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• SQL SERVER – CXPACKET – Parallelism – Usual Solution – Wait Type – Day 6 of 28

  - by pinaldave

  CXPACKET has to be most popular one of all wait stats. I have commonly seen this wait stat as one of the top 5 wait stats in most of the systems with more than one CPU. Books On-Line: Occurs when trying to synchronize the query processor exchange iterator. You may consider lowering the degree of parallelism if contention on this wait type becomes a problem. CXPACKET Explanation: When a parallel operation is created for SQL Query, there are multiple threads for a single query. Each query deals with a different set of the data (or rows). Due to some reasons, one or more of the threads lag behind, creating the CXPACKET Wait Stat. There is an organizer/coordinator thread (thread 0), which takes waits for all the threads to complete and gathers result together to present on the client’s side. The organizer thread has to wait for the all the threads to finish before it can move ahead. The Wait by this organizer thread for slow threads to complete is called CXPACKET wait. Note that not all the CXPACKET wait types are bad. You might experience a case when it totally makes sense. There might also be cases when this is unavoidable. If you remove this particular wait type for any query, then that query may run slower because the parallel operations are disabled for the query. Reducing CXPACKET wait: We cannot discuss about reducing the CXPACKET wait without talking about the server workload type. OLTP: On Pure OLTP system, where the transactions are smaller and queries are not long but very quick usually, set the “Maximum Degree of Parallelism” to 1 (one). This way it makes sure that the query never goes for parallelism and does not incur more engine overhead. EXEC sys.sp_configure N'cost threshold for parallelism', N'1' GO RECONFIGURE WITH OVERRIDE GO Data-warehousing / Reporting server: As queries will be running for long time, it is advised to set the “Maximum Degree of Parallelism” to 0 (zero). This way most of the queries will utilize the parallel processor, and long running queries get a boost in their performance due to multiple processors. EXEC sys.sp_configure N'cost threshold for parallelism', N'0' GO RECONFIGURE WITH OVERRIDE GO Mixed System (OLTP & OLAP): Here is the challenge. The right balance has to be found. I have taken a very simple approach. I set the “Maximum Degree of Parallelism” to 2, which means the query still uses parallelism but only on 2 CPUs. However, I keep the “Cost Threshold for Parallelism” very high. This way, not all the queries will qualify for parallelism but only the query with higher cost will go for parallelism. I have found this to work best for a system that has OLTP queries and also where the reporting server is set up. Here, I am setting ‘Cost Threshold for Parallelism’ to 25 values (which is just for illustration); you can choose any value, and you can find it out by experimenting with the system only. In the following script, I am setting the ‘Max Degree of Parallelism’ to 2, which indicates that the query that will have a higher cost (here, more than 25) will qualify for parallel query to run on 2 CPUs. This implies that regardless of the number of CPUs, the query will select any two CPUs to execute itself. EXEC sys.sp_configure N'cost threshold for parallelism', N'25' GO EXEC sys.sp_configure N'max degree of parallelism', N'2' GO RECONFIGURE WITH OVERRIDE GO Read all the post in the Wait Types and Queue series. Additionally a must read comment of Jonathan Kehayias. Note: The information presented here is from my experience and I no way claim it to be accurate. I suggest you all to read the online book for further clarification. All the discussion of Wait Stats over here is generic and it varies from system to system. It is recommended that you test this on the development server before implementing on the production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: DMV, 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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• What does SQL Server trace flag 253 do?

  - by kamens

  In another question I was trying to research how to control SQL Server's query plan caches: http://stackoverflow.com/questions/2593749/is-there-an-equivalent-of-optionrecompile-or-with-recompile-for-an-entire-c ...and I found trace flag 253 via this article: http://www.sqlservercentral.com/Forums/Topic837613-146-1.aspx The article is correct, if I run DBCC TRACEON(253) and then a number of queries, I can manually check the query plan cache and see that plans have not been inserted. If I run DBCC TRACEOFF(253), query plans are cached as normal. So my question is...what else does this flag do? Does anybody know the official story?

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• MySQL limit from descending order

  - by faya

  Hello, Is it available to write a query to use same "LIMIT (from), (count)", but get result in backwards? In example if I have 8 rows in the table and I want to get 5 rows in two steps I would: first step query: select * from table limit 0, 5 first step result: first 5 rows; second step query: select * from table limit 5, 5 second step result: last 3 rows; But I want to get it vice versa. I mean from the first step I want last 3 rows and from the second I want 5 first rows. Thank you for your answer

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• mysql inserts & updates optimized

  - by user271619

  This is an optimization question, mostly. I have many forms on my sites that do simple Inserts and Updates. (Nothing complicated) But, several of the form's input fields are not necessary and may be left empty. (again, nothing complicated) However, my SQL query will have all columns in the Statement. My question, is it best to optimize the Inserts/Update queries appropriately? And only apply the columns that are changed into the query? We all hear that we shouldn't use the "SELECT *" query, unless it's absolutely needed for displaying all columns. But what about Inserts & Updates? Hope this makes sense. I'm sure any amount of optimization is acceptable. But I never really hear about this, specifically, from anyone.

