project at subsidiary level, as a finished POC project for the entire enterprise Typically, the project results in several important “side effects” Improved data quality Improved employee job satisfaction, as they are able to proactively contribute to the central knowledge about fraud patterns in the organization Because eventually more minds get to be involved in the enterprise, the company should expect more and better fraud detection patterns After the POC project is completed as described above, the actual project would not need months of engagement from my side. This is possible due to our preference to transfer the knowledge onto the customer’s employees: typically, the customer will use the results of the POC project for some time, and only engage me again to complete the project, or to ask for additional expertise if the complexity of the problem increases significantly. I usually expect to perform the following tasks: Establish the final infrastructure to measure the efficiency of the deployed models Deploy the models in additional scenarios Through reports By including Data Mining Extensions (DMX) queries in OLTP applications to support real-time early warnings Include data mining models as dimensions in OLAP cubes, if this was not done already during the POC project Create smart ETL applications that divert suspicious data for immediate or later inspection I would also offer to investigate how the outcome could be transferred automatically to the central system; for instance, if the POC project was performed in a subsidiary whereas a central system is available as well Of course, for the actual project, I would repeat the data and model preparation as needed It is virtually impossible to tell in advance how much time the deployment would take, before we decide together with customer what exactly the deployment process should cover. Without considering the deployment part, and with the POC project conducted as suggested above (including the transfer of knowledge), the actual project should still only take additional 5 to 10 days. The approximate timeline for the POC project is, as follows: 1-2 days of training 2-3 days for data preparation and data overview 2 days for creating and evaluating the models 1 day for initial preparation of the continuous learning infrastructure 1 day for presentation of the results and discussion of further actions Quite frequently I receive the following question: are we going to find the best possible model during the POC project, or during the actual project? My answer is always quite simple: I do not know. Maybe, if we would spend just one hour more for data preparation, or create just one more model, we could get better patterns and predictions. However, we simply must stop somewhere, and the best possible way to do this, according to my experience, is to restrict the time spent on the project in advance, after an agreement with the customer. You must also never forget that, because we build the complete learning infrastructure and transfer the knowledge, the customer will be capable of doing further investigations independently and improve the models and predictions over time without the need for a constant engagement with me.

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• Querying the SSIS Catalog? Here’s a handy query!

  - by jamiet

  I’ve been working on a SQL Server Integration Services (SSIS) solution for about 6 months now and I’ve learnt many many things that I intend to share on this blog just as soon as I get the time. Here’s a very short starter-for-ten… I’ve found the following query to be utterly invaluable when interrogating the SSIS Catalog to discover what is going on in my executions: SELECT event_message_id,MESSAGE,package_name,event_name,message_source_name,package_path,execution_path,message_type,message_source_typeFROM   (       SELECT  em.*       FROM    SSISDB.catalog.event_messages em       WHERE   em.operation_id = (SELECT MAX(execution_id) FROM SSISDB.catalog.executions)           AND event_name NOT LIKE '%Validate%'       )q/* Put in whatever WHERE predicates you might like*/--WHERE event_name = 'OnError'--WHERE package_name = 'Package.dtsx'--WHERE execution_path LIKE '%<some executable>%'ORDER BY message_time DESC Know it. Learn it. Love it. @jamiet

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• Using transactions with LINQ-to-SQL

  - by Jalpesh P. Vadgama

  Today one of my colleague asked that how we can use transactions with the LINQ-to-SQL Classes when we use more then one entities updated at same time. It was a good question. Here is my answer for that.For ASP.NET 2.0  or higher version have a new class called TransactionScope which can be used to manage transaction with the LINQ. Let’s take a simple scenario we are having a shopping cart application in which we are storing details or particular order placed into the database using LINQ-to-SQL. There are two tables Order and OrderDetails which will have all the information related to order. Order will store particular information about orders while OrderDetails table will have product and quantity of product for particular order.We need to insert data in both tables as same time and if any errors comes then it should rollback the transaction. To use TransactionScope in above scenario first we have add a reference to System.Transactions like below. After adding the transaction we need to drag and drop the Order and Order Details tables into Linq-To-SQL Classes it will create entities for that. Below is the code for transaction scope to use mange transaction with Linq Context. MyContextDataContext objContext = new MyContextDataContext(); using (System.Transactions.TransactionScope tScope = new System.Transactions.TransactionScope(TransactionScopeOption.Required)) { objContext.Order.InsertOnSubmit(Order); objContext.OrderDetails.InsertOnSumbit(OrderDetails); objContext.SubmitChanges(); tScope.Complete(); } Here it will commit transaction only if using blocks will run successfully. Hope this will help you. Technorati Tags: Linq,Transaction,System.Transactions,ASP.NET

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• T-SQL Tuesday #33: Trick Shots: Undocumented, Underdocumented, and Unknown Conspiracies!

