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  • Prolog - How do you distinguish between just a string, and a variable? [closed]

    - by Mr Prolog
    When you are querying a Prolog database, often you will use terms that start with an uppercase letter as your variables. However, let's say that one of the constraints on your query is that a person's location must be "Dallas", and you want to query all the information in the database who meet those specifications. How would do you correctly make sure that Dallas is not interpreted as a variable to store a value in, and is interpreted as a string instead, for usage as a constraint on the query?

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  • Better way to search for text in two columns

    - by David
    Here is the scenario. I am making a custom blogging software for my site. I am implementing a search feature. It's not very sophisticated - basically it just takes the search phrase entered and runs this query: $query="SELECT * FROM `blog` WHERE `title` LIKE '%$q%' OR `post` LIKE '%$q%'"; Which is meant to simply search the title and post body for the phrase entered. Is there a better way to do that, keeping in mind how long it would take to run the query on up to 100 rows, each with a post length of up to 1500 characters? I have considered using a LIMIT statement to (sometimes) restrict the number of rows that the query would examine. Good idea?

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  • Repository query conditions, dependencies and DRY

    - by vFragosop
    To keep it simple, let's suppose an application which has Accounts and Users. Each account may have any number of users. There's also 3 consumers of UserRepository: An admin interface which may list all users Public front-end which may list all users An account authenticated API which should only list it's own users Assuming UserRepository is something like this: class UsersRepository extends DatabaseAbstraction { private function query() { return $this->database()->select('users.*'); } public function getAll() { return $this->query()->exec(); } // IMPORTANT: // Tons of other methods for searching, filtering, // joining of other tables, ordering and such... } Keeping in mind the comment above, and the necessity to abstract user querying conditions, How should I handle querying of users filtering by account_id? I can picture three possible roads: 1. Should I create an AccountUsersRepository? class AccountUsersRepository extends UserRepository { public function __construct(Account $account) { $this->account = $account; } private function query() { return parent::query() ->where('account_id', '=', $this->account->id); } } This has the advantage of reducing the duplication of UsersRepository methods, but doesn't quite fit into anything I've read about DDD so far (I'm rookie by the way) 2. Should I put it as a method on AccountsRepository? class AccountsRepository extends DatabaseAbstraction { public function getAccountUsers(Account $account) { return $this->database() ->select('users.*') ->where('account_id', '=', $account->id) ->exec(); } } This requires the duplication of all UserRepository methods and may need another UserQuery layer, that implements those querying logic on chainable way. 3. Should I query UserRepository from within my account entity? class Account extends Entity { public function getUsers() { return UserRepository::findByAccountId($this->id); } } This feels more like an aggregate root for me, but introduces dependency of UserRepository on Account entity, which may violate a few principles. 4. Or am I missing the point completely? Maybe there's an even better solution? Footnotes: Besides permissions being a Service concern, in my understanding, they shouldn't implement SQL query but leave that to repositories since those may not even be SQL driven.

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  • Content Query Web Part - How do you OrderBy when you QueryOverride?

    - by Richard JP Le Guen
    How do you order items when you override the QueryOverride property of the Content Query Web Part? I have been given responsibility for a Web Part which extends the Content Query Web Part. The QueryOverride property of this Web Part is programmatically changed. Currently, the Web Part does not function as designed, as it does not order the items according to the appropriate field. If I add an <OrderBy> node to the QueryOverride property I get an error message along the lines of 'something wrong with the query this web part is...' and the Content Query Web Part doesn't seem to have an OrderBy property which I could use instead. The "QueryOverride property" part of this msdn article seems to suggest I should be able to add an <OrderBy> node to the QueryOverride but a number of web sites I've been reading suggest that this is not true. So, wow do you order items when you override the QueryOverride property of the Content Query Web Part?

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  • How to retrieve only updated/new records since the last query in SQL?

    - by William Choi
    Hi all, I was asked to design a class for caching SQL query results. Calling the class' query method will query and cache the entire set of results at the first time; afterward, each subsequence query will retrieve only the updated portion, and will merge the result into the cache. If the class is required to be generic, i.e. NO knowledge about the db and the tables, do you have any idea? Is it possible, and how to retrieve only updated/new records since the last query? Thanks! William

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  • How to test a lamda expression var query result is null?

