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  • July, the 31 Days of SQL Server DMO’s – Day 1 (sys.dm_exec_requests)

    - by Tamarick Hill
    The first DMO that I would like to introduce you to is one of the most common and basic DMV’s out there. I use the term DMV because this DMO is actually a view as opposed to a function. This DMV is server-scoped and it returns information about all requests that are currently executing on your SQL Server instance. To illustrate what this DMV returns, lets take a look at the results. As you can see, this DMV returns a wealth of information about requests occurring on your server. You are able to see the SPID, the start time of a request, current status, and the command the SPID is executing. In addition to this you see columns for sql_handle and plan_handle. These columns (when combined with other DMO’s we will discuss later) can return the actual sql text that is being executed on your server as well as the actual execution plan that is cached and being used. This DMV also returns information about various wait types that may be occurring for your spid. The percent_complete column displays a percentage to completion for certain database actions such as DBCC CheckDB, Database Restores, Rollback’s, etc. In addition to these, you are also able to see the amount of reads, writes, and cpu that the SPID has consumed. You will find this DMV to be one of the primary DMV’s that you use when looking for information about what is occurring on your server.

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  • Unable to delete duplicate pagefile.sys

    - by user128364
    I have one SQL server that contain two drives on it and both drives are on SAN. C drive contains OS and V drive Contain pagefile.sys file. I rebooted my server and both drives was unmapped on SQL server. Some How one drive came (the OS drive) and created pagefile.sys on C drive and then I rebooted my server remapped the v drive. Now I have two pagefile.sys on C and V drive. But under Advance setting only V drive option is checked as pagefile. How do delete duplicate pagefile on C drive. It showing me that " the program is being used" while deleting the pagefile

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  • Configuring Backup Exec 2012 using USB hard drives as media

    - by SydxPages
    I have found some information on this but have not found the exact answers to these questions. Background I have installed backup exec 2012 (with agents for databases) I have configured a storage pool, with 2 USB drives (1TB) The backups are configured to backup to one of the 2 drives (depending on which one is connected) I have 2 questions: How do I get Backup Exec to tell me which disk to insert? I have used tapes before and it told me then which tape to use? I was hoping this was available for disks too. (Whilst there are only 2 at the moment, there will be more). And then how do I get Backup Exec to delete old backups when the disk if full.

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  • Slow INFORMATION_SCHEMA query

    - by Thomas
    We have a .NET Windows application that runs the following query on login to get some information about the database: SELECT t.TABLE_NAME, ISNULL(pk_ccu.COLUMN_NAME,'') PK, ISNULL(fk_ccu.COLUMN_NAME,'') FK FROM INFORMATION_SCHEMA.TABLES t LEFT JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS pk_tc ON pk_tc.TABLE_NAME = t.TABLE_NAME AND pk_tc.CONSTRAINT_TYPE = 'PRIMARY KEY' LEFT JOIN INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE pk_ccu ON pk_ccu.CONSTRAINT_NAME = pk_tc.CONSTRAINT_NAME LEFT JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS fk_tc ON fk_tc.TABLE_NAME = t.TABLE_NAME AND fk_tc.CONSTRAINT_TYPE = 'FOREIGN KEY' LEFT JOIN INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE fk_ccu ON fk_ccu.CONSTRAINT_NAME = fk_tc.CONSTRAINT_NAME Usually this runs in a couple seconds, but on one server running SQL Server 2000, it is taking over four minutes to run. I ran it with the execution plan enabled, and the results are huge, but this part caught my eye (it won't let me post an image): http://img35.imageshack.us/i/plank.png/ I then updated the statistics on all of the tables that were mentioned in the execution plan: update statistics sysobjects update statistics syscolumns update statistics systypes update statistics master..spt_values update statistics sysreferences But that didn't help. The index tuning wizard doesn't help either, because it doesn't let me select system tables. There is nothing else running on this server, so nothing else could be slowing it down. What else can I do to diagnose or fix the problem on that server?

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  • Backup Exec 12.5 or 2010? [closed]

    - by Chris Thorpe
    Backup Exec 2010 has just dropped, and I'm about to implement a new BEWS infrastructure, complete with CALs and new central servers. When I specced this up last year, I ignored 2010 and focused on Backup Exec 12.5, since it's a mature product. In previous experience, major released of BE had numerous technical issues and seemed to improve significantly at the first service pack. However, our refresh cycle on the backup infrastructure is slow, the main driver usually being lack of support for some new server type (in this case, ESX has driven our current upgrade need). With this in mind, I'm wondering if Backup Exec 2010 should be my first choice, as it'll last longer under current support than 12.5, which will approach EOL soon. Has anyone got any perspective they could add to this? Right now, I'm leaning towards biting the bullet and going with 2010.