  - by Most Valuable Yak (Rob Volk)

  Mike Fal (b | t) is hosting this month's T-SQL Tuesday on Trick Shots.  I love this choice because I've been preoccupied with sneaky/tricky/evil SQL Server stuff for a long time and have been presenting on it for the past year.  Mike's directives were "Show us a cool trick or process you developed…It doesn’t have to be useful", which most of my blogging definitely fits, and "Tell us what you learned from this trick…tell us how it gave you insight in to how SQL Server works", which is definitely a new concept.  I've done a lot of reading and watching on SQL Server Internals and even attended training, but sometimes I need to go explore on my own, using my own tools and techniques.  It's an itch I get every few months, and, well, it sure beats workin'. I've found some people to be intimidated by SQL Server's internals, and I'll admit there are A LOT of internals to keep track of, but there are tons of excellent resources that clearly document most of them, and show how knowing even the basics of internals can dramatically improve your database's performance.  It may seem like rocket science, or even brain surgery, but you don't have to be a genius to understand it. Although being an "evil genius" can help you learn some things they haven't told you about. ;) This blog post isn't a traditional "deep dive" into internals, it's more of an approach to find out how a program works.  It utilizes an extremely handy tool from an even more extremely handy suite of tools, Sysinternals.  I'm not the only one who finds Sysinternals useful for SQL Server: Argenis Fernandez (b | t), Microsoft employee and former T-SQL Tuesday host, has an excellent presentation on how to troubleshoot SQL Server using Sysinternals, and I highly recommend it.  Argenis didn't cover the Strings.exe utility, but I'll be using it to "hack" the SQL Server executable (DLL and EXE) files. Please note that I'm not promoting software piracy or applying these techniques to attack SQL Server via internal knowledge. This is strictly educational and doesn't reveal any proprietary Microsoft information.  And since Argenis works for Microsoft and demonstrated Sysinternals with SQL Server, I'll just let him take the blame for it. :P (The truth is I've used Strings.exe on SQL Server before I ever met Argenis.) Once you download and install Strings.exe you can run it from the command line.  For our purposes we'll want to run this in the Binn folder of your SQL Server instance (I'm referencing SQL Server 2012 RTM): cd "C:\Program Files\Microsoft SQL Server\MSSQL11\MSSQL\Binn" C:\Program Files\Microsoft SQL Server\MSSQL11\MSSQL\Binn> strings *sql*.dll > sqldll.txt C:\Program Files\Microsoft SQL Server\MSSQL11\MSSQL\Binn> strings *sql*.exe > sqlexe.txt   I've limited myself to DLLs and EXEs that have "sql" in their names.  There are quite a few more but I haven't examined them in any detail. (Homework assignment for you!) If you run this yourself you'll get 2 text files, one with all the extracted strings from every SQL DLL file, and the other with the SQL EXE strings.  You can open these in Notepad, but you're better off using Notepad++, EditPad, Emacs, Vim or another more powerful text editor, as these will be several megabytes in size. And when you do open it…you'll find…a TON of gibberish.  (If you think that's bad, just try opening the raw DLL or EXE file in Notepad.  And by the way, don't do this in production, or even on a running instance of SQL Server.)  Even if you don't clean up the file, you can still use your editor's search function to find a keyword like "SELECT" or some other item you expect to be there.  As dumb as this sounds, I sometimes spend my lunch break just scanning the raw text for anything interesting.  I'm boring like that. Sometimes though, having these files available can lead to some incredible learning experiences.  For me the most recent time was after reading Joe Sack's post on non-parallel plan reasons.  He mentions a new SQL Server 2012 execution plan element called NonParallelPlanReason, and demonstrates a query that generates "MaxDOPSetToOne".  Joe (formerly on the Microsoft SQL Server product team, so he knows this stuff) mentioned that this new element was not currently documented and tried a few more examples to see what other reasons could be generated. Since I'd already run Strings.exe on the SQL Server DLLs and EXE files, it was easy to run grep/find/findstr for MaxDOPSetToOne on those extracts.  Once I found which files it belonged to (sqlmin.dll) I opened the text to see if the other reasons were listed.  As you can see in my comment on Joe's blog, there were about 20 additional non-parallel reasons.  And while it's not "documentation" of this underdocumented feature, the names are pretty self-explanatory about what can prevent parallel processing. I especially like the ones about cursors – more ammo! - and am curious about the PDW compilation and Cloud DB replication reasons. One reason completely stumped me: NoParallelHekatonPlan.  What the heck is a hekaton?  Google and Wikipedia were vague, and the top results were not in English.  I found one reference to Greek, stating "hekaton" can be translated as "hundredfold"; with a little more Wikipedia-ing this leads to hecto, the prefix for "one hundred" as a unit of measure.  I'm not sure why Microsoft chose hekaton for such a plan name, but having already learned some Greek I figured I might as well dig some more in the DLL text for hekaton.  Here's what I found: hekaton_slow_param_passing Occurs when a Hekaton procedure call dispatch goes to slow parameter passing code path The reason why Hekaton parameter passing code took the slow code path hekaton_slow_param_pass_reason sp_deploy_hekaton_database sp_undeploy_hekaton_database sp_drop_hekaton_database sp_checkpoint_hekaton_database sp_restore_hekaton_database e:\sql11_main_t\sql\ntdbms\hekaton\sqlhost\sqllang\hkproc.cpp e:\sql11_main_t\sql\ntdbms\hekaton\sqlhost\sqllang\matgen.cpp e:\sql11_main_t\sql\ntdbms\hekaton\sqlhost\sqllang\matquery.cpp e:\sql11_main_t\sql\ntdbms\hekaton\sqlhost\sqllang\sqlmeta.cpp e:\sql11_main_t\sql\ntdbms\hekaton\sqlhost\sqllang\resultset.cpp Interesting!  