    - by mike
    var query = from emp in dbEmp.Employees join dept in dbEmp.Departments on emp.DeptID equals dept.DeptID where dept.DepartmentName.Contains(this.TextBox1.Text) select new { EmpID = emp.EmpID, EmpName = emp.EmpName, Age = emp.Age, Address = emp.Address, DeptName = dept.DepartmentName }; if (query==null) Label1.Text = "no results match your search"; GridView1.DataSource = query; GridView1.DataBind(); Everything works in the right way, but the label doesn't show the message when query result returns null. The label can show without condition(querry==null). So how to test if a var query result returns nothing? Thanks

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  • Adding a calculated field to a Query at run time.

    - by JamesB
    I'm getting data using a query in Delphi, and would like to add a calculated field to the query before it runs. The calculated field is using values in code as well as the query so I can't just calculate it in SQL. I know I can attach an OnCalcFields Event to actually make the calculation, but the problem is after adding the calculated field there are no other fields in the query... I did some digging and found that all of the field defs are created but the actual fields are only created if DefaultFields then CreateFields Default Fields is specified procedure TDataSet.DoInternalOpen; begin FDefaultFields := FieldCount = 0; ... end; Which would indicate that if you add fields you only get the fields you added. I would like all the fields in the query AS WELL AS the ones I Add. Is this possible or do I have to add all the fields I'm using as well?

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  • Draw images with warped triangles on a web server [migrated]

    - by epologee
    The scenario The Flash front end of my current project produces images that a web server needs to combine into a video. Both frame-rate and frame-resolution are sizeable enough that sending an image sequence to the back end is not feasible (in both time and client bandwidth). Instead, we're trying to recreate the image drawing on the back end as well. Correct and slow, or incorrect and fast The problem is that this involves quite a bit of drawing textured triangles, and two solutions we found in Python (here and there) are so inefficient, that the drawing takes about 60 seconds per frame, resulting in a whopping 7,5 hours of processing time for a 30 second clip. Unacceptable. When using a PHP-module to send commands to ImageMagick for image manipulation, the whole process is super fast (tenths of a second per frame), but ImageMagick seems to be unable to draw triangles the way we do it in the front end, so the final results do not match. Unacceptable. What I'm asking here, is if there's someone who would know a way to solve this issue, by any means necessary that would run on a web server. Warping an image Let me explain the process of the front end: Perform a Delaunay calculation on points in an image to get an evenly distributed mesh of triangles. Offset the points/vertices in the mesh, distorting or warping the image. Draw the warped triangles on a new bitmap. We can send the results (coordinates) of steps 1 and 2 to the back end, to then draw the warped triangles and save it to an image on disk (or append as a frame to the video). But that last step is what I need help with. The Question Is there an alternative to ImageMagick that can draw triangles in a bitmap? Is there some other library, like a C library, that would allow us to do this? Or could we achieve this effect more easily by switching back end technologies, like Ruby? (.Net and Java are, unfortunately, not really options right now) Many thanks. EP. P.S. I'd appreciate re-tagging efforts, I don't quite know what labels to put on this question. Thanks!

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  • Sql Query - Limiting query results

    - by Gublooo
    I am quite certain we cannot use the LIMIT clause for what I want to do - so wanted to find if there are any other ways we can accomplish this. I have a table which captures which user visited which store. Every time a user visits a store, a row is inserted into this table. Some of the fields are shopping_id (primary key) store_id user_id Now what I want is - for a given set of stores, find the top 5 users who have visited the store max number of times. I can do this 1 store at a time as: select store_id,user_id,count(1) as visits from shopping where store_id = 60 group by user_id,store_id order by visits desc Limit 5 This will give me the 5 users who have visited store_id=60 the max times What I want to do is provide a list of 10 store_ids and for each store fetch the 5 users who have visited that store max times select store_id,user_id,count(1) as visits from shopping where store_id in (60,61,62,63,64,65,66) group by user_id,store_id order by visits desc Limit 5 This will not work as the Limit at the end will return only 5 rows rather than 5 rows for each store. Any ideas on how I can achieve this. I can always write a loop and pass 1 store at a time but wanted to know if there is a better way

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  • MDX: Problem filtering results in MDX query used in Reporting Services query

