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• C++ Template Classes and Copy Construction

  - by themoondothshine

  Is there any way I can construct an new object from the given object if the template parameters of both objects are identical at run-time? For example: I have a template class with the declaration: template<typename _Type1, typename _Type2> class Object; Next, I have two instantiations of the template: template class Object<char, int>; template class Object<wchar_t, wint_t>; Now, I want to write a member function such as: template<typename _Type1, typename _Type2> Object<char, int> Object<_Type1, _Type2>::toCharObject() { if(__gnu_cxx::__are_same<_Type1, char>::__value) return *this; else { //Perform some kind of conversion and return an Object<char, int> } } I have tried a couple of techniques, such as using __gnu_cxx::__enable_if<__gnu_cxx::__are_same<_Type1, char>::__value, _Type1>::__type in a copy constructor for the Oject class, but I keep running into the error: error: conversion from ‘Object<wchar_t, wint_t>’ to non-scalar type ‘Object<char, int>’ requested Is there no way I can do this? Any help will be greatly appreciated!

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• SQL SERVER – Simple Example to Configure Resource Governor – Introduction to Resource Governor

  - by pinaldave

  Let us jump right away with question and answer mode. What is resource governor? Resource Governor is a feature which can manage SQL Server Workload and System Resource Consumption. We can limit the amount of CPU and memory consumption by limiting /governing /throttling on the SQL Server. Why is resource governor required? If there are different workloads running on SQL Server and each of the workload needs different resources or when workloads are competing for resources with each other and affecting the performance of the whole server resource governor is a very important task. What will be the real world example of need of resource governor? Here are two simple scenarios where the resource governor can be very useful. Scenario 1: A server which is running OLTP workload and various resource intensive reports on the same server. The ideal situation is where there are two servers which are data synced with each other and one server runs OLTP transactions and the second server runs all the resource intensive reports. However, not everybody has the luxury to set up this kind of environment. In case of the situation where reports and OLTP transactions are running on the same server, limiting the resources to the reporting workload it can be ensured that OTLP’s critical transaction is not throttled. Scenario 2: There are two DBAs in one organization. One DBA A runs critical queries for business and another DBA B is doing maintenance of the database. At any point in time the DBA A’s work should not be affected but at the same time DBA B should be allowed to work as well. The ideal situation is that when DBA B starts working he get some resources but he can’t get more than defined resources. Does SQL Server have any default resource governor component? Yes, SQL Server have two by default created resource governor component. 1) Internal –This is used by database engine exclusives and user have no control. 2) Default – This is used by all the workloads which are not assigned to any other group. What are the major components of the resource governor? Resource Pools Workload Groups Classification In simple words here is what the process of resource governor is. Create resource pool Create a workload group Create classification function based on the criteria specified Enable Resource Governor with classification function Let me further explain you the same with graphical image. Is it possible to configure resource governor with T-SQL? Yes, here is the code for it with explanation in between. Step 0: Here we are assuming that there are separate login accounts for Reporting server and OLTP server. /*----------------------------------------------- Step 0: (Optional and for Demo Purpose) Create Two User Logins 1) ReportUser, 2) PrimaryUser Use ReportUser login for Reports workload Use PrimaryUser login for OLTP workload -----------------------------------------------*/ Step 1: Creating Resource Pool We are creating two resource pools. 1) Report Server and 2) Primary OLTP Server. We are giving only a few resources to the Report Server Pool as described in the scenario 1 the other server is mission critical and not the report server. ----------------------------------------------- -- Step 1: Create Resource Pool ----------------------------------------------- -- Creating Resource Pool for Report Server CREATE RESOURCE POOL ReportServerPool WITH ( MIN_CPU_PERCENT=0, MAX_CPU_PERCENT=30, MIN_MEMORY_PERCENT=0, MAX_MEMORY_PERCENT=30) GO -- Creating Resource Pool for OLTP Primary Server CREATE RESOURCE POOL PrimaryServerPool WITH ( MIN_CPU_PERCENT=50, MAX_CPU_PERCENT=100, MIN_MEMORY_PERCENT=50, MAX_MEMORY_PERCENT=100) GO Step 2: Creating Workload Group We are creating two workloads each mapping to each of the resource pool which we have just created. ----------------------------------------------- -- Step 2: Create Workload Group ----------------------------------------------- -- Creating Workload Group for Report Server CREATE WORKLOAD GROUP ReportServerGroup USING ReportServerPool ; GO -- Creating Workload Group for OLTP Primary Server CREATE WORKLOAD GROUP PrimaryServerGroup USING PrimaryServerPool ; GO Step 3: Creating user defiled function which routes the workload to the appropriate workload group. In this example we are checking SUSER_NAME() and making the decision of Workgroup selection. We can use other functions such as HOST_NAME(), APP_NAME(), IS_MEMBER() etc. ----------------------------------------------- -- Step 3: Create UDF to Route Workload Group ----------------------------------------------- CREATE FUNCTION dbo.UDFClassifier() RETURNS SYSNAME WITH SCHEMABINDING AS BEGIN DECLARE @WorkloadGroup AS SYSNAME IF(SUSER_NAME() = 'ReportUser') SET @WorkloadGroup = 'ReportServerGroup' ELSE IF (SUSER_NAME() = 'PrimaryServerPool') SET @WorkloadGroup = 'PrimaryServerGroup' ELSE SET @WorkloadGroup = 'default' RETURN @WorkloadGroup END GO Step 4: In this final step we enable the resource governor with the classifier function created in earlier step 3. ----------------------------------------------- -- Step 4: Enable Resource Governer -- with UDFClassifier ----------------------------------------------- ALTER RESOURCE GOVERNOR WITH (CLASSIFIER_FUNCTION=dbo.UDFClassifier); GO ALTER RESOURCE GOVERNOR RECONFIGURE GO Step 5: If you are following this demo and want to clean up your example, you should run following script. Running them will disable your resource governor as well delete all the objects created so far. ----------------------------------------------- -- Step 5: Clean Up -- Run only if you want to clean up everything ----------------------------------------------- ALTER RESOURCE GOVERNOR WITH (CLASSIFIER_FUNCTION = NULL) GO ALTER RESOURCE GOVERNOR DISABLE GO DROP FUNCTION dbo.UDFClassifier GO DROP WORKLOAD GROUP ReportServerGroup GO DROP WORKLOAD GROUP PrimaryServerGroup GO DROP RESOURCE POOL ReportServerPool GO DROP RESOURCE POOL PrimaryServerPool GO ALTER RESOURCE GOVERNOR RECONFIGURE GO I hope this introductory example give enough light on the subject of Resource Governor. In future posts we will take this same example and learn a few more details. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: Resource Governor

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• Tuning Red Gate: #4 of Some

  - by Grant Fritchey

  First time connecting to these servers directly (keys to the kingdom, bwa-ha-ha-ha. oh, excuse me), so I'm going to take a look at the server properties, just to see if there are any issues there. Max memory is set, cool, first possible silly mistake clear. In fact, these look to be nicely set up. Oh, I'd like to see the ANSI Standards set by default, but it's not a big deal. The default location for database data is the F:\ drive, where I saw all the activity last time. Cool, the people maintaining the servers in our company listen, parallelism threshold is set to 35 and optimize for ad hoc is enabled. No shocks, no surprises. The basic setup is appropriate. On to the problem database. Nothing wrong in the properties. The database is in SIMPLE recovery, but I think it's a reporting system, so no worries there. Again, I'd prefer to see the ANSI settings for connections, but that's the worst thing I can see. Time to look at the queries, tables, indexes and statistics because all the information I've collected over the last several days suggests that we're not looking at a systemic problem (except possibly not enough memory), but at the traditional tuning issues. I just want to note that, I started looking at the system, not the queries. So should you when tuning your environment. I know, from the data collected through SQL Monitor, what my top poor performing queries are, and the most frequently called, etc. I'm starting with the most frequently called. I'm going to get the execution plan for this thing out of the cache (although, with the cache dumping constantly, I might not get it). And it's not there. Called 1.3 million times over the last 3 days, but it's not in cache. Wow. OK. I'll see what's in cache for this database: SELECT  deqs.creation_time,         deqs.execution_count,         deqs.max_logical_reads,         deqs.max_elapsed_time,         deqs.total_logical_reads,         deqs.total_elapsed_time,         deqp.query_plan,         SUBSTRING(dest.text, (deqs.statement_start_offset / 2) + 1,                   (deqs.statement_end_offset - deqs.statement_start_offset) / 2                   + 1) AS QueryStatement FROM    sys.dm_exec_query_stats AS deqs         CROSS APPLY sys.dm_exec_sql_text(deqs.sql_handle) AS dest         CROSS APPLY sys.dm_exec_query_plan(deqs.plan_handle) AS deqp WHERE   dest.dbid = DB_ID('Warehouse') AND deqs.statement_end_offset > 0 AND deqs.statement_start_offset > 0 ORDER BY deqs.max_logical_reads DESC ; And looking at the most expensive operation, we have our first bad boy: Multiple table scans against very large sets of data and a sort operation. a sort operation? It's an insert. Oh, I see, the table is a heap, so it's doing an insert, then sorting the data and then inserting into the primary key. First question, why isn't this a clustered index? Let's look at some more of the queries. The next one is deceiving. Here's the query plan: You're thinking to yourself, what's the big deal? Well, what if I told you that this thing had 8036318 reads? I know, you're looking at skinny little pipes. Know why? Table variable. Estimated number of rows = 1. Actual number of rows. well, I'm betting several more than one considering it's read 8 MILLION pages off the disk in a single execution. We have a serious and real tuning candidate. Oh, and I missed this, it's loading the table variable from a user defined function. Let me check, let me check. YES! A multi-statement table valued user defined function. And another tuning opportunity. This one's a beauty, seriously. Did I also mention that they're doing a hash against all the columns in the physical table. I'm sure that won't lead to scans of a 500,000 row table, no, not at all. OK. I lied. Of course it is. At least it's on the top part of the Loop which means the scan is only executed once. I just did a cursory check on the next several poor performers. all calling the UDF. I think I found a big tuning opportunity. At this point, I'm typing up internal emails for the company. Someone just had their baby called ugly. In addition to a series of suggested changes that we need to implement, I'm also apologizing for being such an unkind monster as to question whether that third eye & those flippers belong on such an otherwise lovely child.