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  • Updatable columnstore index, sp_spaceused and sys.partitions

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

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  • Sys.WebForms.PageRequestManagerServerErrorException: An entity object cannot be referenced by multiple instances of IEntityChangeTracker [closed]

    - by Mingebag
    `Story: I have a strange error when I try to save something I got this error message An entity object cannot be referenced by multiple instances of IEntityChangeTracker. I really don’t know what that is and why is it appear, it appears only when I try to save something my insert and update is working, only when I try to save something in db from my Telerik grid if (this.annualVacationList != null) { List<AnnualVacation> vacationToSave = this.annualVacationList; IEnumerable<AnnualVacation> existing = paramUser.AnnualVacations; foreach (AnnualVacation toSave in vacationToSave) { AnnualVacation existingItem = existing.Where(x => x.AnnualVacationId == toSave.AnnualVacationId).SingleOrDefault(); if (existingItem == null) { ctx.AddToAnnualVacations(toSave); } else { existingItem.FromDate = toSave.FromDate; existingItem.ToDate = toSave.ToDate; existingItem.WorkingTime = toSave.WorkingTime; existingItem.VacationDays = toSave.VacationDays; } } } ctx.SaveChanges(); } After debugging I have seen that the code brake down in the Project.Name.Designer.cs ..... O.o public void AddToAnnualVacations(AnnualVacation annualVacation) { base.AddObject("AnnualVacations", annualVacation); }

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  • A quick look at: sys.dm_os_buffer_descriptors

    - by fatherjack
    SQL Server places data into cache as it reads it from disk so as to speed up future queries. This dmv lets you see how much data is cached at any given time and knowing how this changes over time can help you ensure your servers run smoothly and are adequately resourced to run your systems. This dmv gives the number of cached pages in the buffer pool along with the database id that they relate to: USE [tempdb] GO SELECT COUNT(*) AS cached_pages_count , CASE database_id ...(read more)

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  • A quick look at: sys.dm_os_buffer_descriptors

    - by fatherjack
    SQL Server places data into cache as it reads it from disk so as to speed up future queries. This dmv lets you see how much data is cached at any given time and knowing how this changes over time can help you ensure your servers run smoothly and are adequately resourced to run your systems. This dmv gives the number of cached pages in the buffer pool along with the database id that they relate to: USE [tempdb] GO SELECT COUNT(*) AS cached_pages_count , CASE database_id ...(read more)

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  • More CPU cores may not always lead to better performance – MAXDOP and query memory distribution in spotlight