    - by wgpubs
    Why aren't my results being filtered by the members from my [Group Hierarchy] returned via the filter() statment below? SELECT NON EMPTY {[Measures].[Group Count], [Measures].[Overall Group Count] } ON COLUMNS, NON EMPTY { [Survey].[Surveys By Year].[Survey Year].ALLMEMBERS * [Response Status].[Response Status].[Response Status].ALLMEMBERS} DIMENSION PROPERTIES MEMBER_CAPTION, MEMBER_UNIQUE_NAME ON ROWS FROM ( SELECT ( { [Survey Type].[Survey Type Hierarchy].&[9] } ) ON COLUMNS FROM ( SELECT ( { [Response Status].[Response Status].[All] } ) ON COLUMNS FROM ( SELECT ( STRTOSET(@SurveySurveysByYear, CONSTRAINED) ) ON COLUMNS FROM ( SELECT(filter([Group].[Group Hierarchy].members, instr(@GroupGroupFullName,[Group].[Group Hierarchy].Properties( "Group Full Name" )))) on columns FROM [SysSurveyDW])))) CELL PROPERTIES VALUE, BACK_COLOR, FORE_COLOR, FORMATTED_VALUE, FORMAT_STRING, FONT_NAME, FONT_SIZE, FONT_FLAGS

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  • Variable in one query is getting into another query in view

    - by Jason Shultz
    I have two foreach statements. The variable from one one is somehow getting into another and i'm not sure how to fix it. Here's my controller: // Categories Page Code function categories($id) { $this->load->model('Business_model'); $data['businessList'] = $this->Business_model->categoryPageList($id); $data['catList'] = $this->Business_model->categoryList(); $data['featured'] = $this->Business_model->frontPageList(); $data['user_id'] = $this->tank_auth->get_user_id(); $data['username'] = $this->tank_auth->get_username(); $data['page_title'] = 'Welcome To Jerome - Largest Ghost Town in America'; $data['page'] = 'category_view'; // pass the actual view to use as a parameter $this->load->view('container',$data); } What happens is categories will only show the businesses in a certain category. The businesses are pulled from the database using the categoryPageList($id) function. Here is that function: function categoryPageList($id) { $this->db->select('b.id, b.busname, b.busowner, b.webaddress, p.thumb, v.title, c.catname, s.specname, p.thumb, c.id'); $this->db->from ('business AS b'); $this->db->where('b.category', $id); $this->db->join('photos AS p', 'p.busid = b.id', 'left'); $this->db->join('video AS v', 'v.busid = b.id', 'left'); $this->db->join('specials AS s', 's.busid = b.id', 'left'); $this->db->join('category As c', 'b.category = c.id', 'left'); $this->db->group_by("b.id"); return $this->db->get(); } And here is the view: <h2>Welcome to Jerome, Arizona</h2> <p>Choose the Category of Business you are interested in:<br/> <?php foreach ($catList->result() as $row): ?> <a href="/site/categories/<?=$row->id?>"><?=$row->catname?></a>, &nbsp; <?php endforeach; ?></p> <table id="businessTable" class="tablesorter"> <thead><tr><th>Business Name</th><th>Business Owner</th><th>Web</th><th>Photos</th><th>Videos</th><th>Specials</th></tr></thead> <?php if(count($businessList) > 0) : foreach ($businessList->result() as $crow): ?> <tr> <td><a href="/site/business/<?=$crow->id?>"><?=$crow->busname?></a></td> <td><?=$crow->busowner?></td> <td><a href="<?=$crow->webaddress?>">Visit Site</a></td> <td> <?php if(isset($crow->thumb)):?> yes <?php else:?> no <?php endif?> </td> <td> <?php if(isset($crow->title)):?> yes <?php else:?> no <?php endif?> </td> <td> <?php if(isset($crow->specname)):?> yes <?php else:?> no <?php endif?> </td> </tr> <?php endforeach; ?> <?php else : ?> <td colspan="4"><p>No Category Selected</p></td> <?php endif; ?> </table> The problem occurs here. <?=$crow->id?> should be showing the row id from the business table. Instead, it's showing the row ID of the category table. so, if i'm viewing /site/categories/6 <?=$crow->id?> will show 6 when it should be showing 10 (the row ID of the only business in that category at this time. How can I fix this?