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• SQL SERVER – Weekly Series – Memory Lane – #006

  - by pinaldave

  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. 2006 This was my very first year of blogging so I was every day learning something new. As I have said many times, that blogging was never an intention. I had really not understood what exactly I am working on or beginning when I was beginning blogging in 2006. I had never knew that my life was going to change forever, once I started blogging. When I look back all of this year, I am happy that we are here together. 2007 IT Outsourcing to India – Top 10 Reasons Companies Outsource Outsourcing is about trust, collaboration and success. Helping other countries in need has been always the course of mankind, outsourcing is nothing different then that. With information technology and process improvements increasing the complexity, costs and skills required to accomplish routine tasks as well as challenging complex tasks, companies are outsourcing such tasks to providers who have the expertise to perform them at lower costs , with greater value and quality outcome. UDF – Remove Duplicate Chars From String This was a very interesting function I wrote in my early career. I am still using this function when I have to remove duplicate chars from strings. I have yet to come across a scenario where it does not work so I keep on using it till today. Please leave a comment if there is any better solution to this problem. FIX : Error : 3702 Cannot drop database because it is currently in use This is a very generic error when DROP Database is command is executed and the database is not dropped. The common mistake user is kept the connection open with this database and trying to drop the database. The database cannot be dropped if there is any other connection open along with it. It is always a good idea to take database in single user mode before dropping it. Here is the quick tutorial regarding how to bring the database in single user mode: Using T-SQL | Using SSMS. 2008 Install SQL Server 2008 – How to Upgrade to SQL Server 2008 – Installation Tutorial This was indeed one of the most popular articles in SQL Server 2008. Lots of people wanted to learn how to install SQL SErver 2008 but they were facing various issues while installation. I build this tutorial which becomes reference points for many. Default Collation of SQL Server 2008 What is the collation of SQL Server 2008 default installations? I often see this question confusing many experienced developers as well. Well the answer is in following image. Ahmedabad SQL Server User Group Meeting – November 2008 User group meetings are fun, now a days I am going to User Group meetings every week but there was a case when I have been just a beginner on this subject. The bug of the community was caught on me years ago when I started to present in Ahmedabad and Gandhinagar SQ LServer User Groups. 2009 Validate an XML document in TSQL using XSD My friend Jacob Sebastian wrote an excellent article on the subject XML and XSD. Because of the ‘eXtensible’ nature of XML (eXtensible Markup Language), often there is a requirement to restrict and validate the content of an XML document to a pre-defined structure and values. XSD (XML Schema Definition Language) is the W3C recommended language for describing and validating XML documents. SQL Server implements XSD as XML Schema Collections. Star Join Query Optimization At present, when queries are sent to very large databases, millions of rows are returned. Also the users have to go through extended query response times when joining multiple tables are involved with such queries. ‘Star Join Query Optimization’ is a new feature of SQL Server 2008 Enterprise Edition. This mechanism uses bitmap filtering for improving the performance of some types of queries by the effective retrieval of rows from fact tables. 2010 These puzzles are very interesting and intriguing – there was lots of interest on this subject. If you have free time this weekend. You may want to try them out. SQL SERVER – Challenge – Puzzle – Usage of FAST Hint (Solution)  SQL SERVER – Puzzle – Challenge – Error While Converting Money to Decimal (Solution)  SQL SERVER – Challenge – Puzzle – Why does RIGHT JOIN Exists (Open)  Additionally, I had great fun presenting SQL Server Performance Tuning seminar at fantastic locations in Hyderabad. Installing AdventeWorks Database This has been the most popular request I have received on my blog. Here is the quick video about how one can install AdventureWorks. 2011 Effect of SET NOCOUNT on @@ROWCOUNT There was an interesting incident once while I was presenting a session. I wrote a code and suddenly 10 hands went up in the air.  This was a bit surprise to me as I do not know why they all got alerted. I assumed that there should be something wrong with either project, screen or my display. However the real reason was very interesting – I suggest you read the complete blog post to understand this interesting scenario. Error: Deleting Offline Database and Creating the Same Name This is very interesting because once a user deletes the offline database the MDF and LDF file still exists and if the user attempts to create a new database with the same name it will give error. I found this very interesting and the blog explains the concept very quickly. Have you ever faced a similar situation? 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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• SQL CLR Stored Procedure and Web Service

  - by Nathan

  I am current working on a task in which I am needing to call a method in a web service from a CLR stored procedure. A bit of background: Basically, I have a task that requires ALOT of crunching. If done strictly in SQL, it takes somewhere around 30-45 mins to process. If I pull the same process into code, I can get it complete in seconds due to being able to optimize the processing so much more efficiently. The only problem is that I have to have this process set as an automated task in SQL Server. In that vein, I have exposed the process as a web service (I use it for other things as well) and want the SQL CLR sproc to consume the service and execute the code. This allows me to have my automated task. The problem: I have read quite a few different topics regarding how to consume a web service in a CLR Sproc and have done so effectivly. Here is an example of what I have followed. http://blog.hoegaerden.be/2008/11/11/calling-a-web-service-from-sql-server-2005/ I can get this example working without any issues. However, whenever I pair this process w/ a Web Service method that involves a database call, I get the following exceptions (depending upon whether or not I wrap in a try / catch): Msg 10312, Level 16, State 49, Procedure usp_CLRRunDirectSimulationAndWriteResults, Line 0 .NET Framework execution was aborted. The UDP/UDF/UDT did not revert thread token. or Msg 6522, Level 16, State 1, Procedure MyStoredProc , Line 0 A .NET Framework error occurred during execution of user defined routine or aggregate 'MyStoredProc': System.Security.SecurityException: Request for the permission of type 'System.Security.Permissions.EnvironmentPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed. System.Security.SecurityException: at System.Security.CodeAccessSecurityEngine.Check(Object demand, StackCrawlMark& stackMark, Boolean isPermSet) at System.Security.CodeAccessPermission.Demand() at System.Net.CredentialCache.get_DefaultCredentials() at System.Web.Services.Protocols.WebClientProtocol.set_UseDefaultCredentials(Boolean value) at MyStoredProc.localhost.MPWebService.set_UseDefaultCredentials(Boolean Value) at MyStoredProclocalhost.MPWebService..ctor() at MyStoredProc.StoredProcedures.MyStoredProc(String FromPostCode, String ToPostCode) I am sure this is a permission issue, but I can't, for the life of me get it working. I have attempted using impersonation in the CLR sproc and a few other things. Any suggestions? What am I missing?

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• Simple Self Join Query Bad Performance

  - by user1514042

  Could anyone advice on how do I improve the performance of the following query. Note, the problem seems to be caused by where clause. Data (table contains a huge set of rows - 500K+, the set of parameters it's called with assums the return of 2-5K records per query, which takes 8-10 minutes currently): USE [SomeDb] GO SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[Data]( [x] [money] NOT NULL, [y] [money] NOT NULL, CONSTRAINT [PK_Data] PRIMARY KEY CLUSTERED ( [x] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO The Query select top 10000 s.x as sx, e.x as ex, s.y as sy, e.y as ey, e.y - s.y as y_delta, e.x - s.x as x_delta from Data s inner join Data e on e.x > s.x and e.x - s.x between xFrom and xTo --where e.y - s.y > @yDelta -- when uncommented causes a huge delay Update 1 - Execution Plan <?xml version="1.0" encoding="utf-16"?> <ShowPlanXML xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" Version="1.2" Build="11.0.2100.60" xmlns="http://schemas.microsoft.com/sqlserver/2004/07/showplan"> <BatchSequence> <Batch> <Statements> <StmtSimple StatementCompId="1" StatementEstRows="100" StatementId="1" StatementOptmLevel="FULL" StatementOptmEarlyAbortReason="GoodEnoughPlanFound" StatementSubTreeCost="0.0263655" StatementText="select top 100&#xD;&#xA;s.x as sx,&#xD;&#xA;e.x as ex,&#xD;&#xA;s.y as sy,&#xD;&#xA;e.y as ey,&#xD;&#xA;e.y - s.y as y_delta,&#xD;&#xA;e.x - s.x as x_delta&#xD;&#xA;from Data s &#xD;&#xA; inner join Data e&#xD;&#xA; on e.x &gt; s.x and e.x - s.x between 100 and 105&#xD;&#xA;where e.y - s.y &gt; 0.01&#xD;&#xA;" StatementType="SELECT" QueryHash="0xAAAC02AC2D78CB56" QueryPlanHash="0x747994153CB2D637" RetrievedFromCache="true"> <StatementSetOptions ANSI_NULLS="true" ANSI_PADDING="true" ANSI_WARNINGS="true" ARITHABORT="true" CONCAT_NULL_YIELDS_NULL="true" NUMERIC_ROUNDABORT="false" QUOTED_IDENTIFIER="true" /> <QueryPlan DegreeOfParallelism="0" NonParallelPlanReason="NoParallelPlansInDesktopOrExpressEdition" CachedPlanSize="24" CompileTime="13" CompileCPU="13" CompileMemory="424"> <MemoryGrantInfo SerialRequiredMemory="0" SerialDesiredMemory="0" /> <OptimizerHardwareDependentProperties EstimatedAvailableMemoryGrant="52199" EstimatedPagesCached="14561" EstimatedAvailableDegreeOfParallelism="4" /> <RelOp AvgRowSize="55" EstimateCPU="1E-05" EstimateIO="0" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="100" LogicalOp="Compute Scalar" NodeId="0" Parallel="false" PhysicalOp="Compute Scalar" EstimatedTotalSubtreeCost="0.0263655"> <OutputList> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="x" /> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="y" /> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="x" /> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="y" /> <ColumnReference Column="Expr1004" /> <ColumnReference Column="Expr1005" /> </OutputList> <ComputeScalar> <DefinedValues> <DefinedValue> <ColumnReference Column="Expr1004" /> <ScalarOperator ScalarString="[SomeDb].[dbo].[Data].[y] as [e].[y]-[SomeDb].[dbo].[Data].[y] as [s].[y]"> <Arithmetic Operation="SUB"> <ScalarOperator> <Identifier> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="y" /> </Identifier> </ScalarOperator> <ScalarOperator> <Identifier> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="y" /> </Identifier> </ScalarOperator> </Arithmetic> </ScalarOperator> </DefinedValue> <DefinedValue> <ColumnReference Column="Expr1005" /> <ScalarOperator ScalarString="[SomeDb].[dbo].[Data].[x] as [e].[x]-[SomeDb].[dbo].[Data].[x] as [s].[x]"> <Arithmetic Operation="SUB"> <ScalarOperator> <Identifier> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="x" /> </Identifier> </ScalarOperator> <ScalarOperator> <Identifier> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="x" /> </Identifier> </ScalarOperator> </Arithmetic> </ScalarOperator> </DefinedValue> </DefinedValues> <RelOp AvgRowSize="39" EstimateCPU="1E-05" EstimateIO="0" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="100" LogicalOp="Top" NodeId="1" Parallel="false" PhysicalOp="Top" EstimatedTotalSubtreeCost="0.0263555"> <OutputList> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="x" /> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="y" /> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="x" /> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="y" /> </OutputList> <RunTimeInformation> <RunTimeCountersPerThread Thread="0" ActualRows="100" ActualEndOfScans="1" ActualExecutions="1" /> </RunTimeInformation> <Top RowCount="false" IsPercent="false" WithTies="false"> <TopExpression> <ScalarOperator ScalarString="(100)"> <Const ConstValue="(100)" /> </ScalarOperator> </TopExpression> <RelOp AvgRowSize="39" EstimateCPU="151828" EstimateIO="0" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="100" LogicalOp="Inner Join" NodeId="2" Parallel="false" PhysicalOp="Nested Loops" EstimatedTotalSubtreeCost="0.0263455"> <OutputList> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="x" /> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="y" /> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="x" /> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="y" /> </OutputList> <RunTimeInformation> <RunTimeCountersPerThread Thread="0" ActualRows="100" ActualEndOfScans="0" ActualExecutions="1" /> </RunTimeInformation> <NestedLoops Optimized="false"> <OuterReferences> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="x" /> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="y" /> </OuterReferences> <RelOp AvgRowSize="23" EstimateCPU="1.80448" EstimateIO="3.76461" EstimateRebinds="0" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="1" LogicalOp="Clustered Index Scan" NodeId="3" Parallel="false" PhysicalOp="Clustered Index Scan" EstimatedTotalSubtreeCost="0.0032831" TableCardinality="1640290"> <OutputList> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="x" /> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="y" /> </OutputList> <RunTimeInformation> <RunTimeCountersPerThread Thread="0" ActualRows="15225" ActualEndOfScans="0" ActualExecutions="1" /> </RunTimeInformation> <IndexScan Ordered="false" ForcedIndex="false" ForceScan="false" NoExpandHint="false"> <DefinedValues> <DefinedValue> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="x" /> </DefinedValue> <DefinedValue> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="y" /> </DefinedValue> </DefinedValues> <Object Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Index="[PK_Data]" Alias="[e]" IndexKind="Clustered" /> </IndexScan> </RelOp> <RelOp AvgRowSize="23" EstimateCPU="0.902317" EstimateIO="1.88387" EstimateRebinds="1" EstimateRewinds="0" EstimatedExecutionMode="Row" EstimateRows="100" LogicalOp="Clustered Index Seek" NodeId="4" Parallel="false" PhysicalOp="Clustered Index Seek" EstimatedTotalSubtreeCost="0.0263655" TableCardinality="1640290"> <OutputList> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="x" /> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="y" /> </OutputList> <RunTimeInformation> <RunTimeCountersPerThread Thread="0" ActualRows="100" ActualEndOfScans="15224" ActualExecutions="15225" /> </RunTimeInformation> <IndexScan Ordered="true" ScanDirection="FORWARD" ForcedIndex="false" ForceSeek="false" ForceScan="false" NoExpandHint="false" Storage="RowStore"> <DefinedValues> <DefinedValue> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="x" /> </DefinedValue> <DefinedValue> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="y" /> </DefinedValue> </DefinedValues> <Object Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Index="[PK_Data]" Alias="[s]" IndexKind="Clustered" /> <SeekPredicates> <SeekPredicateNew> <SeekKeys> <EndRange ScanType="LT"> <RangeColumns> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="x" /> </RangeColumns> <RangeExpressions> <ScalarOperator ScalarString="[SomeDb].[dbo].[Data].[x] as [e].[x]"> <Identifier> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="x" /> </Identifier> </ScalarOperator> </RangeExpressions> </EndRange> </SeekKeys> </SeekPredicateNew> </SeekPredicates> <Predicate> <ScalarOperator ScalarString="([SomeDb].[dbo].[Data].[x] as [e].[x]-[SomeDb].[dbo].[Data].[x] as [s].[x])&gt;=($100.0000) AND ([SomeDb].[dbo].[Data].[x] as [e].[x]-[SomeDb].[dbo].[Data].[x] as [s].[x])&lt;=($105.0000) AND ([SomeDb].[dbo].[Data].[y] as [e].[y]-[SomeDb].[dbo].[Data].[y] as [s].[y])&gt;(0.01)"> <Logical Operation="AND"> <ScalarOperator> <Compare CompareOp="GE"> <ScalarOperator> <Arithmetic Operation="SUB"> <ScalarOperator> <Identifier> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="x" /> </Identifier> </ScalarOperator> <ScalarOperator> <Identifier> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="x" /> </Identifier> </ScalarOperator> </Arithmetic> </ScalarOperator> <ScalarOperator> <Const ConstValue="($100.0000)" /> </ScalarOperator> </Compare> </ScalarOperator> <ScalarOperator> <Compare CompareOp="LE"> <ScalarOperator> <Arithmetic Operation="SUB"> <ScalarOperator> <Identifier> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="x" /> </Identifier> </ScalarOperator> <ScalarOperator> <Identifier> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="x" /> </Identifier> </ScalarOperator> </Arithmetic> </ScalarOperator> <ScalarOperator> <Const ConstValue="($105.0000)" /> </ScalarOperator> </Compare> </ScalarOperator> <ScalarOperator> <Compare CompareOp="GT"> <ScalarOperator> <Arithmetic Operation="SUB"> <ScalarOperator> <Identifier> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[e]" Column="y" /> </Identifier> </ScalarOperator> <ScalarOperator> <Identifier> <ColumnReference Database="[SomeDb]" Schema="[dbo]" Table="[Data]" Alias="[s]" Column="y" /> </Identifier> </ScalarOperator> </Arithmetic> </ScalarOperator> <ScalarOperator> <Const ConstValue="(0.01)" /> </ScalarOperator> </Compare> </ScalarOperator> </Logical> </ScalarOperator> </Predicate> </IndexScan> </RelOp> </NestedLoops> </RelOp> </Top> </RelOp> </ComputeScalar> </RelOp> </QueryPlan> </StmtSimple> </Statements> </Batch> </BatchSequence> </ShowPlanXML>