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• Should I have a separate method for Update(), Insert(), etc., or have a generic Query() that would be able to handle all of these?

  - by Prayos

  I'm currently trying to write a class library for a connection to a database. Looking over it, there are several different types of queries: Select From, Update, Insert, etc. My question is, what is the best practice for writing these queries in a C# application? Should I have a separate method for each of them(i.e. Update(), Insert()), or have a generic Query() that would be able to handle all of these? Thanks for any and all help!

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• SQL SERVER – Reducing CXPACKET Wait Stats for High Transactional Database

  - by pinaldave

  While engaging in a performance tuning consultation for a client, a situation occurred where they were facing a lot of CXPACKET Waits Stats. The client asked me if I could help them reduce this huge number of wait stats. I usually receive this kind of request from other client as well, but the important thing to understand is whether this question has any merits or benefits, or not. Before we continue the resolution, let us understand what CXPACKET Wait Stats are. The official definition suggests that CXPACKET Wait Stats occurs when trying to synchronize the query processor exchange iterator. You may consider lowering the degree of parallelism if a conflict concerning this wait type develops into a problem. (from BOL) In simpler words, when a parallel operation is created for SQL Query, there are multiple threads for a single query. Each query deals with a different set of the data (or rows). Due to some reasons, one or more of the threads lag behind, creating the CXPACKET Wait Stat. Threads which came first have to wait for the slower thread to finish. The Wait by a specific completed thread is called CXPACKET Wait Stat. Note that CXPACKET Wait is done by completed thread and not the one which are unfinished. “Note that not all the CXPACKET wait types are bad. You might experience a case when it totally makes sense. There might also be cases when this is also unavoidable. If you remove this particular wait type for any query, then that query may run slower because the parallel operations are disabled for the query.” Now let us see what the best practices to reduce the CXPACKET Wait Stats are. The suggestions, with which you will find that if you search online through the browser, would play a major role as and might be asked about their jobs In addition, might tell you that you should set ‘maximum degree of parallelism’ to 1. I do agree with these suggestions, too; however, I think this is not the final resolutions. As soon as you set your entire query to run on single CPU, you will get a very bad performance from the queries which are actually performing okay when using parallelism. The best suggestion to this is that you set ‘the maximum degree of parallelism’ to a lower number or 1 (be very careful with this – it can create more problems) but tune the queries which can be benefited from multiple CPU’s. You can use query hint OPTION (MAXDOP 0) to run the server to use parallelism. Here is the two-quick script which helps to resolve these issues: Change MAXDOP at Server Level EXEC sys.sp_configure N'max degree of parallelism', N'1' GO RECONFIGURE WITH OVERRIDE GO Run Query with all the CPU (using parallelism) USE AdventureWorks GO SELECT * FROM Sales.SalesOrderDetail ORDER BY ProductID OPTION (MAXDOP 0) GO Below is the blog post which will help you to find all the parallel query in your server. SQL SERVER – Find Queries using Parallelism from Cached Plan Please note running Queries in single CPU may worsen your performance and it is not recommended at all. Infect this can be very bad advise. I strongly suggest that you identify the queries which are offending and tune them instead of following any other suggestions. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQL White Papers, SQLAuthority News, T SQL, Technology

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• SQL SERVER – Simple Demo of New Cardinality Estimation Features of SQL Server 2014

  - by Pinal Dave

  SQL Server 2014 has new cardinality estimation logic/algorithm. The cardinality estimation logic is responsible for quality of query plans and majorly responsible for improving performance for any query. This logic was not updated for quite a while, but in the latest version of SQL Server 2104 this logic is re-designed. The new logic now incorporates various assumptions and algorithms of OLTP and warehousing workload. Cardinality estimates are a prediction of the number of rows in the query result. The query optimizer uses these estimates to choose a plan for executing the query. The quality of the query plan has a direct impact on improving query performance. ~ Souce MSDN Let us see a quick example of how cardinality improves performance for a query. I will be using the AdventureWorks database for my example. Before we start with this demonstration, remember that even though you have SQL Server 2014 to see the effect of new cardinality estimates, you will need your database compatibility mode set to 120 which is for SQL Server 2014. If your server instance of SQL Server 2014 but you have set up your database compatibility mode to 110 or any other earlier version, you will get performance from your query like older version of SQL Server. Now we will execute following query in two different compatibility mode and see its performance. (Note that my SQL Server instance is of version 2014). USE AdventureWorks2014 GO -- ------------------------------- -- NEW Cardinality Estimation ALTER DATABASE AdventureWorks2014 SET COMPATIBILITY_LEVEL = 120 GO EXEC [dbo].[uspGetManagerEmployees] 44 GO -- ------------------------------- -- Old Cardinality Estimation ALTER DATABASE AdventureWorks2014 SET COMPATIBILITY_LEVEL = 110 GO EXEC [dbo].[uspGetManagerEmployees] 44 GO Result of Statistics IO Compatibility level 120 Table ‘Person’. Scan count 0, logical reads 6, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0. Table ‘Employee’. Scan count 2, logical reads 7, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0. Table ‘Worktable’. Scan count 0, logical reads 0, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0. Table ‘Worktable’. Scan count 2, logical reads 7, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0. Compatibility level 110 Table ‘Worktable’. Scan count 2, logical reads 7, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0. Table ‘Person’. Scan count 0, logical reads 137, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0. Table ‘Employee’. Scan count 2, logical reads 7, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0. Table ‘Worktable’. Scan count 0, logical reads 0, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0. You will notice in the case of compatibility level 110 there 137 logical read from table person where as in the case of compatibility level 120 there are only 6 physical reads from table person. This drastically improves the performance of the query. If we enable execution plan, we can see the same as well. I hope you will find this quick example helpful. You can read more about this in my latest Pluralsight Course. Reference: Pinal Dave (http://blog.SQLAuthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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• SQL SERVER – DMV – sys.dm_os_waiting_tasks and sys.dm_exec_requests – Wait Type – Day 4 of 28