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  • How do I break down MySQL query results into categories, each with a specific number of rows?

    - by Mel
    Hello, Problem: I want to list n number of games from each genre (order not important) The following MySQL query resides inside a ColdFusion function. It is meant to list all games under a platform (for example, list all PS3 games; list all Xbox 360 games; etc...). The variable for PlatformID is passed through the URL. I have 9 genres, and I would like to list 10 games from each genre. SELECT games.GameID AS GameID, games.GameReleaseDate AS rDate, titles.TitleName AS tName, titles.TitleShortDescription AS sDesc, genres.GenreName AS gName, platforms.PlatformID, platforms.PlatformName AS pName, platforms.PlatformAbbreviation AS pAbbr FROM (((games join titles on((games.TitleID = titles.TitleID))) join genres on((genres.GenreID = games.GenreID))) join platforms on((platforms.PlatformID = games.PlatformID))) WHERE (games.PlatformID = '#ARGUMENTS.PlatformID#') ORDER BY GenreName ASC, GameReleaseDate DESC Once the query results come back I group them in ColdFusion as follows: <cfoutput query="ListGames" group="gName"> (first loop which lists genres) #ListGames.gName# <cfoutput> (nested loop which lists games) #ListGames.tName# </cfoutput> </cfoutput> The problem is that I only want 10 games from each genre to be listed. If I place a "limit" of 50 in the SQL, I will get ~ 50 games of the same genre (depending on how much games of that genre there are). The second issue is I don't want the overload of querying the database for all games when each person will only look at a few. What is the correct way to do this? Many thanks!

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  • How to create a UDF that takes a query string and returns the query's resultset

    - by Martin
    I want to create a stored procedure that takes a simple SELECT statement and return the resultset as a CSV string. So the basic idea is get the sql statement from user input, run it using EXEC(@stmt) and convert the resultset to text using cursors. However, as SQLServer doesn't allow: select * from storedprocedure(@sqlStmt) UDF with EXEC(@sqlStmt) so I tried Insert into #tempTable EXEC(@sqlStmt), but this doesn't work (error = "invalid object name #tempTable"). I'm stuck. Could you please shed some light on this matter? Many thanks EDIT: Actually the output (e.g CSV string) is not important. The problem is I don't know how to assign a cursor to the resultset returned by EXEC. SP and UDF do not work with Exec() while creating a temp table before inserting values is impossible without knowing the input statement. I thought of OPENQUERY but it does not accept variables as its parameters.

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  • How do I break down MySQL query results into categories, each with a specific number of rows?

    - by Mel
    Hello, Problem: I want to list n number of games from each genre (order not important) The following MySQL query resides inside a ColdFusion function. It is meant to list all games under a platform (for example, list all PS3 games; list all Xbox 360 games; etc...). The variable for PlatformID is passed through the URL. I have 9 genres, and I would like to list 10 games from each genre. SELECT games.GameID AS GameID, games.GameReleaseDate AS rDate, titles.TitleName AS tName, titles.TitleShortDescription AS sDesc, genres.GenreName AS gName, platforms.PlatformID, platforms.PlatformName AS pName, platforms.PlatformAbbreviation AS pAbbr FROM (((games join titles on((games.TitleID = titles.TitleID))) join genres on((genres.GenreID = games.GenreID))) join platforms on((platforms.PlatformID = games.PlatformID))) WHERE (games.PlatformID = '#ARGUMENTS.PlatformID#') ORDER BY GenreName ASC, GameReleaseDate DESC Once the query results come back I group them in ColdFusion as follows: <cfoutput query="ListGames" group="gName"> (first loop which lists genres) #ListGames.gName# <cfoutput> (nested loop which lists games) #ListGames.tName# </cfoutput> </cfoutput> The problem is that I only want 10 games from each genre to be listed. If I place a "limit" of 50 in the SQL, I will get ~ 50 games of the same genre (depending on how much games of that genre there are). The second issue is I don't want the overload of querying the database for all games when each person will only look at a few. What is the correct way to do this? Many thanks!