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• Workaround for datadude deployment bug - NullReferenceException

  - by jamiet

  I have come across a bug in Visual Studio 2010 Database Projects (aka datadude aka DPro aka Visual Studio Database Development Tools aka Visual Studio Team Edition for Database Professionals aka Juneau aka SQL Server Data Tools) that other people may encounter so, for the purposes of googling, I'm writing this blog post about it. Through my own googling I discovered that a Connect bug had already been raised about it (VS2010 Database project deploy - “SqlDeployTask” task failed unexpectedly, NullReferenceException), and coincidentally enough it was raised by my former colleague Tom Hunter (whom I have mentioned here before as the superhuman Tom Hunter) although it has not (at this time) received a reply from Microsoft. Tom provided a repro, namely that this syntactically valid function definition: CREATE FUNCTION [dbo].[Function1]()RETURNS TABLEASRETURN (    WITH cte AS (    SELECT 1 AS [c1]    FROM [$(Database3)].[dbo].[Table1]   )   SELECT 1 AS [c1]   FROM cte) would produce this nasty unhelpful error upon deployment: C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\v10.0\TeamData\Microsoft.Data.Schema.TSqlTasks.targets(120,5): Error MSB4018: The "SqlDeployTask" task failed unexpectedly.System.NullReferenceException: Object reference not set to an instance of an object.   at Microsoft.Data.Schema.Sql.SchemaModel.SqlModelComparerBase.VariableSubstitution(SqlScriptProperty propertyValue, IDictionary`2 variables, Boolean& isChanged)   at Microsoft.Data.Schema.Sql.SchemaModel.SqlModelComparerBase.ArePropertiesEqual(IModelElement source, IModelElement target, ModelPropertyClass propertyClass, ModelComparerConfiguration configuration)   at Microsoft.Data.Schema.SchemaModel.ModelComparer.CompareProperties(IModelElement sourceElement, IModelElement targetElement, ModelComparerConfiguration configuration, ModelComparisonChangeDefinition changes)   at Microsoft.Data.Schema.SchemaModel.ModelComparer.CompareElementsWithoutCompareName(IModelElement sourceElement, IModelElement targetElement, ModelComparerConfiguration configuration, Boolean parentExplicitlyIncluded, Boolean compareElementOnly, ModelComparisonResult result, ModelComparisonChangeDefinition changes)   at Microsoft.Data.Schema.SchemaModel.ModelComparer.CompareElementsWithSameType(IModelElement sourceElement, IModelElement targetElement, ModelComparerConfiguration configuration, ModelComparisonResult result, Boolean ignoreComparingName, Boolean parentExplicitlyIncluded, Boolean compareElementOnly, Boolean compareFromRootElement, ModelComparisonChangeDefinition& changes)   at Microsoft.Data.Schema.SchemaModel.ModelComparer.CompareChildren(IModelElement sourceElement, IModelElement targetElement, ModelComparerConfiguration configuration, Boolean parentExplicitlyIncluded, Boolean compareParentElementOnly, ModelComparisonResult result, ModelComparisonChangeDefinition changes, Boolean isComposing)   at Microsoft.Data.Schema.SchemaModel.ModelComparer.CompareElementsWithoutCompareName(IModelElement sourceElement, IModelElement targetElement, ModelComparerConfiguration configuration, Boolean parentExplicitlyIncluded, Boolean compareElementOnly, ModelComparisonResult result, ModelComparisonChangeDefinition changes)   at Microsoft.Data.Schema.SchemaModel.ModelComparer.CompareElementsWithSameType(IModelElement sourceElement, IModelElement targetElement, ModelComparerConfiguration configuration, ModelComparisonResult result, Boolean ignoreComparingName, Boolean parentExplicitlyIncluded, Boolean compareElementOnly, Boolean compareFromRootElement, ModelComparisonChangeDefinition& changes)   at Microsoft.Data.Schema.SchemaModel.ModelComparer.CompareChildren(IModelElement sourceElement, IModelElement targetElement, ModelComparerConfiguration configuration, Boolean parentExplicitlyIncluded, Boolean compareParentElementOnly, ModelComparisonResult result, ModelComparisonChangeDefinition changes, Boolean isComposing)   at Microsoft.Data.Schema.SchemaModel.ModelComparer.CompareElementsWithoutCompareName(IModelElement sourceElement, IModelElement targetElement, ModelComparerConfiguration configuration, Boolean parentExplicitlyIncluded, Boolean compareElementOnly, ModelComparisonResult result, ModelComparisonChangeDefinition changes)   at Microsoft.Data.Schema.SchemaModel.ModelComparer.CompareElementsWithSameType(IModelElement sourceElement, IModelElement targetElement, ModelComparerConfiguration configuration, ModelComparisonResult result, Boolean ignoreComparingName, Boolean parentExplicitlyIncluded, Boolean compareElementOnly, Boolean compareFromRootElement, ModelComparisonChangeDefinition& changes)   at Microsoft.Data.Schema.SchemaModel.ModelComparer.CompareAllElementsForOneType(ModelElementClass type, ModelComparerConfiguration configuration, ModelComparisonResult result, Boolean compareOrphanedElements)   at Microsoft.Data.Schema.SchemaModel.ModelComparer.CompareStore(ModelStore source, ModelStore target, ModelComparerConfiguration configuration)   at Microsoft.Data.Schema.Build.SchemaDeployment.CompareModels()   at Microsoft.Data.Schema.Build.SchemaDeployment.PrepareBuildPlan()   at Microsoft.Data.Schema.Build.SchemaDeployment.Execute(Boolean executeDeployment)   at Microsoft.Data.Schema.Build.SchemaDeployment.Execute()   at Microsoft.Data.Schema.Tasks.DBDeployTask.Execute()   at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute()   at Microsoft.Build.BackEnd.TaskBuilder.ExecuteInstantiatedTask(ITaskExecutionHost taskExecutionHost, TaskLoggingContext taskLoggingContext, TaskHost taskHost, ItemBucket bucket, TaskExecutionMode howToExecuteTask, Boolean& taskResult)   Done executing task "SqlDeployTask" -- FAILED.  Done building target "DspDeploy" in project "Lloyds.UKTax.DB.UKtax.dbproj" -- FAILED. Done executing task "CallTarget" -- FAILED.Done building target "DBDeploy" in project It turns out there are a certain set of circumstances that need to be met for this error to occur: The object being deployed is an inline function  (may also exist for multistatement and scalar functions - I haven't tested that) That object includes SQLCMD variable references The object has already been deployed successfully Just to reiterate that last bullet point, the error does not occur when you deploy the function for the first time, only on the subsequent deployment.   Luckily I have a direct line into a guy on the development team so I fired off an email on Friday evening and today (Monday) I received a reply back telling me that there is a simple fix, one simply has to remove the parentheses that wrap the SQL statement. So, in the case of Tom's repro, the function definition simpy has to be changed to: CREATE FUNCTION [dbo].[Function1]()RETURNS TABLEASRETURN --(    WITH cte AS (    SELECT 1 AS [c1]    FROM [$(Database3)].[dbo].[Table1]   )   SELECT 1 AS [c1]   FROM cte--) I have commented out the offending parentheses rather than removing them just to emphasize the point. Thereafter the function will deploy fine. I tested this out on my own project this morning and can confirm that this fix does indeed work.   I have been told that the bug CAN be reproduced in the Release Candidate (RC) 0 build of SQL Server Data Tools in SQL Server 2010 so am hoping that a fix makes it in for the Release-To-Manufacturing (RTM) build. Hope this helps @jamiet