  - by pinaldave

  Previously, we covered the DMV sys.dm_os_wait_stats, and also saw how it can be useful to identify the major resource bottleneck. However, at the same time, we discussed that this is only useful when we are looking at an instance-level picture. Quite often we want to know about the processes going in our server at the given instant. Here is the query for the same. This DMV is written taking the following into consideration: we want to analyze the queries that are currently running or which have recently ran and their plan is still in the cache. SELECT dm_ws.wait_duration_ms, dm_ws.wait_type, dm_es.status, dm_t.TEXT, dm_qp.query_plan, dm_ws.session_ID, dm_es.cpu_time, dm_es.memory_usage, dm_es.logical_reads, dm_es.total_elapsed_time, dm_es.program_name, DB_NAME(dm_r.database_id) DatabaseName, -- Optional columns dm_ws.blocking_session_id, dm_r.wait_resource, dm_es.login_name, dm_r.command, dm_r.last_wait_type FROM sys.dm_os_waiting_tasks dm_ws INNER JOIN sys.dm_exec_requests dm_r ON dm_ws.session_id = dm_r.session_id INNER JOIN sys.dm_exec_sessions dm_es ON dm_es.session_id = dm_r.session_id CROSS APPLY sys.dm_exec_sql_text (dm_r.sql_handle) dm_t CROSS APPLY sys.dm_exec_query_plan (dm_r.plan_handle) dm_qp WHERE dm_es.is_user_process = 1 GO You can change CROSS APPLY to OUTER APPLY if you want to see all the details which are omitted because of the plan cache. Let us analyze the result of the above query and see how it can be helpful to identify the query and the kind of wait type it creates. Click to Enlarage The above query will return various columns. There are various columns that provide very important details. e.g. wait_duration_ms – it indicates current wait for the query that executes at that point of time. wait_type – it indicates the current wait type for the query text – indicates the query text query_plan – when clicked on the same, it will display the query plans There are many other important information like CPU_time, memory_usage, and logical_reads, which can be read from the query as well. In future posts on this series, we will see how once identified wait type we can attempt to reduce the same. Read all the post in the Wait Types and Queue series. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: DMV, Pinal Dave, PostADay, SQL, SQL Authority, SQL DMV, 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 – Quiz and Video – Introduction to Discovering XML Data Type Methods

  - by pinaldave

  This blog post is inspired from SQL Interoperability Joes 2 Pros: A Guide to Integrating SQL Server with XML, C#, and PowerShell – SQL Exam Prep Series 70-433 – Volume 5. [Amazon] | [Flipkart] | [Kindle] | [IndiaPlaza] This is follow up blog post of my earlier blog post on the same subject - SQL SERVER – Introduction to Discovering XML Data Type Methods – A Primer. In the article we discussed various basics terminology of the XML. The article further covers following important concepts of XML. What are XML Data Type Methods The query() Method The value() Method The exist() Method The modify() Method Above five are the most important concepts related to XML and SQL Server. There are many more things one has to learn but without beginners fundamentals one can’t learn the advanced  concepts. Let us have small quiz and check how many of you get the fundamentals right. Quiz 1.) Which method returns an XML fragment from the source XML? query( ) value( ) exist( ) modify( ) All of them Only query( ) and value( ) 2.) Which XML data type method returns a “1” if found and “0” if the specified XPath is not found in the source XML? query( ) value( ) exist( ) modify( ) All of them Only query( ) and value( ) 3.) Which XML data type method allows you to pick the data type of the value that is returned from the source XML? query( ) value( ) exist( ) modify( ) All of them Only query( ) and value( ) 4.) Which method will not work with a SQL SELECT statement? query( ) value( ) exist( ) modify( ) All of them Only query( ) and value( ) Now make sure that you write down all the answers on the piece of paper. Watch following video and read earlier article over here. If you want to change the answer you still have chance. Solution 1) 1 2) 3 3) 2 4) 4 Now compare let us check the answers and compare your answers to following answers. I am very confident you will get them correct. Available at USA: Amazon India: Flipkart | IndiaPlaza Volume: 1, 2, 3, 4, 5 Please leave your feedback in the comment area for the quiz and video. Did you know all the answers of the quiz? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Joes 2 Pros, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• Will removing unused query string parameters negatively affect SEO?