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  • LINQ Query using UDF that receives parameters from the query

    - by Ben Fidge
    I need help using a UDF in a LINQ which calculates a users position from a fixed point. int pointX = 567, int pointY = 534; // random points on a square grid var q = from n in _context.Users join m in _context.GetUserDistance(n.posY, n.posY, pointX, pointY, n.UserId) on n.UserId equals m.UserId select new User() { PosX = n.PosX, PosY = n.PosY, Distance = m.Distance, Name = n.Name, UserId = n.UserId }; The GetUserDistance is just a UDF that returns a single row in a TVP with that users distance from the points deisgnated in pointX and pointY variables, and the designer generates the following for it: [global::System.Data.Linq.Mapping.FunctionAttribute(Name="dbo.GetUserDistance", IsComposable=true)] public IQueryable<GetUserDistanceResult> GetUserDistance([global::System.Data.Linq.Mapping.ParameterAttribute(Name="X1", DbType="Int")] System.Nullable<int> x1, [global::System.Data.Linq.Mapping.ParameterAttribute(Name="X2", DbType="Int")] System.Nullable<int> x2, [global::System.Data.Linq.Mapping.ParameterAttribute(Name="Y1", DbType="Int")] System.Nullable<int> y1, [global::System.Data.Linq.Mapping.ParameterAttribute(Name="Y2", DbType="Int")] System.Nullable<int> y2, [global::System.Data.Linq.Mapping.ParameterAttribute(Name="UserId", DbType="Int")] System.Nullable<int> userId) { return this.CreateMethodCallQuery<GetUserDistanceResult>(this, ((MethodInfo)(MethodInfo.GetCurrentMethod())), x1, x2, y1, y2, userId); } when i try to compile i get The name 'n' does not exist in the current context

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  • PHP – Slow String Manipulation

    - by Simon Roberts
    I have some very large data files and for business reasons I have to do extensive string manipulation (replacing characters and strings). This is unavoidable. The number of replacements runs into hundreds of thousands. It's taking longer than I would like. PHP is generally very quick but I'm doing so many of these string manipulations that it's slowing down and script execution is running into minutes. This is a pain because the script is run frequently. I've done some testing and found that str_replace is fastest, followed by strstr, followed by preg_replace. I've also tried individual str_replace statements as well as constructing arrays of patterns and replacements. I'm toying with the idea of isolating string manipulation operation and writing in a different language but I don't want to invest time in that option only to find that improvements are negligible. Plus, I only know Perl, PHP and COBOL so for any other language I would have to learn it first. I'm wondering how other people have approached similar problems? I have searched and I don't believe that this duplicates any existing questions.

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  • Filtering SQLAlchemy query on attribute_mapped_collection field of relationship

    - by bsa
    I have two classes, Tag and Hardware, defined with a simple parent-child relationship (see the full definition at the end). Now I want to filter a query on Tag using the version field in Hardware through an attribute_mapped_collection, eg: def get_tags(order_code=None, hardware_filters=None): session = Session() query = session.query(Tag) if order_code: query = query.filter(Tag.order_code == order_code) if hardware_filters: for k, v in hardware_filters.iteritems(): query = query.filter(getattr(Tag.hardware, k).version == v) return query.all() But I get: AttributeError: Neither 'InstrumentedAttribute' object nor 'Comparator' object associated with Tag.hardware has an attribute 'baseband The same thing happens if I strip it back by hard-coding the attribute, eg: query.filter(Tag.hardware.baseband.version == v) I can do it this way: query = query.filter(Tag.hardware.any(artefact=k, version=v)) But why can't I filter directly through the attribute? Class definitions class Tag(Base): __tablename__ = 'tag' tag_id = Column(Integer, primary_key=True) order_code = Column(String, nullable=False) version = Column(String, nullable=False) status = Column(String, nullable=False) comments = Column(String) hardware = relationship( "Hardware", backref="tag", collection_class=attribute_mapped_collection('artefact'), ) __table_args__ = ( UniqueConstraint('order_code', 'version'), ) class Hardware(Base): __tablename__ = 'hardware' hardware_id = Column(Integer, primary_key=True) tag_id = Column(String, ForeignKey('tag.tag_id')) product_id = Column(String, nullable=True) artefact = Column(String, nullable=False) version = Column(String, nullable=False)

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  • SQL SERVER – What is Spatial Database? – Developing with SQL Server Spatial and Deep Dive into Spati