    - by sqlworkshops
    More hardware normally delivers better performance, but there are exceptions where it can hinder performance. Understanding these exceptions and working around it is a major part of SQL Server performance tuning.   When a memory allocating query executes in parallel, SQL Server distributes memory to each task that is executing part of the query in parallel. In our example the sort operator that executes in parallel divides the memory across all tasks assuming even distribution of rows. Common memory allocating queries are that perform Sort and do Hash Match operations like Hash Join or Hash Aggregation or Hash Union.   In reality, how often are column values evenly distributed, think about an example; are employees working for your company distributed evenly across all the Zip codes or mainly concentrated in the headquarters? What happens when you sort result set based on Zip codes? Do all products in the catalog sell equally or are few products hot selling items?   One of my customers tested the below example on a 24 core server with various MAXDOP settings and here are the results:MAXDOP 1: CPU time = 1185 ms, elapsed time = 1188 msMAXDOP 4: CPU time = 1981 ms, elapsed time = 1568 msMAXDOP 8: CPU time = 1918 ms, elapsed time = 1619 msMAXDOP 12: CPU time = 2367 ms, elapsed time = 2258 msMAXDOP 16: CPU time = 2540 ms, elapsed time = 2579 msMAXDOP 20: CPU time = 2470 ms, elapsed time = 2534 msMAXDOP 0: CPU time = 2809 ms, elapsed time = 2721 ms - all 24 cores.In the above test, when the data was evenly distributed, the elapsed time of parallel query was always lower than serial query.   Why does the query get slower and slower with more CPU cores / higher MAXDOP? Maybe you can answer this question after reading the article; let me know: [email protected].   Well you get the point, let’s see an example.   The best way to learn is to practice. To create the below tables and reproduce the behavior, join the mailing list by using this link: www.sqlworkshops.com/ml and I will send you the table creation script.   Let’s update the Employees table with 49 out of 50 employees located in Zip code 2001. update Employees set Zip = EmployeeID / 400 + 1 where EmployeeID % 50 = 1 update Employees set Zip = 2001 where EmployeeID % 50 != 1 go update statistics Employees with fullscan go   Let’s create the temporary table #FireDrill with all possible Zip codes. drop table #FireDrill go create table #FireDrill (Zip int primary key) insert into #FireDrill select distinct Zip from Employees update statistics #FireDrill with fullscan go  Let’s execute the query serially with MAXDOP 1. --Example provided by www.sqlworkshops.com --Execute query with uneven Zip code distribution --First serially with MAXDOP 1 set statistics time on go declare @EmployeeID int, @EmployeeName varchar(48),@zip int select @EmployeeName = e.EmployeeName, @zip = e.Zip from Employees e       inner join #FireDrill fd on (e.Zip = fd.Zip)       order by e.Zip option (maxdop 1) goThe query took 1011 ms to complete.   The execution plan shows the 77816 KB of memory was granted while the estimated rows were 799624.  No Sort Warnings in SQL Server Profiler.  Now let’s execute the query in parallel with MAXDOP 0. --Example provided by www.sqlworkshops.com --Execute query with uneven Zip code distribution --In parallel with MAXDOP 0 set statistics time on go declare @EmployeeID int, @EmployeeName varchar(48),@zip int select @EmployeeName = e.EmployeeName, @zip = e.Zip from Employees e       inner join #FireDrill fd on (e.Zip = fd.Zip)       order by e.Zip option (maxdop 0) go The query took 1912 ms to complete.  The execution plan shows the 79360 KB of memory was granted while the estimated rows were 799624.  The estimated number of rows between serial and parallel plan are the same. The parallel plan has slightly more memory granted due to additional overhead. Sort properties shows the rows are unevenly distributed over the 4 threads.   Sort Warnings in SQL Server Profiler.   Intermediate Summary: The reason for the higher duration with parallel plan was sort spill. This is due to uneven distribution of employees over Zip codes, especially concentration of 49 out of 50 employees in Zip code 2001. Now let’s update the Employees table and distribute employees evenly across all Zip codes.   update Employees set Zip = EmployeeID / 400 + 1 go update statistics Employees with fullscan go  Let’s execute the query serially with MAXDOP 1. --Example provided by www.sqlworkshops.com --Execute query with uneven Zip code distribution --Serially with MAXDOP 1 set statistics time on go declare @EmployeeID int, @EmployeeName varchar(48),@zip int select @EmployeeName = e.EmployeeName, @zip = e.Zip from Employees e       inner join #FireDrill fd on (e.Zip = fd.Zip)       order by e.Zip option (maxdop 1) go   The query took 751 ms to complete.  The execution plan shows the 77816 KB of memory was granted while the estimated rows were 784707.  No Sort Warnings in SQL Server Profiler.   Now let’s execute the query in parallel with MAXDOP 0. --Example provided by www.sqlworkshops.com --Execute query with uneven Zip code distribution --In parallel with MAXDOP 0 set statistics time on go declare @EmployeeID int, @EmployeeName varchar(48),@zip int select @EmployeeName = e.EmployeeName, @zip = e.Zip from Employees e       inner join #FireDrill fd on (e.Zip = fd.Zip)       order by e.Zip option (maxdop 0) go The query took 661 ms to complete.  The execution plan shows the 79360 KB of memory was granted while the estimated rows were 784707.  Sort properties shows the rows are evenly distributed over the 4 threads. No Sort Warnings in SQL Server Profiler.    Intermediate Summary: When employees were distributed unevenly, concentrated on 1 Zip code, parallel sort spilled while serial sort performed well without spilling to tempdb. When the employees were distributed evenly across all Zip codes, parallel sort and serial sort did not spill to tempdb. This shows uneven data distribution may affect the performance of some parallel queries negatively. For detailed discussion of memory allocation, refer to webcasts available at www.sqlworkshops.com/webcasts.     