  - by trm

  Will changing links to remove query string parameters that are no longer used have any negative impact on search engine rankings? Say I have a page about.php on my site, and all of my links to this page are of the form http://www.example.com/about.php?foo=bar and I've made some changes to the script such that the parameter foo is no longer used. I would like to remove the unused parameter from the links so the URL will look cleaner, but I am concerned that this could cause problems with SEO. Is it safe to remove ?foo=bar from my links?

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• "Delete query" not able to be completed

  - by mingyeow

  I have a very simple mysql script that is running. But it hangs, and runs forever without finishing. What are possible reasons, and how can I resolve them? delete from guid_target_infos where type_id = 1 and updated_at < '2010-03-14' limit 1

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• Linq-to-sql Compiled Query returning object NOT belonging to submitted DataContext

  - by Vladimir Kojic

  Compiled query: public static class Machines { public static readonly Func<OperationalDataContext, short, Machine> QueryMachineById = CompiledQuery.Compile((OperationalDataContext db, short machineID) => db.Machines.Where(m => m.MachineID == machineID).SingleOrDefault() ); public static Machine GetMachineById(IUnitOfWork unitOfWork, short id) { Machine machine; // Old code (working) //var machineRepository = unitOfWork.GetRepository<Machine>(); //machine = machineRepository.Find(m => m.MachineID == id).SingleOrDefault(); // New code (making problems) machine = QueryMachineById(unitOfWork.DataContext, id); return machine; } It looks like compiled query is caching Machine object and returning the same object even if query is called from new DataContext (I’m disposing DataContext in the service but I’m getting Machine from previous DataContext). I use POCOs and XML mapping. Revised: It looks like compiled query is returning result from new data context and it is not using the one that I passed in compiled-query. Therefore I can not reuse returned object and link it to another object obtained from datacontext thru non compiled queries. [TestMethod] public void GetMachinesTest() { // Test Preparation (not important) using (var unitOfWork = IoC.Get<IUnitOfWork>()) { var machineRepository = unitOfWork.GetRepository<Machine>(); // GET ALL List<Machine> list = machineRepository.FindAll().ToList<Machine>(); VerifyIntegratedMachine(list[2], 3, "Machine 3", "333333", "G300PET", "MachineIconC.xaml", false, true, LicenseType.Licensed, "10.0.97.3", "10.0.97.3", 0); var machine = Machines.GetMachineById(unitOfWork, 3); Assert.AreSame(list[2], machine); // PASS !!!! } using (var unitOfWork = IoC.Get<IUnitOfWork>()) { var machineRepository = unitOfWork.GetRepository<Machine>(); // GET ALL List<Machine> list = machineRepository.FindAll().ToList<Machine>(); VerifyIntegratedMachine(list[2], 3, "Machine 3", "333333", "G300PET", "MachineIconC.xaml", false, true, LicenseType.Licensed, "10.0.97.3", "10.0.97.3", 0); var machine = Machines.GetMachineById(unitOfWork, 3); Assert.AreSame(list[2], machine); // FAIL !!!! } } If I run other (complex) unit tests I'm getting as expected: An attempt has been made to Attach or Add an entity that is not new, perhaps having been loaded from another DataContext.

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• solr JOIN query

  - by Sfairas

  I need to run a JOIN query on a solr index. I've got two xmls that I have indexed, person.xml and subject.xml. Person: <doc> <field name="id">P39126</field> <field name="family">Smith</field> <field name="given">John</field> <field name="subject">S1276</field> <field name="subject">S1312</field> </doc> Subject: <doc> <field name="id">S1276</field> <field name="topic">Abnormalities, Human</field> </doc> I need to only display information from the person doc but each query should match fields in both person and subject. In the case the query matches only the subject doc I need to display all docs from the person that have a matching id. Is this possible to do without running two seperate queries? Something like a JOIN query would do the job. Any help?

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• Prevent full table scan for query with multiple where clauses

  - by Dave Jarvis

  A while ago I posted a message about optimizing a query in MySQL. I have since ported the data and query to PostgreSQL, but now PostgreSQL has the same problem. The solution in MySQL was to force the optimizer to not optimize using STRAIGHT_JOIN. PostgreSQL offers no such option. Here is the explain: Here is the query: SELECT avg(d.amount) AS amount, y.year FROM station s, station_district sd, year_ref y, month_ref m, daily d LEFT JOIN city c ON c.id = 10663 WHERE -- Find all the stations within a specific unit radius ... -- 6371.009 * SQRT( POW(RADIANS(c.latitude_decimal - s.latitude_decimal), 2) + (COS(RADIANS(c.latitude_decimal + s.latitude_decimal) / 2) * POW(RADIANS(c.longitude_decimal - s.longitude_decimal), 2)) ) <= 50 AND -- Ignore stations outside the given elevations -- s.elevation BETWEEN 0 AND 2000 AND sd.id = s.station_district_id AND -- Gather all known years for that station ... -- y.station_district_id = sd.id AND -- The data before 1900 is shaky; insufficient after 2009. -- y.year BETWEEN 1980 AND 2000 AND -- Filtered by all known months ... -- m.year_ref_id = y.id AND m.month = 12 AND -- Whittled down by category ... -- m.category_id = '001' AND -- Into the valid daily climate data. -- m.id = d.month_ref_id AND d.daily_flag_id <> 'M' GROUP BY y.year It appears as though PostgreSQL is looking at the DAILY table first, which is simply not the right way to go about this query as there are nearly 300 million rows. How do I force PostgreSQL to start at the CITY table? Thank you!