The first 4 entries (in red) mention parameters and "slow code".  Could this be the foundation of the mythical DBCC RUNFASTER command?  Have I been passing my parameters the slow way all this time? And what about those sp_xxxx_hekaton_database procedures (in blue)? Could THEY be the secret to a faster SQL Server? Could they promise a "hundredfold" improvement in performance?  Are these special, super-undocumented DIB (databases in black)? I decided to look in the SQL Server system views for any objects with hekaton in the name, or references to them, in hopes of discovering some new code that would answer all my questions: SELECT name FROM sys.all_objects WHERE name LIKE '%hekaton%' SELECT name FROM sys.all_objects WHERE object_definition(OBJECT_ID) LIKE '%hekaton%' Which revealed: name ------------------------ (0 row(s) affected) name ------------------------ sp_createstats sp_recompile sp_updatestats (3 row(s) affected)   Hmm.  Well that didn't find much.  Looks like these procedures are seriously undocumented, unknown, perhaps forbidden knowledge. Maybe a part of some unspeakable evil? (No, I'm not paranoid, I just like mysteries and thought that punching this up with that kind of thing might keep you reading.  I know I'd fall asleep without it.) OK, so let's check out those 3 procedures and see what they reveal when I search for "Hekaton": sp_createstats: -- filter out local temp tables, Hekaton tables, and tables for which current user has no permissions -- Note that OBJECTPROPERTY returns NULL on type="IT" tables, thus we only call it on type='U' tables   OK, that's interesting, let's go looking down a little further: ((@table_type<>'U') or (0 = OBJECTPROPERTY(@table_id, 'TableIsInMemory'))) and -- Hekaton table   Wellllll, that tells us a few new things: There's such a thing as Hekaton tables (UPDATE: I'm not the only one to have found them!) They are not standard user tables and probably not in memory UPDATE: I misinterpreted this because I didn't read all the code when I wrote this blog post. The OBJECTPROPERTY function has an undocumented TableIsInMemory option Let's check out sp_recompile: -- (3) Must not be a Hekaton procedure.   And once again go a little further: if (ObjectProperty(@objid, 'IsExecuted') <> 0 AND ObjectProperty(@objid, 'IsInlineFunction') = 0 AND ObjectProperty(@objid, 'IsView') = 0 AND -- Hekaton procedure cannot be recompiled -- Make them go through schema version bumping branch, which will fail ObjectProperty(@objid, 'ExecIsCompiledProc') = 0)   And now we learn that hekaton procedures also exist, they can't be recompiled, there's a "schema version bumping branch" somewhere, and OBJECTPROPERTY has another undocumented option, ExecIsCompiledProc.  (If you experiment with this you'll find this option returns null, I think it only works when called from a system object.) This is neat! Sadly sp_updatestats doesn't reveal anything new, the comments about hekaton are the same as sp_createstats.  But we've ALSO discovered undocumented features for the OBJECTPROPERTY function, which we can now search for: SELECT name, object_definition(OBJECT_ID) FROM sys.all_objects WHERE object_definition(OBJECT_ID) LIKE '%OBJECTPROPERTY(%'   I'll leave that to you as more homework.  I should add that searching the system procedures was recommended long ago by the late, great Ken Henderson, in his Guru's Guide books, as a great way to find undocumented features.  That seems to be really good advice! Now if you're a programmer/hacker, you've probably been drooling over the last 5 entries for hekaton (in green), because these are the names of source code files for SQL Server!  Does this mean we can access the source code for SQL Server?  As The Oracle suggested to Neo, can we return to The Source??? Actually, no. Well, maybe a little bit.  While you won't get the actual source code from the compiled DLL and EXE files, you'll get references to source files, debugging symbols, variables and module names, error messages, and even the startup flags for SQL Server.  And if you search for "DBCC" or "CHECKDB" you'll find a really nice section listing all the DBCC commands, including the undocumented ones.  Granted those are pretty easy to find online, but you may be surprised what those web sites DIDN'T tell you! (And neither will I, go look for yourself!)  And as we saw earlier, you'll also find execution plan elements, query processing rules, and who knows what else.  It's also instructive to see how Microsoft organizes their source directories, how various components (storage engine, query processor, Full Text, AlwaysOn/HADR) are split into smaller modules. There are over 2000 source file references, go do some exploring! So what did we learn?  We can pull strings out of executable files, search them for known items, browse them for unknown items, and use the results to examine internal code to learn even more things about SQL Server.  We've even learned how to use command-line utilities!  We are now 1337 h4X0rz!  (Not really.  I hate that leetspeak crap.) Although, I must confess I might've gone too far with the "conspiracy" part of this post.  I apologize for that, it's just my overactive imagination.  There's really no hidden agenda or conspiracy regarding SQL Server internals.  It's not The Matrix.  It's not like you'd find anything like that in there: Attach Matrix Database DM_MATRIX_COMM_PIPELINES MATRIXXACTPARTICIPANTS dm_matrix_agents   Alright, enough of this paranoid ranting!  Microsoft are not really evil!  It's not like they're The Borg from Star Trek: ALTER FEDERATION DROP ALTER FEDERATION SPLIT DROP FEDERATION   #tsql2sday