Some of you might conclude from the above execution times that parallel query is not faster even when there is no spill. Below you can see when we are joining limited amount of Zip codes, parallel query will be fasted since it can use Bitmap Filtering.   Let’s update the Employees table with 49 out of 50 employees located in Zip code 2001. update Employees set Zip = EmployeeID / 400 + 1 where EmployeeID % 50 = 1 update Employees set Zip = 2001 where EmployeeID % 50 != 1 go update statistics Employees with fullscan go  Let’s create the temporary table #FireDrill with limited Zip codes. drop table #FireDrill go create table #FireDrill (Zip int primary key) insert into #FireDrill select distinct Zip       from Employees where Zip between 1800 and 2001 update statistics #FireDrill with fullscan go  Let’s execute the query serially with MAXDOP 1. --Example provided by www.sqlworkshops.com --Execute query with uneven Zip code distribution --Serially with MAXDOP 1 set statistics time on go declare @EmployeeID int, @EmployeeName varchar(48),@zip int select @EmployeeName = e.EmployeeName, @zip = e.Zip from Employees e       inner join #FireDrill fd on (e.Zip = fd.Zip)       order by e.Zip option (maxdop 1) go The query took 989 ms to complete.  The execution plan shows the 77816 KB of memory was granted while the estimated rows were 785594. No Sort Warnings in SQL Server Profiler.  Now let’s execute the query in parallel with MAXDOP 0. --Example provided by www.sqlworkshops.com --Execute query with uneven Zip code distribution --In parallel with MAXDOP 0 set statistics time on go declare @EmployeeID int, @EmployeeName varchar(48),@zip int select @EmployeeName = e.EmployeeName, @zip = e.Zip from Employees e       inner join #FireDrill fd on (e.Zip = fd.Zip)       order by e.Zip option (maxdop 0) go The query took 1799 ms to complete.  The execution plan shows the 79360 KB of memory was granted while the estimated rows were 785594.  Sort Warnings in SQL Server Profiler.    The estimated number of rows between serial and parallel plan are the same. The parallel plan has slightly more memory granted due to additional overhead.  Intermediate Summary: The reason for the higher duration with parallel plan even with limited amount of Zip codes was sort spill. This is due to uneven distribution of employees over Zip codes, especially concentration of 49 out of 50 employees in Zip code 2001.   Now let’s update the Employees table and distribute employees evenly across all Zip codes. update Employees set Zip = EmployeeID / 400 + 1 go update statistics Employees with fullscan go Let’s execute the query serially with MAXDOP 1. --Example provided by www.sqlworkshops.com --Execute query with uneven Zip code distribution --Serially with MAXDOP 1 set statistics time on go declare @EmployeeID int, @EmployeeName varchar(48),@zip int select @EmployeeName = e.EmployeeName, @zip = e.Zip from Employees e       inner join #FireDrill fd on (e.Zip = fd.Zip)       order by e.Zip option (maxdop 1) go The query took 250  ms to complete.  The execution plan shows the 9016 KB of memory was granted while the estimated rows were 79973.8.  No Sort Warnings in SQL Server Profiler.  Now let’s execute the query in parallel with MAXDOP 0.  --Example provided by www.sqlworkshops.com --Execute query with uneven Zip code distribution --In parallel with MAXDOP 0 set statistics time on go declare @EmployeeID int, @EmployeeName varchar(48),@zip int select @EmployeeName = e.EmployeeName, @zip = e.Zip from Employees e       inner join #FireDrill fd on (e.Zip = fd.Zip)       order by e.Zip option (maxdop 0) go The query took 85 ms to complete.  The execution plan shows the 13152 KB of memory was granted while the estimated rows were 784707.  No Sort Warnings in SQL Server Profiler.    Here you see, parallel query is much faster than serial query since SQL Server is using Bitmap Filtering to eliminate rows before the hash join.   Parallel queries are very good for performance, but in some cases it can hinder performance. If one identifies the reason for these hindrances, then it is possible to get the best out of parallelism. I covered many aspects of monitoring and tuning parallel queries in webcasts (www.sqlworkshops.com/webcasts) and articles (www.sqlworkshops.com/articles). I suggest you to watch the webcasts and read the articles to better understand how to identify and tune parallel query performance issues.   Summary: One has to avoid sort spill over tempdb and the chances of spills are higher when a query executes in parallel with uneven data distribution. Parallel query brings its own advantage, reduced elapsed time and reduced work with Bitmap Filtering. So it is important to understand how to avoid spills over tempdb and when to execute a query in parallel.   I explain these concepts with detailed examples in my webcasts (www.sqlworkshops.com/webcasts), I recommend you to watch them. The best way to learn is to practice. To create the above tables and reproduce the behavior, join the mailing list at www.sqlworkshops.com/ml and I will send you the relevant SQL Scripts.   Register for the upcoming 3 Day Level 400 Microsoft SQL Server 2008 and SQL Server 2005 Performance Monitoring & Tuning Hands-on Workshop in London, United Kingdom during March 15-17, 2011, click here to register / Microsoft UK TechNet.These are hands-on workshops with a maximum of 12 participants and not lectures. For consulting engagements click here.   Disclaimer and copyright information:This article refers to organizations and products that may be the trademarks or registered trademarks of their various owners. Copyright of this article belongs to R Meyyappan / www.sqlworkshops.com. You may freely use the ideas and concepts discussed in this article with acknowledgement (www.sqlworkshops.com), but you may not claim any of it as your own work. This article is for informational purposes only; you use any of the suggestions given here entirely at your own risk.   Register for the upcoming 3 Day Level 400 Microsoft SQL Server 2008 and SQL Server 2005 Performance Monitoring & Tuning Hands-on Workshop in London, United Kingdom during March 15-17, 2011, click here to register / Microsoft UK TechNet.These are hands-on workshops with a maximum of 12 participants and not lectures. For consulting engagements click here.   R Meyyappan [email protected] LinkedIn: http://at.linkedin.com/in/rmeyyappan  