    - by pinaldave
    What is Spatial Database? A spatial database is a database that is optimized to store and query data related to objects in space, including points, lines and polygons. While typical databases can understand various numeric and character types of data, additional functionality needs to be added for databases to process spatial data types. (Source: Wikipedia) Today I will be talking about the same subject at Microsoft TechEd India. If you want to learn about how to spatial aspect of data and how to integrate them with SQL Server this is the perfect session for you. Spatial is very special concept of SQL Server and I really like how it is implemented in SQL Server. In general Performance Tuning and Query Optimization is something I always have enjoyed in my professional life. Index are my best friends and many time, by implementing and many time by removing I have improved the performance of the system. In this session, I will be talking about Index along with Spatial Data. As Spatial Database is very interesting concept, I will cover super short but very interesting 10 quick slides about this subject. I will make sure in very first 20 mins, you will understand following topics Introduction to Spatial Database One line definition Understanding Spatial Indexing Index Internals Query/Performance Tuning Query Hinting/Cost Analysis Spatial Index Catalog Views Performance Troubleshooting Finding Optimal Index using Spatial Index SP Common Errors Index Maintenance This slides decks will be followed by around 30 mins demo which will have story of geometry, geography, index internals and performance tuning. If you are interested in learning how GIS works and how SQL Server out of the box supports this wonderful tools, you will really like how the story is told. I am sure all people who attend the event will know how the Bangalore is positioned on the map of India. I will take example of Bangalore and Hyderabad and demonstrate how index can improve the performance. Well there are lots of story to tell in the session, and I will be opening this session with the beautiful script of Botticelli’s Birth of Venus created by Michael J. Swart. I will also demonstrate few real life scenario where I will be talking about Spatial Database and its usage. Do not miss this session. At the end of session there will be book awarded to best participant. My session details: Session 3: Developing with SQL Server Spatial and Deep Dive into Spatial Indexing Date: April 14, 2010 Time: 5:00pm-6:00pm Microsoft SQL Server 2008 delivers new spatial data types that enable you to consume, use, and extend location-based data through spatial-enabled applications. Attend this session to learn how to use spatial functionality in next version of SQL Server to build and optimize spatial queries. This session outlines the new geography data type to store geodetic spatial data and perform operations on it, use the new geometry data type to store planar spatial data and perform operations on it, take advantage of new spatial indexes for high performance queries, use the new spatial results tab to quickly and easily view spatial query results directly from within Management Studio, extend spatial data capabilities by building or integrating location-enabled applications through support for spatial standards and specifications and much more. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Index, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, T SQL, Technology Tagged: Spatial Database

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  • SQL SERVER – SOS_SCHEDULER_YIELD – Wait Type – Day 8 of 28