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• Compare those hard-to-reach servers with SQL Snapper

  - by Michelle Taylor

  If you’ve got an environment which is at the end of an unreliable or slow network connection, or isn’t connected to your network at all, and you want to do a deployment to that environment – then pointing SQL Compare at it directly is difficult or impossible. While you could run SQL Compare locally on that environment, if it’s a server – especially if it’s a locked-down server – you probably don’t want to go through the hassle of using another activation on it. Or possibly you’re not allowed to install software at all, because you don’t have admin rights – but you can run user-mode software. SQL Snapper is a standalone, licensing-free program which takes SQL Compare snapshots of a database. It can create a snapshot within the context of that environment which can then be moved to your working environment to run SQL Compare against, allowing you to create a deployment script for environments you can’t get SQL Compare into. Where can I find it? You can find RedGate.SQLSnapper.exe in your SQL Compare installation directory – if you haven’t changed it, that will be something like C:\Program Files (x86)\Red Gate\SQL Compare 10 (or 11 if you’re using our SQL Server 2014 support beta). As well as copying the executable, you’ll also currently need to copy the System.Threading.dll and RedGate.SOCCompareInterface.dll files from the same directory alongside it. How do I use it? SQL Snapper’s UI is just a cut-down version of the snapshot creation UI in SQL Compare – just fill in the boxes and create your snapshot, then bring it back to the place you use SQL Compare to compare against your difficult-to-reach environment. SQL Snapper also has a command-line mode if you can’t run the UI in your target environment – just specify the server, database and output location with the /server, /database and /mksnap arguments, and optionally the username and password if you’re using SQL security, e.g.: RedGate.SQLSnapper.exe /database:yourdatabase /server:yourservername /username:youruser /password:yourpassword /mksnap:filename.snp What’s the catch? There are a few limitations of SQL Snapper in its current form – notably, it can’t read encrypted objects, and you’ll also currently need to copy the System.Threading.dll and RedGate.SOCCompareInterface.dll files alongside it, which we recognise is a little awkward in some environments. If you use SQL Snapper and want to share your experiences, or help us work on improving the experience in future, please comment here or leave a request on the SQL Compare UserVoice at https://redgate.uservoice.com/forums/141379-sql-compare.

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• SQL Server 2005 to 2008 upgrade - are MDF files binary compatible?

  - by james

  I have 50 databases on a MS SQL Server 2005 system and want to upgrade to MS SQL Server 2008. This is what I tried on some test machines: 1. copied the \DATA directory from the source (MSSQL 2005) to exactly the same path on the target (MSSQL 2008) server. 2. edited the startup parameters on the MSSQL 2008 service to point to the path of the MSSQL 2005 master database. 3. restarted MSSQL service It worked and I can access all databases, tables and data. My questions are: I go back to SQL Server 4.2 and it has never been this easy. I know it worked, but should have it worked? Am I missing something, or is there going to be a gotcha next week? These are simple databases, with just tables, views and indexes. No cross database links, no triggers etc

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• Investigation: Can different combinations of components effect Dataflow performance?