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• Windows in StreamInsight: Hopping vs. Snapshot

  - by Roman Schindlauer

  Three weeks ago, we explained the basic concept of windows in StreamInsight: defining sets of events that serve as arguments for set-based operations, like aggregations. Today, we want to discuss the so-called Hopping Windows and compare them with Snapshot Windows. We will compare these two, because they can serve similar purposes with different behaviors; we will discuss the remaining window type, Count Windows, another time. Hopping (and its syntactic-sugar-sister Tumbling) windows are probably the most straightforward windowing concept in StreamInsight. A hopping window is defined by its length, and the offset from one window to the next. They are aligned with some absolute point on the timeline (which can also be given as a parameter to the window) and create sets of events. The diagram below shows an example of a hopping window with length of 1h and hop size (the offset) of 15 minutes, hence creating overlapping windows:   Two aspects in this diagram are important: Since this window is overlapping, an event can fall into more than one windows. If an (interval) event spans a window boundary, its lifetime will be clipped to the window, before it is passed to the set-based operation. That’s the default and currently only available window input policy. (This should only concern you if you are using a time-sensitive user-defined aggregate or operator.) The set-based operation will be applied to each of these sets, yielding a result. This result is: A single scalar value in case of built-in or user-defined aggregates. A subset of the input payloads, in case of the TopK operator. Arbitrary events, when using a user-defined operator. The timestamps of the result are almost always the ones of the windows. Only the user-defined  operator can create new events with timestamps. (However, even these event lifetimes are subject to the window’s output policy, which is currently always to clip to the window end.) Let’s assume we were calculating the sum over some payload field: var result = from window in source.HoppingWindow( TimeSpan.FromHours(1), TimeSpan.FromMinutes(15), HoppingWindowOutputPolicy.ClipToWindowEnd) select new { avg = window.Avg(e => e.Value) }; Now each window is reflected by one result event:   As you can see, the window definition defines the output frequency. No matter how many or few events we got from the input, this hopping window will produce one result every 15 minutes – except for those windows that do not contain any events at all, because StreamInsight window operations are empty-preserving (more about that another time). The “forced” output for every window can become a performance issue if you have a real-time query with many events in a wide group & apply – let me explain: imagine you have a lot of events that you group by and then aggregate within each group – classical streaming pattern. The hopping window produces a result in each group at exactly the same point in time for all groups, since the window boundaries are aligned with the timeline, not with the event timestamps. This means that the query output will become very bursty, delivering the results of all the groups at the same point in time. This becomes especially obvious if the events are long-lasting, spanning multiple windows each, so that the produced result events do not change their value very often. In such a case, a snapshot window can remedy. Snapshot windows are more difficult to explain than hopping windows: they represent those periods in time, when no event changes occur. In other words, if you mark all event start and and times on your timeline, then you are looking at all snapshot window boundaries:   If your events are never overlapping, the snapshot window will not make much sense. It is commonly used together with timestamp modification, which make it a very powerful tool. Or as Allan Mitchell expressed in in a recent tweet: “I used to look at SnapshotWindow() with disdain. Now she is my mistress, the one I turn to in times of trouble and need”. Let’s look at a simple example: I want to compute the average of some value in my events over the last minute. I don’t want this output be produced at fixed intervals, but at soon as it changes (that’s the true event-driven spirit!). The snapshot window will include all currently active event at each point in time, hence we need to extend our original events’ lifetimes into the future: Applying the Snapshot window on these events, it will appear to be “looking back into the past”: If you look at the result produced in this diagram, you can easily prove that, at each point in time, the current event value represents the average of all original input event within the last minute. Here is the LINQ representation of that query, applying the lifetime extension before the snapshot window: var result = from window in source .AlterEventDuration(e => TimeSpan.FromMinutes(1)) .SnapshotWindow(SnapshotWindowOutputPolicy.Clip) select new { avg = window.Avg(e => e.Value) }; With more complex modifications of the event lifetimes you can achieve many more query patterns. For instance “running totals” by keeping the event start times, but snapping their end times to some fixed time, like the end of the day. Each snapshot then “sees” all events that have happened in the respective time period so far. Regards, The StreamInsight Team

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• Joining on NULLs

  - by Dave Ballantyne

  A problem I see on a fairly regular basis is that of dealing with NULL values.  Specifically here, where we are joining two tables on two columns, one of which is ‘optional’ ie is nullable.  So something like this: i.e. Lookup where all the columns are equal, even when NULL.   NULL’s are a tricky thing to initially wrap your mind around.  Statements like “NULL is not equal to NULL and neither is it not not equal to NULL, it’s NULL” can cause a serious brain freeze and leave you a gibbering wreck and needing your mummy. Before we plod on, time to setup some data to demo against. Create table #SourceTable ( Id integer not null, SubId integer null, AnotherCol char(255) not null ) go create unique clustered index idxSourceTable on #SourceTable(id,subID) go with cteNums as ( select top(1000) number from master..spt_values where type ='P' ) insert into #SourceTable select Num1.number,nullif(Num2.number,0),'SomeJunk' from cteNums num1 cross join cteNums num2 go Create table #LookupTable ( Id integer not null, SubID integer null ) go insert into #LookupTable Select top(100) id,subid from #SourceTable where subid is not null order by newid() go insert into #LookupTable Select top(3) id,subid from #SourceTable where subid is null order by newid() If that has run correctly, you will have 1 million rows in #SourceTable and 103 rows in #LookupTable.  We now want to join one to the other. First attempt – Lets just join select * from #SourceTable join #LookupTable on #LookupTable.id = #SourceTable.id and #LookupTable.SubID = #SourceTable.SubID OK, that’s a fail.  We had 100 rows back,  we didn’t correctly account for the 3 rows that have null values.  Remember NULL <> NULL and the join clause specifies SUBID=SUBID, which for those rows is not true. Second attempt – Lets deal with those pesky NULLS select * from #SourceTable join #LookupTable on #LookupTable.id = #SourceTable.id and isnull(#LookupTable.SubID,0) = isnull(#SourceTable.SubID,0) OK, that’s the right result, well done and 99.9% of the time that is where its left. It is a relatively trivial CPU overhead to wrap ISNULL around both columns and compare that result, so no problems.  But, although that’s true, this a relational database we are using here, not a procedural language.  SQL is a declarative language, we are making a request to the engine to get the results we want.  How we ask for them can make a ton of difference. Lets look at the plan for our second attempt, specifically the clustered index seek on the #SourceTable   There are 2 predicates. The ‘seek predicate’ and ‘predicate’.  The ‘seek predicate’ describes how SQLServer has been able to use an Index.  Here, it has been able to navigate the index to resolve where ID=ID.  So far so good, but what about the ‘predicate’ (aka residual probe) ? This is a row-by-row operation.  For each row found in the index matching the Seek Predicate, the leaf level nodes have been scanned and tested using this logical condition.  In this example [Expr1007] is the result of the IsNull operation on #LookupTable and that is tested for equality with the IsNull operation on #SourceTable.  This residual probe is quite a high overhead, if we can express our statement slightly differently to take full advantage of the index and make the test part of the ‘Seek Predicate’. Third attempt – X is null and Y is null So, lets state the query in a slightly manner: select * from #SourceTable join #LookupTable on #LookupTable.id = #SourceTable.id and ( #LookupTable.SubID = #SourceTable.SubID or (#LookupTable.SubID is null and #SourceTable.SubId is null) ) So its slightly wordier and may not be as clear in its intent to the human reader, that is what comments are for, but the key point is that it is now clearer to the query optimizer what our intention is. Let look at the plan for that query, again specifically the index seek operation on #SourceTable No ‘predicate’, just a ‘Seek Predicate’ against the index to resolve both ID and SubID.  A subtle difference that can be easily overlooked.  But has it made a difference to the performance ? Well, yes , a perhaps surprisingly high one. Clever query optimizer well done. If you are using a scalar function on a column, you a pretty much guaranteeing that a residual probe will be used.  By re-wording the query you may well be able to avoid this and use the index completely to resolve lookups. In-terms of performance and scalability your system will be in a much better position if you can.

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• C++ strongly typed typedef

  - by Kian

  I've been trying to think of a way of declaring strongly typed typedefs, to catch a certain class of bugs in the compilation stage. It's often the case that I'll typedef an int into several types of ids, or a vector to position or velocity: typedef int EntityID; typedef int ModelID; typedef Vector3 Position; typedef Vector3 Velocity; This can make the intent of code more clear, but after a long night of coding one might make silly mistakes like comparing different kinds of ids, or adding a position to a velocity perhaps. EntityID eID; ModelID mID; if ( eID == mID ) // <- Compiler sees nothing wrong { /*bug*/ } Position p; Velocity v; Position newP = p + v; // bug, meant p + v*s but compiler sees nothing wrong Unfortunately, suggestions I've found for strongly typed typedefs include using boost, which at least for me isn't a possibility (I do have c++11 at least). So after a bit of thinking, I came upon this idea, and wanted to run it by someone. First, you declare the base type as a template. The template parameter isn't used for anything in the definition, however: template < typename T > class IDType { unsigned int m_id; public: IDType( unsigned int const& i_id ): m_id {i_id} {}; friend bool operator==<T>( IDType<T> const& i_lhs, IDType<T> const& i_rhs ); }; Friend functions actually need to be forward declared before the class definition, which requires a forward declaration of the template class. We then define all the members for the base type, just remembering that it's a template class. Finally, when we want to use it, we typedef it as: class EntityT; typedef IDType<EntityT> EntityID; class ModelT; typedef IDType<ModelT> ModelID; The types are now entirely separate. Functions that take an EntityID will throw a compiler error if you try to feed them a ModelID instead, for example. Aside from having to declare the base types as templates, with the issues that entails, it's also fairly compact. I was hoping anyone had comments or critiques about this idea? One issue that came to mind while writing this, in the case of positions and velocities for example, would be that I can't convert between types as freely as before. Where before multiplying a vector by a scalar would give another vector, so I could do: typedef float Time; typedef Vector3 Position; typedef Vector3 Velocity; Time t = 1.0f; Position p = { 0.0f }; Velocity v = { 1.0f, 0.0f, 0.0f }; Position newP = p + v*t; With my strongly typed typedef I'd have to tell the compiler that multypling a Velocity by a Time results in a Position. class TimeT; typedef Float<TimeT> Time; class PositionT; typedef Vector3<PositionT> Position; class VelocityT; typedef Vector3<VelocityT> Velocity; Time t = 1.0f; Position p = { 0.0f }; Velocity v = { 1.0f, 0.0f, 0.0f }; Position newP = p + v*t; // Compiler error To solve this, I think I'd have to specialize every conversion explicitly, which can be kind of a bother. On the other hand, this limitation can help prevent other kinds of errors (say, multiplying a Velocity by a Distance, perhaps, which wouldn't make sense in this domain). So I'm torn, and wondering if people have any opinions on my original issue, or my approach to solving it.