    - by pinaldave
    This is a very interesting wait type and quite often seen as one of the top wait types. Let us discuss this today. From Book On-Line: Occurs when a task voluntarily yields the scheduler for other tasks to execute. During this wait the task is waiting for its quantum to be renewed. SOS_SCHEDULER_YIELD Explanation: SQL Server has multiple threads, and the basic working methodology for SQL Server is that SQL Server does not let any “runnable” thread to starve. Now let us assume SQL Server OS is very busy running threads on all the scheduler. There are always new threads coming up which are ready to run (in other words, runnable). Thread management of the SQL Server is decided by SQL Server and not the operating system. SQL Server runs on non-preemptive mode most of the time, meaning the threads are co-operative and can let other threads to run from time to time by yielding itself. When any thread yields itself for another thread, it creates this wait. If there are more threads, it clearly indicates that the CPU is under pressure. You can fun the following DMV to see how many runnable task counts there are in your system. SELECT scheduler_id, current_tasks_count, runnable_tasks_count, work_queue_count, pending_disk_io_count FROM sys.dm_os_schedulers WHERE scheduler_id < 255 GO If you notice a two-digit number in runnable_tasks_count continuously for long time (not once in a while), you will know that there is CPU pressure. The two-digit number is usually considered as a bad thing; you can read the description of the above DMV over here. Additionally, there are several other counters (%Processor Time and other processor related counters), through which you can refer to so you can validate CPU pressure along with the method explained above. Reducing SOS_SCHEDULER_YIELD wait: This is the trickiest part of this procedure. As discussed, this particular wait type relates to CPU pressure. Increasing more CPU is the solution in simple terms; however, it is not easy to implement this solution. There are other things that you can consider when this wait type is very high. Here is the query where you can find the most expensive query related to CPU from the cache Note: The query that used lots of resources but is not cached will not be caught here. SELECT SUBSTRING(qt.TEXT, (qs.statement_start_offset/2)+1, ((CASE qs.statement_end_offset WHEN -1 THEN DATALENGTH(qt.TEXT) ELSE qs.statement_end_offset END - qs.statement_start_offset)/2)+1), qs.execution_count, qs.total_logical_reads, qs.last_logical_reads, qs.total_logical_writes, qs.last_logical_writes, qs.total_worker_time, qs.last_worker_time, qs.total_elapsed_time/1000000 total_elapsed_time_in_S, qs.last_elapsed_time/1000000 last_elapsed_time_in_S, qs.last_execution_time, qp.query_plan FROM sys.dm_exec_query_stats qs CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) qt CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle) qp ORDER BY qs.total_worker_time DESC -- CPU time You can find the most expensive queries that are utilizing lots of CPU (from the cache) and you can tune them accordingly. Moreover, you can find the longest running query and attempt to tune them if there is any processor offending code. Additionally, pay attention to total_worker_time because if that is also consistently higher, then  the CPU under too much pressure. You can also check perfmon counters of compilations as they tend to use good amount of CPU. Index rebuild is also a CPU intensive process but we should consider that main cause for this query because that is indeed needed on high transactions OLTP system utilized to reduce fragmentations. Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All of the discussions of Wait Stats in this blog is generic and varies from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • SQL SERVER – Error: Fix – Msg 208 – Invalid object name ‘dbo.backupset’ – Invalid object name ‘dbo.backupfile’

    - by pinaldave
    Just a day before I got a very interesting email. Here is the email (modified a bit to make it relevant to this blog post). “Pinal, We are facing a very strange issue. One of our query  related to backup files and backup set has stopped working suddenly in SSMS. It works fine in application where we have and in the stored procedure but when we have it in our SSMS it gives following error. Msg 208, Level 16, State 1, Line 1 Invalid object name ‘dbo.backupfile’. Here are our queries which we are trying to execute. SELECT name, database_name, backup_size, TYPE, compatibility_level, backup_set_id FROM dbo.backupset; SELECT logical_name, backup_size, file_type FROM dbo.backupfile; This query gives us details related to backupset and backup files when the backup was taken.” When I receive this kind of email, usually I have no answers directly. The claim that it works in stored procedure and in application but not in SSMS gives me no real data. I have requested him to very first check following two things: If he is connected to correct server? His answer was yes. If he has enough permissions? His answer was he was logged in as an admin. This means there was something more to it and I requested him to send me a screenshot of the his SSMS. He promptly sends that to me and as soon as I receive the screen shot I knew what was going on. Before I say anything take a look at the screenshot yourself and see if you can figure out why his queries are not working in SSMS. Just to make your life a bit easy, I have already given a hint in the image. The answer is very simple, the context of the database is master database. To execute above two queries the context of the database has to be msdb. Tables backupset and backupfile belong to the database msdb only. Here are two workaround or solution to above problem: 1) Change context to MSDB Above two queries when they will run as following they will not error out and will give the accurate desired result. USE msdb GO SELECT name, database_name, backup_size, TYPE, compatibility_level, backup_set_id FROM dbo.backupset; SELECT logical_name, backup_size, file_type FROM dbo.backupfile; 2) Prefix the query with msdb There are cases above script used in stored procedure or part of big query, it is not possible to change the context of the whole query to any specific database. Use three part naming convention and prefix them with msdb. SELECT name, database_name, backup_size, TYPE, compatibility_level, backup_set_id FROM msdb.dbo.backupset; SELECT logical_name, backup_size, file_type FROM msdb.dbo.backupfile; Very simple solution but sometime keeps people wondering for an answer. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Error Messages, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Data Pages in Buffer Pool – Data Stored in Memory Cache