  - by jamiet

  Introduction The Dataflow task is one of the core components (if not the core component) of SQL Server Integration Services (SSIS) and often the most misunderstood. This is not surprising, its an incredibly complicated beast and we’re abstracted away from that complexity via some boxes that go yellow red or green and that have some lines drawn between them. Example dataflow In this blog post I intend to look under that facade and get into some of the nuts and bolts of the Dataflow Task by investigating how the decisions we make when building our packages can affect performance. I will do this by comparing the performance of three dataflows that all have the same input, all produce the same output, but which all operate slightly differently by way of having different transformation components. I also want to use this blog post to challenge a common held opinion that I see perpetuated over and over again on the SSIS forum. That is, that people assume adding components to a dataflow will be detrimental to overall performance. Its not surprising that people think this –it is intuitive to think that more components means more work- however this is not a view that I share. I have always been of the opinion that there are many factors affecting dataflow duration and the number of components is actually one of the less important ones; having said that I have never proven that assertion and that is one reason for this investigation. I have actually seen evidence that some people think dataflow duration is simply a function of number of rows and number of components. I’ll happily call that one out as a myth even without any investigation!  The Setup I have a 2GB datafile which is a list of 4731904 (~4.7million) customer records with various attributes against them and it contains 2 columns that I am going to use for categorisation: [YearlyIncome] [BirthDate] The data file is a SSIS raw format file which I chose to use because it is the quickest way of getting data into a dataflow and given that I am testing the transformations, not the source or destination adapters, I want to minimise external influences as much as possible. In the test I will split the customers according to month of birth (12 of those) and whether or not their yearly income is above or below 50000 (2 of those); in other words I will be splitting them into 24 discrete categories and in order to do it I shall be using different combinations of SSIS’ Conditional Split and Derived Column transformation components. The 24 datapaths that occur will each input to a rowcount component, again because this is the least resource intensive means of terminating a datapath. The test is being carried out on a Dell XPS Studio laptop with a quad core (8 logical Procs) Intel Core i7 at 1.73GHz and Samsung SSD hard drive. Its running SQL Server 2008 R2 on Windows 7. The Variables Here are the three combinations of components that I am going to test:     One Conditional Split - A single Conditional Split component CSPL Split by Month of Birth and income category that will use expressions on [YearlyIncome] & [BirthDate] to send each row to one of 24 outputs. This next screenshot displays the expression logic in use: Derived Column & Conditional Split - A Derived Column component DER Income Category that adds a new column [IncomeCategory] which will contain one of two possible text values {“LessThan50000”,”GreaterThan50000”} and uses [YearlyIncome] to determine which value each row should get. A Conditional Split component CSPL Split by Month of Birth and Income Category then uses that new column in conjunction with [BirthDate] to determine which of the same 24 outputs to send each row to. Put more simply, I am separating the Conditional Split of #1 into a Derived Column and a Conditional Split. The next screenshots display the expression logic in use: DER Income Category         CSPL Split by Month of Birth and Income Category       Three Conditional Splits - A Conditional Split component that produces two outputs based on [YearlyIncome], one for each Income Category. Each of those outputs will go to a further Conditional Split that splits the input into 12 outputs, one for each month of birth (identical logic in each). In this case then I am separating the single Conditional Split of #1 into three Conditional Split components. The next screenshots display the expression logic in use: CSPL Split by Income Category         CSPL Split by Month of Birth 1& 2       Each of these combinations will provide an input to one of the 24 rowcount components, just the same as before. For illustration here is a screenshot of the dataflow containing three Conditional Split components: As you can these dataflows have a fair bit of work to do and remember that they’re doing that work for 4.7million rows. I will execute each dataflow 10 times and use the average for comparison. I foresee three possible outcomes: The dataflow containing just one Conditional Split (i.e. #1) will be quicker There is no significant difference between any of them One of the two dataflows containing multiple transformation components will be quicker Regardless of which of those outcomes come to pass we will have learnt something and that makes this an interesting test to carry out. Note that I will be executing the dataflows using dtexec.exe rather than hitting F5 within BIDS. The Results and Analysis The table below shows all of the executions, 10 for each dataflow. It also shows the average for each along with a standard deviation. All durations are in seconds. I’m pasting a screenshot because I frankly can’t be bothered with the faffing about needed to make a presentable HTML table. It is plain to see from the average that the dataflow containing three conditional splits is significantly faster, the other two taking 43% and 52% longer respectively. This seems strange though, right? Why does the dataflow containing the most components outperform the other two by such a big margin? The answer is actually quite logical when you put some thought into it and I’ll explain that below. Before progressing, a side note. The standard deviation for the “Three Conditional Splits” dataflow is orders of magnitude smaller – indicating that performance for this dataflow can be predicted with much greater confidence too. The Explanation I refer you to the screenshot above that shows how CSPL Split by Month of Birth and salary category in the first dataflow is setup. Observe that there is a case for each combination of Month Of Date and Income Category – 24 in total. These expressions get evaluated in the order that they appear and hence if we assume that Month of Date and Income Category are uniformly distributed in the dataset we can deduce that the expected number of expression evaluations for each row is 12.5 i.e. 1 (the minimum) + 24 (the maximum) divided by 2 = 12.5. Now take a look at the screenshots for the second dataflow. We are doing one expression evaluation in DER Income Category and we have the same 24 cases in CSPL Split by Month of Birth and Income Category as we had before, only the expression differs slightly. In this case then we have 1 + 12.5 = 13.5 expected evaluations for each row – that would account for the slightly longer average execution time for this dataflow. Now onto the third dataflow, the quick one. CSPL Split by Income Category does a maximum of 2 expression evaluations thus the expected number of evaluations per row is 1.5. CSPL Split by Month of Birth 1 & CSPL Split by Month of Birth 2 both have less work to do than the previous Conditional Split components because they only have 12 cases to test for thus the expected number of expression evaluations is 6.5 There are two of them so total expected number of expression evaluations for this dataflow is 6.5 + 6.5 + 1.5 = 14.5. 14.5 is still more than 12.5 & 13.5 though so why is the third dataflow so much quicker? Simple, the conditional expressions in the first two dataflows have two boolean predicates to evaluate – one for Income Category and one for Month of Birth; the expressions in the Conditional Split in the third dataflow however only have one predicate thus they are doing a lot less work. To sum up, the difference in execution times can be attributed to the difference between: MONTH(BirthDate) == 1 && YearlyIncome <= 50000 and MONTH(BirthDate) == 1 In the first two dataflows YearlyIncome <= 50000 gets evaluated an average of 12.5 times for every row whereas in the third dataflow it is evaluated once and once only. Multiply those 11.5 extra operations by 4.7million rows and you get a significant amount of extra CPU cycles – that’s where our duration difference comes from. The Wrap-up The obvious point here is that adding new components to a dataflow isn’t necessarily going to make it go any slower, moreover you may be able to achieve significant improvements by splitting logic over multiple components rather than one. Performance tuning is all about reducing the amount of work that needs to be done and that doesn’t necessarily mean use less components, indeed sometimes you may be able to reduce workload in ways that aren’t immediately obvious as I think I have proven here. Of course there are many variables in play here and your mileage will most definitely vary. I encourage you to download the package and see if you get similar results – let me know in the comments. The package contains all three dataflows plus a fourth dataflow that will create the 2GB raw file for you (you will also need the [AdventureWorksDW2008] sample database from which to source the data); simply disable all dataflows except the one you want to test before executing the package and remember, execute using dtexec, not within BIDS. If you want to explore dataflow performance tuning in more detail then here are some links you might want to check out: Inequality joins, Asynchronous transformations and Lookups Destination Adapter Comparison Don’t turn the dataflow into a cursor SSIS Dataflow – Designing for performance (webinar) Any comments? Let me know! @Jamiet

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• Have SSIS' differing type systems ever caused you problems?