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• Increase Query Speed in PostgreSQL

  - by Anthoni Gardner

  Hello, First time posting here, but an avid reader. I am experiancing slow query times on my database (all tested locally thus far) and not sure how to go about it. The database itself has 44 tables and some of them tables have over 1 Million records (mainly the movies, actresses and actors tables). The table is made via JMDB using the flat files on IMDB. Also the SQL query that I am about to show is from that said program (that too experiances very slow search times). I have tried to include as much information as I can, such as the explain plan etc. "QUERY PLAN" "HashAggregate (cost=46492.52..46493.50 rows=98 width=46)" " Output: public.movies.title, public.movies.movieid, public.movies.year" " - Append (cost=39094.17..46491.79 rows=98 width=46)" " - HashAggregate (cost=39094.17..39094.87 rows=70 width=46)" " Output: public.movies.title, public.movies.movieid, public.movies.year" " - Seq Scan on movies (cost=0.00..39093.65 rows=70 width=46)" " Output: public.movies.title, public.movies.movieid, public.movies.year" " Filter: (((title)::text ~~* '%Babe%'::text) AND ((title)::text !~~* '""%}'::text))" " - Nested Loop (cost=0.00..7395.94 rows=28 width=46)" " Output: public.movies.title, public.movies.movieid, public.movies.year" " - Seq Scan on akatitles (cost=0.00..7159.24 rows=28 width=4)" " Output: akatitles.movieid, akatitles.language, akatitles.title, " Filter: (((title)::text ~~* '%Babe%'::text) AND ((title)::text !~~* '""%}'::text))" " - Index Scan using movies_pkey on movies (cost=0.00..8.44 rows=1 width=46)" " Output: public.movies.movieid, public.movies.title, public.movies.year, public.movies.imdbid" " Index Cond: (public.movies.movieid = akatitles.movieid)" SELECT * FROM ((SELECT DISTINCT title, movieid, year FROM movies WHERE title ILIKE '%Babe%' AND NOT (title ILIKE '"%}')) UNION (SELECT movies.title, movies.movieid, movies.year FROM movies INNER JOIN akatitles ON movies.movieid=akatitles.movieid WHERE akatitles.title ILIKE '%Babe%' AND NOT (akatitles.title ILIKE '"%}'))) AS union_tmp2; Returns 612 Rows in 9078ms Database backup (plain text) is 1.61GB It's a really complex query and I am not fully cognizant on it, like I said it was spat out by JMDB. Do you have any suggestions on how I can increase the speed ? Regards Anthoni

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• LINQ compiled query DataBind issue

  - by Brian

  Hello All, I have a pretty extensive reporting page that uses LINQ. There is one main function that returns an IQueryable object. I then further filter / aggregate the returned query depending on the report the user needs. I changed this function to a compiled query, it worked great, and the speed increase was astonishing. The only problem comes when i want to databind the results. I am databinding to a standard asp.net GridView and it works fine, no problems. I am also databinding to an asp.net chart control, this is where my page is throwing an error. this works well: GridView gv = new GridView(); gv.DataSource = gridSource; But this does not: Series s1 = new Series("Series One"); s1.Points.DataBindXY(gridSource, "Month", gridSource, "Success"); The error i receive is this: System.NotSupportedException Specified method is not supported When i look into my gridSource var at run time i see this using a typical linq query: SELECT [t33].[value2] AS [Year], [t33].[value22] AS [Month], [t33].[value3] AS [Calls]...... I see this after i change the query to compiled: {System.Linq.OrderedEnumerable<<>f__AnonymousType15<string,int,int,int,int,int,int,int>,string>} This is obviously the reason why the databindxy is no longer working, but i am not sure how to get around it. Any help would be appreciated! Thanks

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• Entity Framework query

  - by carter-boater

  Hi all, I have a piece of code that I don't know how to improve it. I have two entities: EntityP and EntityC. EntityP is the parent of EntityC. It is 1 to many relationship. EntityP has a property depending on a property of all its attached EntityC. I need to load a list of EntityP with the property set correctly. So I wrote a piece of code to get the EntityP List first.It's called entityP_List. Then as I wrote below, I loop through the entityP_List and for each of them, I query the database with a "any" function which will eventually be translated to "NOT EXIST" sql query. The reason I use this is that I don't want to load all the attached entityC from database to memory, because I only need the aggregation value of their property. But the problem here is, the looping will query the databae many times, for each EntityP! So I am wondering if anybody can help me improve the code to query the database only once to get all the EntityP.IsAll_C_Complete set, without load EntityC to memory. foreach(EntityP p in entityP_List) { isAnyNotComoplete = entities.entityC.Any(c => c.IsComplete==false && c.parent.ID == p.ID); p.IsAll_C_Complete = !isAnyNotComoplete; } Thank you very much!