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• SQL SERVER – Weekly Series – Memory Lane – #051

  - 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 Explanation and Understanding NOT NULL Constraint NOT NULL is integrity CONSTRAINT. It does not allow creating of the row where column contains NULL value. Most discussed questions about NULL is what is NULL? I will not go in depth analysis it. Simply put NULL is unknown or missing data. When NULL is present in database columns, it can affect the integrity of the database. I really do not prefer NULL in the database unless they are absolutely necessary. Three T-SQL Script to Create Primary Keys on Table I have always enjoyed writing about three topics Constraint and Keys, Backup and Restore and Datetime Functions. Primary Keys constraints prevent duplicate values for columns and provides a unique identifier to each column, as well it creates clustered index on the columns. 2008 Get Numeric Value From Alpha Numeric String – UDF for Get Numeric Numbers Only SQL is great with String operations. Many times, I use T-SQL to do my string operation. Let us see User Defined Function, which I wrote a few days ago, which will return only Numeric values from Alpha Numeric values. Introduction and Example of UNION and UNION ALL It is very much interesting when I get requests from blog reader to re-write my previous articles. I have received few requests to rewrite my article SQL SERVER – Union vs. Union All – Which is better for performance? with examples. I request you to read my previous article first to understand what is the concept and read this article to understand the same concept with an example. Downgrade Database for Previous Version The main questions is how they can downgrade the from SQL Server 2005 to SQL Server 2000? The answer is : Not Possible. Get Common Records From Two Tables Without Using Join Following is my scenario, Suppose Table 1 and Table 2 has same column e.g. Column1 Following is the query, 1. Select column1,column2 From Table1 2. Select column1 From Table2 I want to find common records from these tables, but I don’t want to use the Join clause because for that I need to specify the column name for Join condition. Will you help me to get common records without using Join condition? I am using SQL Server 2005. Retrieve – Select Only Date Part From DateTime – Best Practice – Part 2 A year ago I wrote a post about SQL SERVER – Retrieve – Select Only Date Part From DateTime – Best Practice where I have discussed two different methods of getting the date part from datetime. Introduction to CLR – Simple Example of CLR Stored Procedure CLR is an abbreviation of Common Language Runtime. In SQL Server 2005 and later version of it database objects can be created which are created in CLR. Stored Procedures, Functions, Triggers can be coded in CLR. CLR is faster than T-SQL in many cases. CLR is mainly used to accomplish tasks which are not possible by T-SQL or can use lots of resources. The CLR can be usually implemented where there is an intense string operation, thread management or iteration methods which can be complicated for T-SQL. Implementing CLR provides more security to the Extended Stored Procedure. 2009 Comic Slow Query – SQL Joke Before Presentation After Presentation Enable Automatic Statistic Update on Database In one of the recent projects, I found out that despite putting good indexes and optimizing the query, I could not achieve an optimized performance and I still received an unoptimized response from the SQL Server. On examination, I figured out that the culprit was statistics. The database that I was trying to optimize had auto update of the statistics was disabled. Recently Executed T-SQL Query Please refer to blog post  query to recently executed T-SQL query on database. Change Collation of Database Column – T-SQL Script – Consolidating Collations – Extention Script At some time in your DBA career, you may find yourself in a position when you sit back and realize that your database collations have somehow run amuck, or are faced with the ever annoying CANNOT RESOLVE COLLATION message when trying to join data of varying collation settings. 2010 Visiting Alma Mater – Delivering Session on Database Performance and Career – Nirma Institute of Technology Everyone always dreams of visiting their school and college, where they have studied once. It is a great feeling to see the college once again – where you have spent the wonderful golden years of your time. College time is filled with studies, education, emotions and several plans to build a future. I consider myself fortunate as I got the opportunity to study at some of the best places in the world. Change Column DataTypes There are times when I feel like writing that I am a day older in SQL Server. In fact, there are many who are looking for a solution that is simple enough. Have you ever searched online for something very simple. I often do and enjoy doing things which are straight forward and easy to change. 2011 Three DMVs – sys.dm_server_memory_dumps – sys.dm_server_services – sys.dm_server_registry In this blog post we will see three new DMVs which are introduced in Denali. The DMVs are very simple and there is not much to describe them. So here is the simple game. I will be asking a question back to you after seeing the result of the each of the DMV and you help me to complete this blog post. A Simple Quiz – T-SQL Brain Trick If you have some time, I strongly suggest you try this quiz out as it is for sure twists your brain. 2012 List All The Column With Specific Data Types in Database 5 years ago I wrote script SQL SERVER – 2005 – List All The Column With Specific Data Types, when I read it again, it is very much relevant and I liked it. This is one of the script which every developer would like to keep it handy. I have upgraded the script bit more. I have included few additional information which I believe I should have added from the beginning. It is difficult to visualize the final script when we are writing it first time. Find First Non-Numeric Character from String The function PATINDEX exists for quite a long time in SQL Server but I hardly see it being used. Well, at least I use it and I am comfortable using it. Here is a simple script which I use when I have to identify first non-numeric character. Finding Different ColumnName From Almost Identitical Tables Well here is the interesting example of how we can use sys.column catalogue views and get the details of the newly added column. I have previously written about EXCEPT over here which is very similar to MINUS of Oracle. Storing Data and Files in Cloud – Dropbox – Personal Technology Tip I thought long and hard about doing a Personal Technology Tips series for this blog.  I have so many tips I’d like to share.  I am on my computer almost all day, every day, so I have a treasure trove of interesting tidbits I like to share if given the chance.  The only thing holding me back – which tip to share first?  The first tip obviously has the weight of seeming like the most important.  But this would mean choosing amongst my favorite tricks and shortcuts.  This is a hard task. 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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• T-SQL Tuesday #31 - Logging Tricks with CONTEXT_INFO

  - by Most Valuable Yak (Rob Volk)

  This month's T-SQL Tuesday is being hosted by Aaron Nelson [b | t], fellow Atlantan (the city in Georgia, not the famous sunken city, or the resort in the Bahamas) and covers the topic of logging (the recording of information, not the harvesting of trees) and maintains the fine T-SQL Tuesday tradition begun by Adam Machanic [b | t] (the SQL Server guru, not the guy who fixes cars, check the spelling again, there will be a quiz later). This is a trick I learned from Fernando Guerrero [b | t] waaaaaay back during the PASS Summit 2004 in sunny, hurricane-infested Orlando, during his session on Secret SQL Server (not sure if that's the correct title, and I haven't used parentheses in this paragraph yet).  CONTEXT_INFO is a neat little feature that's existed since SQL Server 2000 and perhaps even earlier.  It lets you assign data to the current session/connection, and maintains that data until you disconnect or change it.  In addition to the CONTEXT_INFO() function, you can also query the context_info column in sys.dm_exec_sessions, or even sysprocesses if you're still running SQL Server 2000, if you need to see it for another session. While you're limited to 128 bytes, one big advantage that CONTEXT_INFO has is that it's independent of any transactions.  If you've ever logged to a table in a transaction and then lost messages when it rolled back, you can understand how aggravating it can be.  CONTEXT_INFO also survives across multiple SQL batches (GO separators) in the same connection, so for those of you who were going to suggest "just log to a table variable, they don't get rolled back":  HA-HA, I GOT YOU!  Since GO starts a new batch all variable declarations are lost. Here's a simple example I recently used at work.  I had to test database mirroring configurations for disaster recovery scenarios and measure the network throughput.  I also needed to log how long it took for the script to run and include the mirror settings for the database in question.  I decided to use AdventureWorks as my database model, and Adam Machanic's Big Adventure script to provide a fairly large workload that's repeatable and easily scalable.  My test would consist of several copies of AdventureWorks running the Big Adventure script while I mirrored the databases (or not). Since Adam's script contains several batches, I decided CONTEXT_INFO would have to be used.  As it turns out, I only needed to grab the start time at the beginning, I could get the rest of the data at the end of the process.   The code is pretty small: declare @time binary(128)=cast(getdate() as binary(8)) set context_info @time   ... rest of Big Adventure code ...   go use master; insert mirror_test(server,role,partner,db,state,safety,start,duration) select @@servername, mirroring_role_desc, mirroring_partner_instance, db_name(database_id), mirroring_state_desc, mirroring_safety_level_desc, cast(cast(context_info() as binary(8)) as datetime), datediff(s,cast(cast(context_info() as binary(8)) as datetime),getdate()) from sys.database_mirroring where db_name(database_id) like 'Adv%';   I declared @time as a binary(128) since CONTEXT_INFO is defined that way.  I couldn't convert GETDATE() to binary(128) as it would pad the first 120 bytes as 0x00.  To keep the CAST functions simple and avoid using SUBSTRING, I decided to CAST GETDATE() as binary(8) and let SQL Server do the implicit conversion.  It's not the safest way perhaps, but it works on my machine. :) As I mentioned earlier, you can query system views for sessions and get their CONTEXT_INFO.  With a little boilerplate code this can be used to monitor long-running procedures, in case you need to kill a process, or are just curious  how long certain parts take.  In this example, I added code to Adam's Big Adventure script to set CONTEXT_INFO messages at strategic places I want to monitor.  (His code is in UPPERCASE as it was in the original, mine is all lowercase): declare @msg binary(128) set @msg=cast('Altering bigProduct.ProductID' as binary(128)) set context_info @msg go ALTER TABLE bigProduct ALTER COLUMN ProductID INT NOT NULL GO set context_info 0x0 go declare @msg1 binary(128) set @msg1=cast('Adding pk_bigProduct Constraint' as binary(128)) set context_info @msg1 go ALTER TABLE bigProduct ADD CONSTRAINT pk_bigProduct PRIMARY KEY (ProductID) GO set context_info 0x0 go declare @msg2 binary(128) set @msg2=cast('Altering bigTransactionHistory.TransactionID' as binary(128)) set context_info @msg2 go ALTER TABLE bigTransactionHistory ALTER COLUMN TransactionID INT NOT NULL GO set context_info 0x0 go declare @msg3 binary(128) set @msg3=cast('Adding pk_bigTransactionHistory Constraint' as binary(128)) set context_info @msg3 go ALTER TABLE bigTransactionHistory ADD CONSTRAINT pk_bigTransactionHistory PRIMARY KEY NONCLUSTERED(TransactionID) GO set context_info 0x0 go declare @msg4 binary(128) set @msg4=cast('Creating IX_ProductId_TransactionDate Index' as binary(128)) set context_info @msg4 go CREATE NONCLUSTERED INDEX IX_ProductId_TransactionDate ON bigTransactionHistory(ProductId,TransactionDate) INCLUDE(Quantity,ActualCost) GO set context_info 0x0   This doesn't include the entire script, only those portions that altered a table or created an index.  One annoyance is that SET CONTEXT_INFO requires a literal or variable, you can't use an expression.  And since GO starts a new batch I need to declare a variable in each one.  And of course I have to use CAST because it won't implicitly convert varchar to binary.  And even though context_info is a nullable column, you can't SET CONTEXT_INFO NULL, so I have to use SET CONTEXT_INFO 0x0 to clear the message after the statement completes.  And if you're thinking of turning this into a UDF, you can't, although a stored procedure would work. So what does all this aggravation get you?  As the code runs, if I want to see which stage the session is at, I can run the following (assuming SPID 51 is the one I want): select CAST(context_info as varchar(128)) from sys.dm_exec_sessions where session_id=51   Since SQL Server 2005 introduced the new system and dynamic management views (DMVs) there's not as much need for tagging a session with these kinds of messages.  You can get the session start time and currently executing statement from them, and neatly presented if you use Adam's sp_whoisactive utility (and you absolutely should be using it).  Of course you can always use xp_cmdshell, a CLR function, or some other tricks to log information outside of a SQL transaction.  All the same, I've used this trick to monitor long-running reports at a previous job, and I still think CONTEXT_INFO is a great feature, especially if you're still using SQL Server 2000 or want to supplement your instrumentation.  If you'd like an exercise, consider adding the system time to the messages in the last example, and an automated job to query and parse it from the system tables.  That would let you track how long each statement ran without having to run Profiler. #TSQL2sDay