  - by jamiet

  One thing that has always infuriated me about SSIS is the fact that every package has three different type systems; to give you an idea of what I am talking about consider the following: The SSIS dataflow's type system is made up of types called DT_*  (e.g. DT_STR, DT_I4) The SSIS variable type system is based on .Net datatypes (e.g. String, Int32) The types available for Execute SQL Task's parameters are based on something else - I don't exactly know what (e.g. VARCHAR, LONG) Speaking euphemistically ... this is not an optimum situation (were I not speaking euphemistically I would be a lot ruder) and hence I have submitted a suggestion to Connect at [SSIS] Consolidate three type systems into one requesting that it be remedied. This accompanying blog post is not however a request for votes (though that would be nice); the reason is actually subtler than that. Let me explain. I have been submitting bugs and suggestions pertaining to SSIS for years and have, so far, submitted over 200 Connect items. If that experience has taught me anything it is this - Connect items are not generally actioned because they are considered "nice to have". No, SSIS Connect items get actioned because they cause customers grief and if I am perfectly honest I must admit that, other than being a bit gnarly, SSIS' three type system architecture has never knowingly caused me any significant problems. The reason for this blog post is to ask if any reader out there has ever encountered any problems on account of SSIS' three type systems or have you, like me, never found them to be a problem? Errors or performance degredation caused by implicit type conversions would, I believe, present a strong case for getting this situation remedied in a future version of SSIS so if you HAVE encountered such problems I would encourage you to leave a comment on the Connect submission accordingly. Let me know in the comments too - I would be interested to hear others' opinions on this. @Jamiet

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• Performance-Driven Development

  - by BuckWoody

  I was reading a blog yesterday about the evils of SELECT *. The author pointed out that it's almost always a bad idea to use SELECT * for a query, but in the case of SQL Azure (or any cloud database, for that matter) it's especially bad, since you're paying for each transmission that comes down the line. A very good point indeed. This got me to thinking - shouldn't we treat ALL programming that way? In other words, wouldn't it make sense to pretend that we are paying for every chunk of data - a little less for a bit, a lot more for a BLOB or VARCHAR(MAX), that sort of thing? In effect, we really are paying for that. Which led me to the thought of Performance-Driven Development, or the act of programming with the goal of having the fastest code from the very outset. This isn't an original title, since a quick Bing-search shows me a couple of offerings from Forrester and a professional in Israel who already used that title, but the general idea I'm thinking of is assigning a "cost" to each code round-trip, be it network, storage, trip time and other variables, and then rewarding the developers that come up with the fastest code. I wonder what kind of throughput and round-trip times you could get if your developers were paid on a scale of how fast the application performed... Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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• Change Data Capture

  - by Ricardo Peres

  There's an hidden gem in SQL Server 2008: Change Data Capture (CDC). Using CDC we get full audit capabilities with absolutely no implementation code: we can see all changes made to a specific table, including the old and new values! You can only use CDC in SQL Server 2008 Standard or Enterprise, Express edition is not supported. Here are the steps you need to take, just remember SQL Agent must be running: use SomeDatabase; -- first create a table CREATE TABLE Author ( ID INT NOT NULL PRIMARY KEY IDENTITY(1, 1), Name NVARCHAR(20) NOT NULL, EMail NVARCHAR(50) NOT NULL, Birthday DATE NOT NULL ) -- enable CDC at the DB level EXEC sys.sp_cdc_enable_db -- check CDC is enabled for the current DB SELECT name, is_cdc_enabled FROM sys.databases WHERE name = 'SomeDatabase' -- enable CDC for table Author, all columns exec sys.sp_cdc_enable_table @source_schema = 'dbo', @source_name = 'Author', @role_name = null -- insert values into table Author insert into Author (Name, EMail, Birthday, Username) values ('Bla', 'bla@bla', 1990-10-10, 'bla') -- check CDC data for table Author -- __$operation: 1 = DELETE, 2 = INSERT, 3 = BEFORE UPDATE 4 = AFTER UPDATE -- __$start_lsn: operation timestamp select * from cdc.dbo_author_CT -- update table Author update Author set EMail = '[email protected]' where Name = 'Bla' -- check CDC data for table Author select * from cdc.dbo_author_CT -- delete from table Author delete from Author -- check CDC data for table Author select * from cdc.dbo_author_CT -- disable CDC for table Author -- this removes all CDC data, so be carefull exec sys.sp_cdc_disable_table @source_schema = 'dbo', @source_name = 'Author', @capture_instance = 'dbo_Author' -- disable CDC for the entire DB -- this removes all CDC data, so be carefull exec sys.sp_cdc_disable_db SyntaxHighlighter.config.clipboardSwf = 'http://alexgorbatchev.com/pub/sh/2.0.320/scripts/clipboard.swf'; SyntaxHighlighter.all();

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• Overview of Microsoft SQL Server 2008 Upgrade Advisor