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• A jscript variable in a Query

  - by lerac

  Maybe a very simple question. How can I put in this code <Query> <Where> <Eq> <FieldRef Name="Judge_x0020_1" /> <Value Type="Text">mr. R. Sanches</Value> </Eq> </Where> </script> </Query> A variable from jscript in the area of the code where mr. R. Sanches is written. So my jScript contains a dynamic text variable I want to replace mr. R. Sanches with. See where it says THE JAVESCRIPT VAR underneath here: <Query> <Where> <Eq> <FieldRef Name="Judge_x0020_1" /> <Value Type="Text">THE JAVASCRIPT VAR</Value> </Eq> </Where> </script> </Query>

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• MySQL Query Error

  - by Nano HE

  I am debug my php forum. Before the error,I modified the DB table name from cdb_sessions to imc_forum_sessions successfully. I tried my best to debug with NetBeans but can't find the reason. Could you please have a look at my post below. Thank you. // It will run to else during debug if($sid) { if($discuz_uid) { $query = $db->query("SELECT s.sid, s.styleid, s.groupid='6' AS ipbanned, s.pageviews AS spageviews, s.lastolupdate, s.seccode, $membertablefields FROM {$tablepre}sessions s, {$tablepre}members m WHERE m.uid=s.uid AND s.sid='$sid' AND CONCAT_WS('.',s.ip1,s.ip2,s.ip3,s.ip4)='$onlineip' AND m.uid='$discuz_uid' AND m.password='$discuz_pw' AND m.secques='$discuz_secques'"); } else { $query = $db->query("SELECT sid, uid AS sessionuid, groupid, groupid='6' AS ipbanned, pageviews AS spageviews, styleid, lastolupdate, seccode FROM {$tablepre}sessions WHERE sid='$sid' AND CONCAT_WS('.',ip1,ip2,ip3,ip4)='$onlineip'"); } } MySQL data table exported as below CREATE TABLE IF NOT EXISTS `imc_forum_sessions` ( `sid` char(6) NOT NULL DEFAULT '', `ip1` tinyint(3) unsigned NOT NULL DEFAULT '0', `ip2` tinyint(3) unsigned NOT NULL DEFAULT '0', `ip3` tinyint(3) unsigned NOT NULL DEFAULT '0', `ip4` tinyint(3) unsigned NOT NULL DEFAULT '0', `uid` mediumint(8) unsigned NOT NULL DEFAULT '0', `username` char(15) NOT NULL DEFAULT '', `groupid` smallint(6) unsigned NOT NULL DEFAULT '0', `styleid` smallint(6) unsigned NOT NULL DEFAULT '0', `invisible` tinyint(1) NOT NULL DEFAULT '0', `action` tinyint(1) unsigned NOT NULL DEFAULT '0', `lastactivity` int(10) unsigned NOT NULL DEFAULT '0', `lastolupdate` int(10) unsigned NOT NULL DEFAULT '0', `pageviews` smallint(6) unsigned NOT NULL DEFAULT '0', `seccode` mediumint(6) unsigned NOT NULL DEFAULT '0', `fid` smallint(6) unsigned NOT NULL DEFAULT '0', `tid` mediumint(8) unsigned NOT NULL DEFAULT '0', `bloguid` mediumint(8) unsigned NOT NULL DEFAULT '0', UNIQUE KEY `sid` (`sid`), KEY `uid` (`uid`), KEY `bloguid` (`bloguid`) ) ENGINE=MEMORY DEFAULT CHARSET=utf8 MAX_ROWS=5000; -- -- Dumping data for table `imc_forum_sessions` -- INSERT INTO `imc_forum_sessions` (`sid`, `ip1`, `ip2`, `ip3`, `ip4`, `uid`, `username`, `groupid`, `styleid`, `invisible`, `action`, `lastactivity`, `lastolupdate`, `pageviews`, `seccode`, `fid`, `tid`, `bloguid`) VALUES ('NYC4r7', 127, 0, 0, 1, 0, '', 6, 5, 0, 3, 1271372018, 0, 0, 939015, 51, 303, 0); And the IE error showed, Time: 2010-4-16 7:12am Script: /forum/index.php SQL: SELECT sid, uid AS sessionuid, groupid, groupid='6' AS ipbanned, pageviews AS spageviews, styleid, lastolupdate, seccode FROM [Table]sessions WHERE sid='NYC4r7' AND CONCAT_WS('.',ip1,ip2,ip3,ip4)='127.0.0.1' Error: Table 'dbbbs.[Table]sessions' doesn't exist Errno.: 1146 Similar error report has beed dispatched to administrator before.