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• T-SQL Tuesday #31 - Logging Tricks with CONTEXT_INFO

  - by Most Valuable Yak (Rob Volk)

  This month's T-SQL Tuesday is being hosted by Aaron Nelson [b | t], fellow Atlantan (the city in Georgia, not the famous sunken city, or the resort in the Bahamas) and covers the topic of logging (the recording of information, not the harvesting of trees) and maintains the fine T-SQL Tuesday tradition begun by Adam Machanic [b | t] (the SQL Server guru, not the guy who fixes cars, check the spelling again, there will be a quiz later). This is a trick I learned from Fernando Guerrero [b | t] waaaaaay back during the PASS Summit 2004 in sunny, hurricane-infested Orlando, during his session on Secret SQL Server (not sure if that's the correct title, and I haven't used parentheses in this paragraph yet).  CONTEXT_INFO is a neat little feature that's existed since SQL Server 2000 and perhaps even earlier.  It lets you assign data to the current session/connection, and maintains that data until you disconnect or change it.  In addition to the CONTEXT_INFO() function, you can also query the context_info column in sys.dm_exec_sessions, or even sysprocesses if you're still running SQL Server 2000, if you need to see it for another session. While you're limited to 128 bytes, one big advantage that CONTEXT_INFO has is that it's independent of any transactions.  If you've ever logged to a table in a transaction and then lost messages when it rolled back, you can understand how aggravating it can be.  CONTEXT_INFO also survives across multiple SQL batches (GO separators) in the same connection, so for those of you who were going to suggest "just log to a table variable, they don't get rolled back":  HA-HA, I GOT YOU!  Since GO starts a new batch all variable declarations are lost. Here's a simple example I recently used at work.  I had to test database mirroring configurations for disaster recovery scenarios and measure the network throughput.  I also needed to log how long it took for the script to run and include the mirror settings for the database in question.  I decided to use AdventureWorks as my database model, and Adam Machanic's Big Adventure script to provide a fairly large workload that's repeatable and easily scalable.  My test would consist of several copies of AdventureWorks running the Big Adventure script while I mirrored the databases (or not). Since Adam's script contains several batches, I decided CONTEXT_INFO would have to be used.  As it turns out, I only needed to grab the start time at the beginning, I could get the rest of the data at the end of the process.   The code is pretty small: declare @time binary(128)=cast(getdate() as binary(8)) set context_info @time   ... rest of Big Adventure code ...   go use master; insert mirror_test(server,role,partner,db,state,safety,start,duration) select @@servername, mirroring_role_desc, mirroring_partner_instance, db_name(database_id), mirroring_state_desc, mirroring_safety_level_desc, cast(cast(context_info() as binary(8)) as datetime), datediff(s,cast(cast(context_info() as binary(8)) as datetime),getdate()) from sys.database_mirroring where db_name(database_id) like 'Adv%';   I declared @time as a binary(128) since CONTEXT_INFO is defined that way.  I couldn't convert GETDATE() to binary(128) as it would pad the first 120 bytes as 0x00.  To keep the CAST functions simple and avoid using SUBSTRING, I decided to CAST GETDATE() as binary(8) and let SQL Server do the implicit conversion.  It's not the safest way perhaps, but it works on my machine. :) As I mentioned earlier, you can query system views for sessions and get their CONTEXT_INFO.  With a little boilerplate code this can be used to monitor long-running procedures, in case you need to kill a process, or are just curious  how long certain parts take.  In this example, I added code to Adam's Big Adventure script to set CONTEXT_INFO messages at strategic places I want to monitor.  (His code is in UPPERCASE as it was in the original, mine is all lowercase): declare @msg binary(128) set @msg=cast('Altering bigProduct.ProductID' as binary(128)) set context_info @msg go ALTER TABLE bigProduct ALTER COLUMN ProductID INT NOT NULL GO set context_info 0x0 go declare @msg1 binary(128) set @msg1=cast('Adding pk_bigProduct Constraint' as binary(128)) set context_info @msg1 go ALTER TABLE bigProduct ADD CONSTRAINT pk_bigProduct PRIMARY KEY (ProductID) GO set context_info 0x0 go declare @msg2 binary(128) set @msg2=cast('Altering bigTransactionHistory.TransactionID' as binary(128)) set context_info @msg2 go ALTER TABLE bigTransactionHistory ALTER COLUMN TransactionID INT NOT NULL GO set context_info 0x0 go declare @msg3 binary(128) set @msg3=cast('Adding pk_bigTransactionHistory Constraint' as binary(128)) set context_info @msg3 go ALTER TABLE bigTransactionHistory ADD CONSTRAINT pk_bigTransactionHistory PRIMARY KEY NONCLUSTERED(TransactionID) GO set context_info 0x0 go declare @msg4 binary(128) set @msg4=cast('Creating IX_ProductId_TransactionDate Index' as binary(128)) set context_info @msg4 go CREATE NONCLUSTERED INDEX IX_ProductId_TransactionDate ON bigTransactionHistory(ProductId,TransactionDate) INCLUDE(Quantity,ActualCost) GO set context_info 0x0   This doesn't include the entire script, only those portions that altered a table or created an index.  One annoyance is that SET CONTEXT_INFO requires a literal or variable, you can't use an expression.  And since GO starts a new batch I need to declare a variable in each one.  And of course I have to use CAST because it won't implicitly convert varchar to binary.  And even though context_info is a nullable column, you can't SET CONTEXT_INFO NULL, so I have to use SET CONTEXT_INFO 0x0 to clear the message after the statement completes.  And if you're thinking of turning this into a UDF, you can't, although a stored procedure would work. So what does all this aggravation get you?  As the code runs, if I want to see which stage the session is at, I can run the following (assuming SPID 51 is the one I want): select CAST(context_info as varchar(128)) from sys.dm_exec_sessions where session_id=51   Since SQL Server 2005 introduced the new system and dynamic management views (DMVs) there's not as much need for tagging a session with these kinds of messages.  You can get the session start time and currently executing statement from them, and neatly presented if you use Adam's sp_whoisactive utility (and you absolutely should be using it).  Of course you can always use xp_cmdshell, a CLR function, or some other tricks to log information outside of a SQL transaction.  All the same, I've used this trick to monitor long-running reports at a previous job, and I still think CONTEXT_INFO is a great feature, especially if you're still using SQL Server 2000 or want to supplement your instrumentation.  If you'd like an exercise, consider adding the system time to the messages in the last example, and an automated job to query and parse it from the system tables.  That would let you track how long each statement ran without having to run Profiler. #TSQL2sDay

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• When should I use Perl's AUTOLOAD?

  - by Robert S. Barnes

  In "Perl Best Practices" the very first line in the section on AUTOLOAD is: Don't use AUTOLOAD However all the cases he describes are dealing with OO or Modules. I have a stand alone script in which some command line switches control which versions of particular functions get defined. Now I know I could just take the conditionals and the evals and stick them naked at the top of my file before everything else, but I find it convenient and cleaner to put them in AUTOLOAD at the end of the file. Is this bad practice / style? If you think so why, and is there a another way to do it? As per brian's request I'm basically using this to do conditional compilation based on command line switches. I don't mind some constructive criticism. sub AUTOLOAD { our $AUTOLOAD; (my $method = $AUTOLOAD) =~ s/.*:://s; # remove package name if ($method eq 'tcpdump' && $tcpdump) { eval q( sub tcpdump { my $msg = shift; warn gf_time()." Thread ".threads->tid().": $msg\n"; } ); } elsif ($method eq 'loginfo' && $debug) { eval q( sub loginfo { my $msg = shift; $msg =~ s/$CRLF/\n/g; print gf_time()." Thread ".threads->tid().": $msg\n"; } ); } elsif ($method eq 'build_get') { if ($pipelining) { eval q( sub build_get { my $url = shift; my $base = shift; $url = "http://".$url unless $url =~ /^http/; return "GET $url HTTP/1.1${CRLF}Host: $base$CRLF$CRLF"; } ); } else { eval q( sub build_get { my $url = shift; my $base = shift; $url = "http://".$url unless $url =~ /^http/; return "GET $url HTTP/1.1${CRLF}Host: $base${CRLF}Connection: close$CRLF$CRLF"; } ); } } elsif ($method eq 'grow') { eval q{ require Convert::Scalar qw(grow); }; if ($@) { eval q( sub grow {} ); } goto &$method; } else { eval "sub $method {}"; return; } die $@ if $@; goto &$method; }

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• Vector math, finding coördinates on a planar between 2 vectors

  - by Will Kru

  I am trying to generate a 3d tube along a spline. I have the coördinates of the spline (x1,y1,z1 - x2,y2,z2 - etc) which you can see in the illustration in yellow. At those points I need to generate circles, whose vertices are to be connected at a later stadium. The circles need to be perpendicular to the 'corners' of two line segments of the spline to form a correct tube. Note that the segments are kept low for illustration purpose. [apparently I'm not allowed to post images so please view the image at this link] http://img191.imageshack.us/img191/6863/18720019.jpg I am as far as being able to calculate the vertices of each ring at each point of the spline, but they are all on the same planar ie same angled. I need them to be rotated according to their 'legs' (which A & B are to C for instance). I've been thinking this over and thought of the following: two line segments can be seen as 2 vectors (in illustration A & B) the corner (in illustraton C) is where a ring of vertices need to be calculated I need to find the planar on which all of the vertices will reside I then can use this planar (=vector?) to calculate new vectors from the center point, which is C and find their x,y,z using radius * sin and cos However, I'm really confused on the math part of this. I read about the dot product but that returns a scalar which I don't know how to apply in this case. Can someone point me into the right direction? [edit] To give a bit more info on the situation: I need to construct a buffer of floats, which -in groups of 3- describe vertex positions and will be connected by OpenGL ES, given another buffer with indices to form polygons. To give shape to the tube, I first created an array of floats, which -in groups of 3- describe control points in 3d space. Then along with a variable for segment density, I pass these control points to a function that uses these control points to create a CatmullRom spline and returns this in the form of another array of floats which -again in groups of 3- describe vertices of the catmull rom spline. On each of these vertices, I want to create a ring of vertices which also can differ in density (amount of smoothness / vertices per ring). All former vertices (control points and those that describe the catmull rom spline) are discarded. Only the vertices that form the tube rings will be passed to OpenGL, which in turn will connect those to form the final tube. I am as far as being able to create the catmullrom spline, and create rings at the position of its vertices, however, they are all on a planars that are in the same angle, instead of following the splines path. [/edit] Thanks!