  - by Akshay Deep Lamba

  Problem Like most organizations, we are planning to upgrade our database server from SQL Server 2005 to SQL Server 2008. I would like to know is there an easy way to know in advance what kind of issues one may encounter when upgrading to a newer version of SQL Server? One way of doing this is to use the Microsoft SQL Server 2008 Upgrade Advisor to plan for upgrades from SQL Server 2000 or SQL Server 2005. In this tip we will take a look at how one can use the SQL Server 2008 Upgrade Advisor to identify potential issues before the upgrade. Solution SQL Server 2008 Upgrade Advisor is a free tool designed by Microsoft to identify potential issues before upgrading your environment to a newer version of SQL Server. Below are prerequisites which need to be installed before installing the Microsoft SQL Server 2008 Upgrade Advisor. Prerequisites for Microsoft SQL Server 2008 Upgrade Advisor .Net Framework 2.0 or a higher version Windows Installer 4.5 or a higher version Windows Server 2003 SP 1 or a higher version, Windows Server 2008, Windows XP SP2 or a higher version, Windows Vista Download SQL Server 2008 Upgrade Advisor You can download SQL Server 2008 Upgrade Advisor from the following link. Once you have successfully installed Upgrade Advisor follow the below steps to see how you can use this tool to identify potential issues before upgrading your environment. 1. Click Start -> Programs -> Microsoft SQL Server 2008 -> SQL Server 2008 Upgrade Advisor. 2. Click Launch Upgrade Advisor Analysis Wizard as highlighted below to open the wizard. 2. On the wizard welcome screen click Next to continue. 3. In SQL Server Components screen, enter the Server Name and click the Detect button to identify components which need to be analyzed and then click Next to continue with the wizard. 4. In Connection Parameters screen choose Instance Name, Authentication and then click Next to continue with the wizard. 5. In SQL Server Parameters wizard screen select the Databases which you want to analysis, trace files if any and SQL batch files if any.  Then click Next to continue with the wizard. 6. In Reporting Services Parameters screen you can specify the Reporting Server Instance name and then click next to continue with the wizard. 7. In Analysis Services Parameters screen you can specify an Analysis Server Instance name and then click Next to continue with the wizard. 8. In Confirm Upgrade Advisor Settings screen you will be able to see a quick summary of the options which you have selected so far. Click Run to start the analysis. 9. In Upgrade Advisor Progress screen you will be able to see the progress of the analysis. Basically, the upgrade advisor runs predefined rules which will help to identify potential issues that can affect your environment once you upgrade your server from a lower version of SQL Server to SQL Server 2008. 10. In the below snippet you can see that Upgrade Advisor has completed the analysis of SQL Server, Analysis Services and Reporting Services. To see the output click the Launch Report button at the bottom of the wizard screen. 11. In View Report screen you can see a summary of issues which can affect you once you upgrade. To learn more about each issue you can expand the issue and read the detailed description as shown in the below snippet.

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• Running & Managing Concurrent Queries in SQL Developer

  - by thatjeffsmith

  We’ve all been there – you’ve managed to write a query that takes longer than a few seconds to execute. Tuning aside, sometimes it takes longer than you want for a query to run. So what’s a SQL Developer user to do? I say, keep going! While you’re waiting for your query to finish, there’s no reason why you can’t continue on with your work. If you need to execute something else in a worksheet, there’s no reason to launch a 2nd or 3rd copy of SQL Developer. Just open an un-shared worksheet. Now while you’ve got 1 or more queries running, you can easily get yourself into a situation where you’re not sure what’s running where. Or maybe you want to cancel a query or just check how long something’s been running. Just open the Task Progress Panel If a query or task in SQL Developer takes more than 3-5 seconds, it will appear in the Task Progress panel. You can then watch the throbbers go back and forth while you sip your coffee/soda/Red Bull. Run a query, spawn a new worksheet, run another query, watch them in the Task Progress panel. Kudos and thanks to @leight0nn for helping me get the title of this post right If you’re looking for help in managing and monitoring sessions in general, check out this post.

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• Should we be able to deploy a single package to the SSIS Catalog?

  - by jamiet

  My buddy Sutha Thiru sent me an email recently asking about my opinion on a particular nuance of the project deployment model in SQL Server Integration Services (SSIS) 2012 and I’d like to share my response as I think it warrants a wider discussion. Sutha asked: Jamie What is your take on this? http://www.mattmasson.com/index.php/2012/07/can-i-deploy-a-single-ssis-package-from-my-project-to-the-ssis-catalog/ Overnight I was talking to Matt who confirmed that they got no plans to change the deployment model. For example if we have following scenrio how do we do deploy? Sprint 1 Pkg1, 2 & 3 has been developed and deployed to UAT. Once signed off its been deployed to Live. Sprint 2 Pkg 4 & 5 been developed. During this time users raised a bug on Pkg2. We want to make the change to Pkg2 and deploy that to UAT and eventually to LIVE without releasing Pkg 4 &5. How do we do it? Matt pointed me to his blog entry which I have seen before . http://www.mattmasson.com/index.php/2012/02/thoughts-on-branching-strategies-for-ssis-projects/ Thanks Sutha My response: Personally, even though I've experienced the exact problem you just outlined, I agree with the current approach. I steadfastly believe that there should not be a way for an unscrupulous developer to slide in a new version of a package under the covers. Deploying .ispac files brings a degree of rigour to your operational processes. Yes, that means that we as SSIS developers are going to have to get better at using source control and branching properly but that is no bad thing in my opinion. Claiming to be proper "developers" is a bit of a cheap claim if we don't even do the fundamentals correctly. I would be interested in the thoughts of others who have used the project deployment model. Do you agree with my point of view? @Jamiet

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• How do I restore a database on a remote SQL server 2005 from a local backup?

  - by MatsT

  I have been given access to (parts of) a remote SQL Server 2005 with SQL Server authentication in order to be able to make changes to a database without involving other people who is not working on the project. The database have been created on my local machine. Is there any way to restore the remote database from a backup file on my local computer? I do not currently have access to the filesystem on the remote server. EDIT: To clarify, the access I have is that i can log in to the server via the SQL Server Management Studio. I have one connection to my local database server and one connection to the remote server. What I basically want to do is copy the database from one connection to the other.

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• How do I restore a database on a remote SQL server 2005 from a local backup?

  - by MatsT

  I have been given access to (parts of) a remote SQL Server 2005 with SQL Server authentication in order to be able to make changes to a database without involving other people who is not working on the project. The database have been created on my local machine. Is there any way to restore the remote database from a backup file on my local computer? I do not currently have access to the filesystem on the remote server. EDIT: To clarify, the access I have is that i can log in to the server via the SQL Server Management Studio. I have one connection to my local database server and one connection to the remote server. What I basically want to do is copy the database from one connection to the other.