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• Mysql - Help me alter this search query to get desired results

  - by sandeepan-nath

  Following is a dump of the tables and data needed to answer understand the system:- The system consists of tutors and classes. The data in the table All_Tag_Relations stores tag relations for each tutor registered and each class created by a tutor. The tag relations are used for searching classes. CREATE TABLE IF NOT EXISTS `Tags` ( `id_tag` int(10) unsigned NOT NULL auto_increment, `tag` varchar(255) default NULL, PRIMARY KEY (`id_tag`), UNIQUE KEY `tag` (`tag`), KEY `id_tag` (`id_tag`), KEY `tag_2` (`tag`), KEY `tag_3` (`tag`), KEY `tag_4` (`tag`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; INSERT INTO `Tags` (`id_tag`, `tag`) VALUES (1, 'Sandeepan'), (2, 'Nath'), (3, 'first'), (4, 'class'), (5, 'new'), (6, 'Bob'), (7, 'Cratchit'); CREATE TABLE IF NOT EXISTS `All_Tag_Relations` ( `id_tag` int(10) unsigned NOT NULL default '0', `id_tutor` int(10) default NULL, `id_wc` int(10) unsigned default NULL, KEY `All_Tag_Relations_FKIndex1` (`id_tag`), KEY `id_wc` (`id_wc`), KEY `id_tag` (`id_tag`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; INSERT INTO `All_Tag_Relations` (`id_tag`, `id_tutor`, `id_wc`) VALUES (1, 1, NULL), (2, 1, NULL), (3, 1, 1), (4, 1, 1), (6, 2, NULL), (7, 2, NULL), (5, 2, 2), (4, 2, 2); Following is my query:- This query searches for "first class" (tag for first = 3 and for class = 4, in Tags table) and returns all those classes such that both the terms first and class are present in the class name. SELECT wtagrels.id_wc,SUM(DISTINCT( wtagrels.id_tag =3)) AS key_1_total_matches, SUM(DISTINCT( wtagrels.id_tag =4)) AS key_2_total_matches FROM all_tag_relations AS wtagrels WHERE ( wtagrels.id_tag =3 OR wtagrels.id_tag =4 ) GROUP BY wtagrels.id_wc HAVING key_1_total_matches = 1 AND key_2_total_matches = 1 LIMIT 0, 20 And it returns the class with id_wc = 1. But, I want the search to show all those classes such that all the search terms are present in the class name or its tutor name So that searching "Sandeepan class" (wtagrels.id_tag = 1,4) or "Sandeepan Nath" also returns the class with id_wc=1. And Searching. Searching "Bob First" should not return any classes. Please modify the above query or suggest a new query, if possible using MyIsam - fulltext search, but somehow help me get the result.

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• Group functions of outer query inside inner query

  - by superdario

  Hello, I'm using Oracle. I'm trying to compose something like this: SELECT trans_type, (SELECT parameter_value FROM transaction_details WHERE id = MAX(t.trans_id)) FROM (SELECT trans_id, trans_type FROM transactions) t GROUP BY trans_type So, I am trying to use a result of grouping inside an inner query. But I am getting the error that I cannot use a group function inside the inner query: ORA-00934: group function is not allowed here Can you offer an alternative other than resorting to another outer query?

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• TFS query mixing Tasks and Bugs, sorted by Priority

  - by Val

  We're using TFS with MSF for Agile 4.2 on a project, and I have a bunch of work to do, both Tasks and Bugs. Both are prioritized by our managers, and assigned due dates and target releases. I use a Work Item query as my main TODO list, and I want to list all the Work Items assigned to me, in order by due date and priority. Problem: I can't seem to find a way to write a unified query that will list both Tasks and Bugs sorted by date and then priority. The problem is that Tasks and Bugs use different fields for Priority. So, my query currently lists the tasks by Due Date, then by Task Priority, then it lists Bugs by Due Date, then by Priority. So, I see tasks that are due later than bugs: Title Due Date Priority Task Priority task1 4/23/2010 Medium task2 4/23/2010 High task3 4/30/2010 Low task4 4/30/2010 Medium bug1 4/23/2010 1 bug2 4/23/2010 2 What I want: Title Due Date Priority Task Priority task1 4/23/2010 Medium task2 4/23/2010 High bug1 4/23/2010 1 bug2 4/23/2010 2 task3 4/30/2010 Low task4 4/30/2010 Medium I don't care if the bugs come before or after the tasks on the same due date; I just want all the work items grouped together by due date, so I never see Tasks for a later due date before Bugs for an earlier one. Another problem is the sorting on Task Priority -- alpha sort means I can't get them to sort by the meaning of the priority. But that's a minor problem I can live with if I can get the Tasks and Bugs intermingled. Any way to do this in a single query?