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• Using array as map value: Cant see the error

  - by Tom

  Hi all, Im trying to create a map, where the key is an int, and the value is an array int red[3] = {1,0,0}; int green[3] = {0,1,0}; int blue[3] = {0,0,1}; std::map<int, int[3]> colours; colours.insert(std::pair<int,int[3]>(GLUT_LEFT_BUTTON,red)); //THIS IS LINE 24 ! colours.insert(std::pair<int,int[3]>(GLUT_MIDDLE_BUTTON,blue)); colours.insert(std::pair<int,int[3]>(GLUT_RIGHT_BUTTON,green)); However, when I try to compile this code, I get the following error. g++ (Ubuntu 4.4.1-4ubuntu8) 4.4.1 In file included from /usr/include/c++/4.4/bits/stl_algobase.h:66, from /usr/include/c++/4.4/bits/stl_tree.h:62, from /usr/include/c++/4.4/map:60, from ../src/utils.cpp:9: /usr/include/c++/4.4/bits/stl_pair.h: In constructor ‘std::pair<_T1, _T2>::pair(const _T1&, const _T2&) [with _T1 = int, _T2 = int [3]]’: ../src/utils.cpp:24: instantiated from here /usr/include/c++/4.4/bits/stl_pair.h:84: error: array used as initializer /usr/include/c++/4.4/bits/stl_pair.h: In constructor ‘std::pair<_T1, _T2>::pair(const std::pair<_U1, _U2>&) [with _U1 = int, _U2 = int [3], _T1 = const int, _T2 = int [3]]’: ../src/utils.cpp:24: instantiated from here /usr/include/c++/4.4/bits/stl_pair.h:101: error: array used as initializer In file included from /usr/include/c++/4.4/map:61, from ../src/utils.cpp:9: /usr/include/c++/4.4/bits/stl_map.h: In member function ‘_Tp& std::map<_Key, _Tp, _Compare, _Alloc>::operator[](const _Key&) [with _Key = int, _Tp = int [3], _Compare = std::less<int>, _Alloc = std::allocator<std::pair<const int, int [3]> >]’: ../src/utils.cpp:30: instantiated from here /usr/include/c++/4.4/bits/stl_map.h:450: error: conversion from ‘int’ to non-scalar type ‘int [3]’ requested make: *** [src/utils.o] Error 1 I really cant see where the error is. Or even if there's an error. Any help (please include an explanation to help me avoid this mistake) will be appreciated. Thanks in advance.

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• Crash in OS X Core Data Utility Tutorial

  - by vinogradov

  I'm trying to follow Apple's Core Data utility Tutorial. It was all going nicely, until... The tutorial uses a custom sub-class of NSManagedObject, called 'Run'. Run.h looks like this: #import <Foundation/Foundation.h> #import <CoreData/CoreData.h> @interface Run : NSManagedObject { NSInteger processID; } @property (retain) NSDate *date; @property (retain) NSDate *primitiveDate; @property NSInteger processID; @end Now, in Run.m we have an accessor method for the processID variable: - (void)setProcessID:(int)newProcessID { [self willChangeValueForKey:@"processID"]; processID = newProcessID; [self didChangeValueForKey:@"processID"]; } In main.m, we use functions to set up a managed object model and context, instantiate an entity called run, and add it to the context. We then get the current NSprocessInfo, in preparation for setting the processID of the run object. NSManagedObjectContext *moc = managedObjectContext(); NSEntityDescription *runEntity = [[mom entitiesByName] objectForKey:@"Run"]; Run *run = [[Run alloc] initWithEntity:runEntity insertIntoManagedObjectContext:moc]; NSProcessInfo *processInfo = [NSProcessInfo processInfo]; Next, we try to call the accessor method defined in Run.m to set the value of processID: [run setProcessID:[processInfo processIdentifier]]; And that's where it's crashing. The object run seems to exist (I can see it in the debugger), so I don't think I'm messaging nil; on the other hand, it doesn't look like the setProcessID: message is actually being received. I'm obviously still learning this stuff (that's what tutorials are for, right?), and I'm probably doing something really stupid. However, any help or suggestions would be gratefully received! ===MORE INFORMATION=== Following up on Jeremy's suggestions: The processID attribute in the model is set up like this: NSAttributeDescription *idAttribute = [[NSAttributeDescription alloc]init]; [idAttribute setName:@"processID"]; [idAttribute setAttributeType:NSInteger32AttributeType]; [idAttribute setOptional:NO]; [idAttribute setDefaultValue:[NSNumber numberWithInteger:-1]]; which seems a little odd; we are defining it as a scalar type, and then giving it an NSNumber object as its default value. In the associated class, Run, processID is defined as an NSInteger. Still, this should be OK - it's all copied directly from the tutorial. It seems to me that the problem is probably in there somewhere. By the way, the getter method for processID is defined like this: - (int)processID { [self willAccessValueForKey:@"processID"]; NSInteger pid = processID; [self didAccessValueForKey:@"processID"]; return pid; } and this method works fine; it accesses and unpacks the default int value of processID (-1). Thanks for the help so far!

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• conflicting declaration when filling a static std::map class member variable

  - by Max

  I have a class with a static std::map member variable that maps chars to a custom type Terrain. I'm attempting to fill this map in the class's implementation file, but I get several errors. Here's my header file: #ifndef LEVEL_HPP #define LEVEL_HPP #include <bitset> #include <list> #include <map> #include <string> #include <vector> #include "libtcod.hpp" namespace yarl { namespace level { class Terrain { // Member Variables private: std::bitset<5> flags; // Member Functions public: explicit Terrain(const std::string& flg) : flags(flg) {} (...) }; class Level { private: static std::map<char, Terrain> terrainTypes; (...) }; } } #endif and here's my implementation file: #include <bitset> #include <list> #include <map> #include <string> #include <vector> #include "Level.hpp" #include "libtcod.hpp" using namespace std; namespace yarl { namespace level { /* fill Level::terrainTypes */ map<char,Terrain> Level::terrainTypes['.'] = Terrain("00001"); // clear map<char,Terrain> Level::terrainTypes[','] = Terrain("00001"); // clear map<char,Terrain> Level::terrainTypes['\''] = Terrain("00001"); // clear map<char,Terrain> Level::terrainTypes['`'] = Terrain("00001"); // clear map<char,Terrain> Level::terrainTypes[178] = Terrain("11111"); // wall (...) } } I'm using g++, and the errors I get are src/Level.cpp:15: error: conflicting declaration ‘std::map, std::allocator yarl::level::Level::terrainTypes [46]’ src/Level.hpp:104: error: ‘yarl::level::Level::terrainTypes’ has a previous declaration as ‘std::map, std::allocator yarl::level::Level::terrainTypes’ src/Level.cpp:15: error: declaration of ‘std::map, std::allocator yarl::level::Level::terrainTypes’ outside of class is not definition src/Level.cpp:15: error: conversion from ‘yarl::level::Terrain’ to non-scalar type ‘std::map, std::allocator ’ requested src/Level.cpp:15: error: ‘yarl::level::Level::terrainTypes’ cannot be initialized by a non-constant expression when being declared I get a set of these for each map assignment line in the implementation file. Anyone see what I'm doing wrong? Thanks for your help.

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• help merging perl code routines together for file processing

  - by jdamae

  I need some perl help in putting these (2) processes/code to work together. I was able to get them working individually to test, but I need help bringing them together especially with using the loop constructs. I'm not sure if I should go with foreach..anyways the code is below. Also, any best practices would be great too as I'm learning this language. Thanks for your help. Here's the process flow I am looking for: -read a directory -look for a particular file -use the file name to strip out some key information to create a newly processed file -process the input file -create the newly processed file for each input file read (if i read in 10, I create 10 new files) Sample Recs: col1,col2,col3,col4,col5 [email protected],[email protected],8,2009-09-24 21:00:46,1 [email protected],[email protected],16,2007-08-18 22:53:12,33 [email protected],[email protected],16,2007-08-18 23:41:23,33 Here's my test code: Target Filetype: `/backups/test/foo101.name.aue-foo_p002.20110124.csv` Part 1: my $target_dir = "/backups/test/"; opendir my $dh, $target_dir or die "can't opendir $target_dir: $!"; while (defined(my $file = readdir($dh))) { next if ($file =~ /^\.+$/); #Get filename attributes if ($file =~ /^foo(\d{3})\.name\.(\w{3})-foo_p(\d{1,4})\.\d+.csv$/) { print "$1\n"; print "$2\n"; print "$3\n"; } print "$file\n"; } Part 2: use strict; use Digest::MD5 qw(md5_hex); #Create new file open (NEWFILE, ">/backups/processed/foo$1.name.$2-foo_p$3.out") || die "cannot create file"; my $data = ''; my $line1 = <>; chomp $line1; my @heading = split /,/, $line1; my ($sep1, $sep2, $eorec) = ( "^A", "^E", "^D"); while (<>) { my $digest = md5_hex($data); chomp; my (@values) = split /,/; my $extra = "__mykey__$sep1$digest$sep2" ; $extra .= "$heading[$_]$sep1$values[$_]$sep2" for (0..scalar(@values)); $data .= "$extra$eorec"; print NEWFILE "$data"; } #print $data; close (NEWFILE);

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• Using Constants in Perl

  - by David W.

  I am trying to define constants in Perl using the use Constant pragma: use Constant { FOO => "bar", BAR => "foo" }; I'm running into a bit of trouble, and hoping there's a standard way of handling it. First of all... I am defining a hook script for Subversion. To make things simple, I want to have a single file where the class (package) I'm using is in the same file as my actual script. Most of this package will have constants involved in it: print "This is my program"; package "MyClass"; use constant { FOO => "bar" }; sub new { yaddah, yaddah, yaddah. I would like my constant FOO to be accessible to my main program. I would like to do this without having to refer to it as MyClass::FOO. Normally, when the package is a separate file, I could do this in my main program: use MyClass qw(FOO); but, since my class and program are a single file, I can't do that. What would be the best way for my main program to be able to access my constants defined in my class? The second issue... I would like to use the constant values as hash keys: $myHash{FOO} = "bar"; The problem is that %myHash has the literal string FOO as the key and not the value of the constant. This causes problems when I do things like this: if (defined($myHash{FOO})) { print "Key " . FOO . " does exist!\n"; } I could force the context: if (defined("" . FOO . "")) { I could add parentheses: if (defined(FOO())) { Or, I could use a temporary variable: my $foo = FOO; if (defined($foo)) { None of these are really nice ways of handling this issue. So, what is the best way? Is there one way I'm missing? By the way, I don't want to use Readonly::Scalar because it is 1). slow, and 2). not part of the standard Perl package. I want to define my hook not to require additional Perl packages and to be as simple as possible to work.

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• Loading the last related record instantly for multiple parent records using Entity framework

  - by Guillaume Schuermans

  Does anyone know a good approach using Entity Framework for the problem described below? I am trying for our next release to come up with a performant way to show the placed orders for the logged on customer. Of course paging is always a good technique to use when a lot of data is available I would like to see an answer without any paging techniques. Here's the story: a customer places an order which gets an orderstatus = PENDING. Depending on some strategy we move that order up the chain in order to get it APPROVED. Every change of status is logged so we can see a trace for statusses and maybe even an extra line of comment per status which can provide some extra valuable information to whoever sees this order in an interface. So an Order is linked to a Customer. One order can have multiple orderstatusses stored in OrderStatusHistory. In my testscenario I am using a customer which has 100+ Orders each with about 5 records in the OrderStatusHistory-table. I would for now like to see all orders in one page not using paging where for each Order I show the last relevant Status and the extra comment (if there is any for this last status; both fields coming from OrderStatusHistory; the record with the highest Id for the given OrderId). There are multiple scenarios I have tried, but I would like to see any potential other solutions or comments on the things I have already tried. Trying to do Include() when getting Orders but this still results in multiple queries launched on the database. Each order triggers an extra query to the database to get all orderstatusses in the history table. So all statusses are queried here instead of just returning the last relevant one, plus 100 extra queries are launched for 100 orders. You can imagine the problem when there are 100000+ orders in the database. Having 2 computed columns on the database: LastStatus, LastStatusInformation and a regular Linq-Query which gets those columns which are available through the Entity-model. The problem with this approach is the fact that those computed columns are determined using a scalar function which can not be changed without removing the formula from the computed column, etc... In the end I am very familiar with SQL and Stored procedures, but since the rest of the data-layer uses Entity Framework I would like to stick to it as long as possible, even though I have my doubts about performance. Using the SQL approach I would write something like this: WITH cte (RN, OrderId, [Status], Information) AS ( SELECT ROW_NUMBER() OVER (PARTITION BY OrderId ORDER BY Id DESC), OrderId, [Status], Information FROM OrderStatus ) SELECT o.Id, cte.[Status], cte.Information AS StatusInformation, o.* FROM [Order] o INNER JOIN cte ON o.Id = cte.OrderId AND cte.RN = 1 WHERE CustomerId = @CustomerId ORDER BY 1 DESC; which returns all orders for the customer with the statusinformation provided by the Common Table Expression. Does anyone know a good approach using Entity Framework?