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• how to troubleshoot sql server issues

  - by joe

  i have an ASP .net application with sql server database, and i am wondering if you can give your ideas on how to troubleshoot the following issue: i can insert / update / delete from any table, but i have one page that uses transactions to insert into different tables. the c# code is correct and very simple, but it fails. i used the sql profiler to see how my app interacts with the DB, especially that the app is using stored procedures, i can catch the exec procedure statement and run it manually from SSMS and it works fine, but the same stored procedure fails from the application!!! which lead me to think that issue is coming from the user account and settings, i am no expert in sql server and wondering if anyone can explain how to verify the required settings for user account. thanks EDIT: in web.config here is how i reference my connection <connectionStrings> <add name="Conn" connectionString="Data Source=localhost;Initial Catalog=myDB;Persist Security Info=True;User ID=DbUser;Password=password1254_3" providerName="System.Data.SqlClient"> </connectionstring> EDIT: i will try to describe the process here: 1- i begin a transaction 2- i call a stored proc to insert (which succeeds) and return the scope identity ( that will be used in the next step) 3- i call another stored procedure to insert some more info + scope identity from step 2, which is a foreign key here 4- i get error, foreign key violation 5- transaction rolled back, now tables empty again... thanks

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• PowerShell & SQL Compare

  - by Grant Fritchey

  Just a quick blog post to share a couple of scripts for using PowerShell to call SQL Compare. This is an example from my session at SQL in the City on setting up a sandbox development process. This just runs a compare between a set of scripts and a database and deploys it. set-Location “c:\Program Files (x86)\Red Gate\SQL Compare 10\”; ./sqlcompare /s2:DOJO /db2:MovieManagement_Sandbox /sourcecontrol1 /vu1:grant /vp1:12345 /r1:HEAD /sfx:scripts.xml /sync /mfx:migrations.xml /verbose; I would not recommend using the /verbose output for real automation, but I’m showing off how the tool works. This particular script does a compare straight from source control to a database on my server. You can use variables where I’ve hard coded. That’s it. Works great. Just wanted to share it out there. I have others that I’ll track down and put up here.  

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• SQL Server 2008R2 Express: which is the users limit in a real case scenario?

  - by PressPlayOnTape

  I know that sql server express has not a user limit, and every application has a different way to load/stress the server. But let's take "a typical accounting software", where users input some record, retrieve some data and from time to time they make some custom big queries. May someone share its own experience and tell me which is the limit of users that can realistically use a sql server express instance in this scenario? I am looking for an indicative idea, like (as an example): "I had a company with an average of 40 users logged in and the application was working ok on sql server express, but when the users become 60 the application started to seem non repsonsive" (please note this sentence is pure imagination, I just wrote it as an example).

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• First Shard for SQL Azure and SQL Server

  - by Herve Roggero

  That's it!!!!! It's ready to go and be tested, abused and improved! It requires .NET 4.0 and uses some cool technologies, like caching (the new System.Runtime.Caching) and the Task Parallel Library (System.Threading.Tasks). With this library you can: Define a shard of 1, 2 or 100 SQL databases (a mix of SQL Server and SQL Azure) Read from the shard in parallel or sequentially, and cache resultsets Update, Delete a record from the shard Insert records quickly in the shard with a round-robin load Reset the cache You can download the source code and a sample application here: http://enzosqlshard.codeplex.com/  Note about the breadcrumbs: I had to add a connection GUID in order for the library to know which database a record came from. The GUID is currently calculated on the fly in the library using some of the parameters of the connection string. The GUID is also dynamically added to the result set so the client can pass it back to the library. I am curious to get your feedback on this approach. ** Correction from my previous post: this is a library for a Horizontal Partition Shard (HPS): tables are split across databases horizontally. So in essence, the tables need to have the same schema across the databases.

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• TDD with SQL and data manipulation functions

  - by Xophmeister

  While I'm a professional programmer, I've never been formally trained in software engineering. As I'm frequently visiting here and SO, I've noticed a trend for writing unit tests whenever possible and, as my software gets more complex and sophisticated, I see automated testing as a good idea in aiding debugging. However, most of my work involves writing complex SQL and then processing the output in some way. How would you write a test to ensure your SQL was returning the correct data, for example? Then, say if the data wasn't under your control (e.g., that of a 3rd party system), how can you efficiently test your processing routines without having to hand write reams of dummy data? The best solution I can think of is making views of the data that, together, cover most cases. I can then join those views with my SQL to see if it's returning the correct records and manually process the views to see if my functions, etc. are doing what they're supposed to. Still, it seems excessive and flakey; particularly finding data to test against...

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• Options for transparent data encryption on SQL 2005 and 2008 DBs.

  - by Dan

  Recently, in Massachusetts a law was passed (rather silently) that data containing personally identifiable information, must be encrypted. PII is defined by the state, as containing the residents first and last name, in combination with either, A. SSN B. drivers license or ID card # C. Debit or CC # Due to the nature of the software we make, all of our clients use SQL as the backend. Typically servers will be running SQl2005 Standard or above, sometimes SQL 2008. Almost all client machines use SQL2005 Express. We use replication between client and server. Unfortunately, to get TDE you need to have SQL Enterprise on each machine, which is absolutely not an option. I'm looking for recommendations of products that will encrypt a DB. Right now, I'm not interested in whole disk encryption at all.

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