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• MySQL query does not return any data

  - by Alex L

  Hi, I need to retrieve data from a specific time period. The query works fine until I specify the time period. Is there something wrong with the way I specify time period? I know there are many entries within that time-frame. This query returns empty: SELECT stop_times.stop_id, STR_TO_DATE(stop_times.arrival_time, '%H:%i:%s') as stopTime, routes.route_short_name, routes.route_long_name, trips.trip_headsign FROM trips JOIN stop_times ON trips.trip_id = stop_times.trip_id JOIN routes ON routes.route_id = trips.route_id WHERE stop_times.stop_id = 5508 HAVING stopTime BETWEEN DATE_SUB(stopTime,INTERVAL 1 MINUTE) AND DATE_ADD(stopTime,INTERVAL 20 MINUTE); Here is it's EXPLAIN: +----+-------------+------------+--------+------------------+---------+---------+-------------------------------+------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+------------+--------+------------------+---------+---------+-------------------------------+------+-------------+ | 1 | SIMPLE | stop_times | ref | trip_id,stop_id | stop_id | 5 | const | 605 | Using where | | 1 | SIMPLE | trips | eq_ref | PRIMARY,route_id | PRIMARY | 4 | wmata_gtfs.stop_times.trip_id | 1 | | | 1 | SIMPLE | routes | eq_ref | PRIMARY | PRIMARY | 4 | wmata_gtfs.trips.route_id | 1 | | +----+-------------+------------+--------+------------------+---------+---------+-------------------------------+------+-------------+ 3 rows in set (0.00 sec) The query works if I remove the HAVING clause (don't specify time range). Returns: +---------+----------+------------------+-----------------+---------------+ | stop_id | stopTime | route_short_name | route_long_name | trip_headsign | +---------+----------+------------------+-----------------+---------------+ | 5508 | 06:31:00 | "80" | "" | "FORT TOTTEN" | | 5508 | 06:57:00 | "80" | "" | "FORT TOTTEN" | | 5508 | 07:23:00 | "80" | "" | "FORT TOTTEN" | | 5508 | 07:49:00 | "80" | "" | "FORT TOTTEN" | | 5508 | 08:15:00 | "80" | "" | "FORT TOTTEN" | | 5508 | 08:41:00 | "80" | "" | "FORT TOTTEN" | | 5508 | 09:08:00 | "80" | "" | "FORT TOTTEN" | I am using Google Transit format Data loaded into MySQL. The query is supposed to provide stop times and bus routes for a given bus stop. For a bus stop, I am trying to get: Route Name Bus Name Bus Direction (headsign) Stop time The results should be limited only to buses times from 1 min ago to 20 min from now. Please let me know if you could help.

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• How can get unique values from data table using dql?

  - by piemesons

  I am having a table in which there is a column in which various values are stored.i want to retrieve unique values from that table using dql. Doctrine_Query::create() ->select('rec.school') ->from('Records rec') ->where("rec.city='$city' ") ->execute(); Now i want only unique values. Can anybody tell me how to do that... Edit Table Structure: CREATE TABLE IF NOT EXISTS `records` ( `id` int(11) NOT NULL AUTO_INCREMENT, `state` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL, `city` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL, `school` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci AUTO_INCREMENT=16334 ; This is the Query I am using: Doctrine_Query::create() ->select('DISTINCT rec.city') ->from('Records rec') ->where("rec.state = '$state'") // ->getSql(); ->execute(); Generting Sql for this gives me: SELECT DISTINCT r.id AS r__id, r.city AS r__city FROM records r WHERE r.state = 'AR' Now check the sql generated:::: DISTINCT is on 'id' column where as i want Distinct on city column. Anybody know how to fix this. EDIT2 Id is unique cause its an auto incremental value.Ya i have some real duplicates in city column like: Delhi and Delhi. Right.. Now when i am trying to fetch data from it, I am getting Delhi two times. How can i make query like this: select DISTINCT rec.city where state="xyz"; Cause this will give me the proper output. EDIT3: Anybody who can tell me how to figure out this query..???

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• How Optimize sql query make it faster

  - by user502083

  Hello every one : I have a very simple small database, 2 of tables are: Node (Node_ID, Node_name, Node_Date) : Node_ID is primary key Citation (Origin_Id, Target_Id) : PRIMARY KEY (Origin_Id, Target_Id) each is FK in Node Now I write a query that first find all citations that their Origin_Id has a specific date and then I want to know what are the target dates of these records. I'm using sqlite in python the Node table has 3000 record and Citation has 9000 records, and my query is like this in a function: def cited_years_list(self, date): c=self.cur try: c.execute("""select n.Node_Date,count(*) from Node n INNER JOIN (select c.Origin_Id AS Origin_Id, c.Target_Id AS Target_Id, n.Node_Date AS Date from CITATION c INNER JOIN NODE n ON c.Origin_Id=n.Node_Id where CAST(n.Node_Date as INT)={0}) VW ON VW.Target_Id=n.Node_Id GROUP BY n.Node_Date;""".format(date)) cited_years=c.fetchall() self.conn.commit() print('Cited Years are : \n ',str(cited_years)) except Exception as e: print('Cited Years retrival failed ',e) return cited_years Then I call this function for some specific years, But it's crazy slowwwwwwwww :( (around 1 min for a specific year) Although my query works fine, it is slow. would you please give me a suggestion to make it faster? I'd appreciate any idea about optimizing this query :) I also should mention that I have indices on Origin_Id and Target_Id, so the inner join should be pretty fast, but it's not!!!

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