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• Why is this statement treated as a string instead of its result?

  - by reve_etrange

  I am trying to perform some composition-based filtering on a large collection of strings (protein sequences). I wrote a group of three subroutines in order to take care of it, but I'm running into trouble in two ways - one minor, one major. The minor trouble is that when I use List::MoreUtils 'pairwise' I get warnings about using $a and $b only once and them being uninitialized. But I believe I'm calling this method properly (based on CPAN's entry for it and some examples from the web). The major trouble is an error "Can't use string ("17/32") as HASH ref while "strict refs" in use..." It seems like this can only happen if the foreach loop in &comp is giving the hash values as a string instead of evaluating the division operation. I'm sure I've made a rookie mistake, but can't find the answer on the web. The first time I even looked at perl code was last Wednesday... use List::Util; use List::MoreUtils; my @alphabet = ( 'A', 'R', 'N', 'D', 'C', 'Q', 'E', 'G', 'H', 'I', 'L', 'K', 'M', 'F', 'P', 'S', 'T', 'W', 'Y', 'V' ); my $gapchr = '-'; # Takes a sequence and returns letter = occurrence count pairs as hash. sub getcounts { my %counts = (); foreach my $chr (@alphabet) { $counts{$chr} = ( $[0] =~ tr/$chr/$chr/ ); } $counts{'gap'} = ( $[0] =~ tr/$gapchr/$gapchr/ ); return %counts; } # Takes a sequence and returns letter = fractional composition pairs as a hash. sub comp { my %comp = getcounts( $[0] ); foreach my $chr (@alphabet) { $comp{$chr} = $comp{$chr} / ( length( $[0] ) - $comp{'gap'} ); } return %comp; } # Takes two sequences and returns a measure of the composition difference between them, as a scalar. # Originally all on one line but it was unreadable. sub dcomp { my @dcomp = pairwise { $a - $b } @{ values( %{ comp( $[0] ) } ) }, @{ values( %{ comp( $[1] ) } ) }; @dcomp = apply { $_ ** 2 } @dcomp; my $dcomp = sqrt( sum( 0, @dcomp ) ) / 20; return $dcomp; } Much appreciation for any answers or advice!

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• How do I map a one-to-one value type association in an joined-subclass?

  - by David Rubin

  I've got a class hierarchy mapped using table-per-subclass, and it's been working out great: class BasicReport { ... } class SpecificReport : BasicReport { ... } With mappings: <class name="BasicReport" table="reports"> <id name="Id" column="id">...</id> <!-- some common properties --> </class> <joined-subclass name="SpecificReport" table="specificReports" extends="BasicReport"> <key column="id"/> <!-- some special properties --> </joined-subclass> So far, so good. The problem I'm struggling with is how to add a property to one of my subclasses that's both a value type for which I have an IUserType implemented and also mapped via an association: class OtherReport : BasicReport { public SpecialValue V { get; set; } } class SpecialValueUserType : IUserType { ... } What I'd like to do is: <joined-subclass name="OtherReport" table="otherReports" extends="BasicReport"> <key column="id"/> <join table="rptValues" fetch="join"> <key column="rptId"/> <property name="V" column="value" type="SpecialValueUserType"/> </join> </joined-subclass> This accurately reflects the intent, and the pre-existing database schema I'm tied to: the SpecialValue instance is a property of the OtherReport, but is stored in a separate table ("rptValues"). Unfortunately, it seems as though I can't do this, because <join> elements can't be used in <joined-subclass> mappings. <one-to-one> would require creating a class mapping for SpecialValue, which doesn't make any sense given that SpecialValue is just a meaningful scalar. So what can I do? Do I have any options? Right now I'm playing a game with sets: class OtherReport : BasicReport { public SpecialValue V { get { return _values.Count() > 0 ? _values.First() : null; } set { _values.Clear(); _values.Add(value); } } private ICollection<SpecialValue> _values; } With mapping: <joined-subclass name="OtherReport" table="otherReports" extends="BasicReport"> <key column="id"/> <set name="_values" access="field" table="rptValues" cascade="all-delete-orphan"> <key column="rptId" /> <element column="value" type="SpecialValueUserType"/> </set> </joined-subclass> Thanks in advance for the help! I've been banging my head into my desk for several days now.

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• What's the best way to handle modules that use each other?

  - by Axeman

  What's the best way to handle modules that use each other? Let's say I have a module which has functions for hashes: # Really::Useful::Functions::On::Hash.pm use base qw<Exporter>; use strict; use warnings; use Really::Useful::Functions::On::List qw<transform_list>; our @EXPORT_OK = qw<transform_hash transform_hash_as_list ...>; #... sub transform_hash { ... } #... sub transform_hash_as_list { return transform_list( %{ shift() } ); } #... 1 And another module has been segmented out for lists: # Really::Useful::Functions::On::List.pm use base qw<Exporter>; use strict; use warnings; use Really::Useful::Functions::On::Hash qw<transform_hash>; our @EXPORT_OK = qw<transform_list some_func ...>; #... sub transform_list { ... } #... sub some_func { my %params = transform_hash @_; #... } #... 1 Suppose that enough of these utility functions are handy enough that I'll want to use them in BEGIN statements and import functions to process parameter lists or configuration data. I have been putting sub definitions into BEGIN blocks to make sure they are ready to use whenever somebody includes the module. But I have gotten into hairy race conditions where a definition is not completed in a BEGIN block. I put evolving code idioms into modules so that I can reuse any idiom I find myself coding over and over again. For instance: sub list_if { my $condition = shift; return unless $condition; my $more_args = scalar @_; my $arg_list = @_ > 1 ? \@_ : @_ ? shift : $condition; if (( reftype( $arg_list ) || '' ) eq 'ARRAY' ) { return wantarray ? @$arg_list : $arg_list; } elsif ( $more_args ) { return $arg_list; } return; } captures two idioms that I'm kind of tired of typing: @{ func_I_hope_returns_a_listref() || [] } and ( $condition ? LIST : ()) The more I define functions in BEGIN blocks, the more likely I'll use these idiom bricks to express the logic the more likely that bricks are needed in BEGIN blocks. Do people have standard ways of dealing with this sort of language-idiom-brick model? I've been doing mostly Pure-Perl; will XS alleviate some of this?

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• Shuffle tiles position in the beginning of the game XNA Csharp

  - by GalneGunnar

  Im trying to create a puzzlegame where you move tiles to certain positions to make a whole image. I need help with randomizing the tiles startposition so that they don't create the whole image at the beginning. There is also something wrong with my offset, that's why it's set to (0,0). I know my code is not good, but Im just starting to learn :] Thanks in advance My Game1 class: { public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; Texture2D PictureTexture; Texture2D FrameTexture; // Offset för bildgraff Vector2 Offset = new Vector2(0,0); //skapar en array som ska hålla delar av den stora bilden Square[,] squareArray = new Square[4, 4]; // Random randomeraBilder = new Random(); //Width och Height för bilden int pictureHeight = 95; int pictureWidth = 144; Random randomera = new Random(); int index = 0; MouseState oldMouseState; int WindowHeight; int WindowWidth; public Game1() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; //scalar Window till 800x 600y graphics.PreferredBackBufferWidth = 800; graphics.PreferredBackBufferHeight = 600; graphics.ApplyChanges(); } protected override void Initialize() { IsMouseVisible = true; base.Initialize(); } protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); PictureTexture = Content.Load<Texture2D>(@"Images/bildgraff"); FrameTexture = Content.Load<Texture2D>(@"Images/framer"); //Laddar in varje liten bild av den stora bilden i en array for (int x = 0; x < 4; x++) { for (int y = 0; y < 4; y++) { Vector2 position = new Vector2(x * pictureWidth, y * pictureHeight); position = position + Offset; Rectangle square = new Rectangle(x * pictureWidth, y * pictureHeight, pictureWidth, pictureHeight); Square frame = new Square(position, PictureTexture, square, Offset, index); squareArray[x, y] = frame; index++; } } } protected override void UnloadContent() { } protected override void Update(GameTime gameTime) { if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed) this.Exit(); MouseState ms = Mouse.GetState(); if (oldMouseState.LeftButton == ButtonState.Pressed && ms.LeftButton == ButtonState.Released) { // ta reda på vilken position vi har tryckt på int col = ms.X / pictureWidth; int row = ms.Y / pictureHeight; for (int x = 0; x < squareArray.GetLength(0); x++) { for (int y = 0; y < squareArray.GetLength(1); y++) { // kollar om rutan är tom och så att indexet inte går utanför för "col" och "row" if (squareArray[x, y].index == 0 && col >= 0 && row >= 0 && col <= 3 && row <= 3) { if (squareArray[x, y].index == 0 * col) { //kollar om rutan brevid mouseclick är tom if (col > 0 && squareArray[col - 1, row].index == 0 || row > 0 && squareArray[col, row - 1].index == 0 || col < 3 && squareArray[col + 1, row].index == 0 || row < 3 && squareArray[col, row + 1].index == 0) { Square sqaure = squareArray[col, row]; Square hal = squareArray[x, y]; squareArray[x, y] = sqaure; squareArray[col, row] = hal; for (int i = 0; i < 4; i++) { for (int j = 0; j < 4; j++) { Vector2 goalPosition = new Vector2(x * pictureWidth, y * pictureHeight); squareArray[x, y].Swap(goalPosition); } } } } } } } } //if (oldMouseState.RightButton == ButtonState.Pressed && ms.RightButton == ButtonState.Released) //{ // for (int x = 0; x < 4; x++) // { // for (int y = 0; y < 4; y++) // { // } // } //} oldMouseState = ms; base.Update(gameTime); } protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); WindowHeight = Window.ClientBounds.Height; WindowWidth = Window.ClientBounds.Width; Rectangle screenPosition = new Rectangle(0,0, WindowWidth, WindowHeight); spriteBatch.Begin(); spriteBatch.Draw(FrameTexture, screenPosition, Color.White); //Ritar ut alla brickorna förutom den som har index 0 for (int x = 0; x < 4; x++) { for (int y = 0; y < 4; y++) { if (squareArray[x, y].index != 0) { squareArray[x, y].Draw(spriteBatch); } } } spriteBatch.End(); base.Draw(gameTime); } } } My square class: class Square { public Vector2 position; public Texture2D grafTexture; public Rectangle square; public Vector2 offset; public int index; public Square(Vector2 position, Texture2D grafTexture, Rectangle square, Vector2 offset, int index) { this.position = position; this.grafTexture = grafTexture; this.square = square; this.offset = offset; this.index = index; } public void Draw(SpriteBatch spritebatch) { spritebatch.Draw(grafTexture, position, square, Color.White); } public void RandomPosition() { } public void Swap(Vector2 Goal ) { if (Goal.X > position.X) { position.X = position.X + 144; } else if (Goal.X < position.X) { position.X = position.X - 144; } else if (Goal.Y < position.Y) { position.Y = position.Y - 95; } else if (Goal.Y > position.Y) { position.Y = position.Y + 95; } } } }

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