    - by pinaldave
    This will drop all the clean buffers so we will be able to start again from there. Now, run the following script and check the execution plan of the query. Have you ever wondered what types of data are there in your cache? During SQL Server Trainings, I am usually asked if there is any way one can know how much data in a table is stored in the memory cache? The more detailed question I usually get is if there are multiple indexes on table (and used in a query), were the data of the single table stored multiple times in the memory cache or only for a single time? Here is a query you can run to figure out what kind of data is stored in the cache. USE AdventureWorks GO SELECT COUNT(*) AS cached_pages_count, name AS BaseTableName, IndexName, IndexTypeDesc FROM sys.dm_os_buffer_descriptors AS bd INNER JOIN ( SELECT s_obj.name, s_obj.index_id, s_obj.allocation_unit_id, s_obj.OBJECT_ID, i.name IndexName, i.type_desc IndexTypeDesc FROM ( SELECT OBJECT_NAME(OBJECT_ID) AS name, index_id ,allocation_unit_id, OBJECT_ID FROM sys.allocation_units AS au INNER JOIN sys.partitions AS p ON au.container_id = p.hobt_id AND (au.type = 1 OR au.type = 3) UNION ALL SELECT OBJECT_NAME(OBJECT_ID) AS name, index_id, allocation_unit_id, OBJECT_ID FROM sys.allocation_units AS au INNER JOIN sys.partitions AS p ON au.container_id = p.partition_id AND au.type = 2 ) AS s_obj LEFT JOIN sys.indexes i ON i.index_id = s_obj.index_id AND i.OBJECT_ID = s_obj.OBJECT_ID ) AS obj ON bd.allocation_unit_id = obj.allocation_unit_id WHERE database_id = DB_ID() GROUP BY name, index_id, IndexName, IndexTypeDesc ORDER BY cached_pages_count DESC; GO Now let us run the query above and observe the output of the same. We can see in the above query that there are four columns. Cached_Pages_Count lists the pages cached in the memory. BaseTableName lists the original base table from which data pages are cached. IndexName lists the name of the index from which pages are cached. IndexTypeDesc lists the type of index. Now, let us do one more experience here. Please note that you should not run this test on a production server as it can extremely reduce the performance of the database. DBCC DROPCLEANBUFFERS This will drop all the clean buffers and we will be able to start again from there. Now run following script and check the execution plan for the same. USE AdventureWorks GO SELECT UnitPrice, ModifiedDate FROM Sales.SalesOrderDetail WHERE SalesOrderDetailID BETWEEN 1 AND 100 GO The execution plans contain the usage of two different indexes. Now, let us run the script that checks the pages cached in SQL Server. It will give us the following output. It is clear from the Resultset that when more than one index is used, datapages related to both or all of the indexes are stored in Memory Cache separately. Let me know what you think of this article. I had a great pleasure while writing this article because I was able to write on this subject, which I like the most. In the next article, we will exactly see what data are cached and those that are not cached, using a few undocumented commands. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: DMV, Pinal Dave, SQL, SQL Authority, SQL Optimization, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: SQL DMV

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  • automatic manipulation of email messages

    - by Toc
    Does it exist any web service that "filters" any email message allowing to change the subject or the content on a regexp basis and then forward it to my webmail address? For example: I want to append automatically the string "IMPORTANT! " to the subject of every message I receive with the subject containing "expiry", or I want to change any occurrence of "h2" in the body to "h1".

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  • Slow manipulation of netfilter rules

    - by Ole Martin Eide
    I have a script maintaining gre tunnels and firewall rules using the "ip" and "iptables" tools. Setting up hundreds of tunnels, and adresses per interface runs just fine. Takes less than 0.1 second per interface, however when I get around to do the firewall rules everything slows down spending 0.5 per insertion. Why is it running so slow? What can I do to improve the speed? It seems like I could try ipset instead, but I really feel there is something wrong with the kernel or something. The interesting thing is that the first 10 rules runs fast, then it slows down.. mybox(root) foo# iptables -V iptables v1.3.5 mybox(root) foo# uname -a Linux foo 2.6.18-164.el5 #1 SMP Tue Aug 18 15:51:48 EDT 2009 x86_64 x86_64 x86_64 GNU/Linux mybox(root) foo# cat test.sh #!/bin/sh for n in {1..100} do /sbin/iptables -A OUTPUT -s ${n} -j ACCEPT /sbin/iptables -D OUTPUT -s ${n} -j ACCEPT done mybox(root) foo# time ./test.sh real 1m38.839s user 0m0.100s sys 1m38.724s Appriciate any help. Cheers!

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