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  • MySQL Query Select using sub-select takes too long

    - by True Soft
    I noticed something strange while executing a select from 2 tables: SELECT * FROM table_1 WHERE id IN ( SELECT id_element FROM table_2 WHERE column_2=3103); This query took approximatively 242 seconds. But when I executed the subquery SELECT id_element FROM table_2 WHERE column_2=3103 it took less than 0.002s (and resulted 2 rows). Then, when I did SELECT * FROM table_1 WHERE id IN (/* prev.result */) it was the same: 0.002s. I was wondering why MySQL is doing the first query like that, taking much more time than the last 2 queries separately? Is it an optimal solution for selecting something based from the results of a sub-query? Other details: table_1 has approx. 9000 rows, and table_2 has 90000 rows. After I added an index on column_2 from table_2, the first query took 0.15s.

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  • What's wrong with my MySql query ?!

    - by Anytime
    This is a query I am doing with mysql using PHP This is the query line <?php $query = "SELECT * FROM node WHERE type = 'student_report' AND uid = '{$uid}' LIMIT 1 ORDER BY created DESC"; ?> I get the following error You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'ORDER BY created DESC' at line 1

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  • Enthought Canopy - passing sys.argv from PySide Qt program

    - by user2541559
    I've recently been looking at the Enthought distro of iPython. Today I decided to see if I could get some Qt GUI progs running and was successful after making minor changes. Simple example: import sys from PySide import QtGui # was 'from PyQT4 import QtGui' # app = QtGui.QApplication(sys.argv) -- not needed win = QtGui.QWidget() win.resize(320, 240) win.setWindowTitle("Hello MIT 6X!") win.show() sys.exit() # was 'sys.exit(app.exec_())' But I would like to be able to pass sys.argv in some cases. Most example code I see is in the form of the commented out 'app = ' line above. If I include it, I get 'RuntimeError: A QApplication instance already exists.' Suggestions for passing arguments appreciated. Nick

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  • complex sql which runs extremely slow when the query has order by clause

    - by basit.
    I have following complex query which I need to use. When I run it, it takes 30 to 40 seconds. But if I remove the order by clause, it takes 0.0317 sec to return the result, which is really fast compare to 30 sec or 40. select DISTINCT media.* , username from album as album , album_permission as permission , user as user, media as media where ((media.album_id = album.album_id and album.private = 'yes' and album.album_id = permission.album_id and (permission.email = '' or permission.user_id = '') ) or (media.album_id = album.album_id and album.private = 'no' ) or media.album_id = '0' ) and media.user_id = user.user_id and media.media_type = 'video' order by media.id DESC LIMIT 0,20 The id on order by is primary key which is indexed too. So I don't know what is the problem. I also have album and album permission table, just to check if media is public or private, if private then check if user has permission or not. I was thinking maybe that is causing the issue. What if I did this in sub query, would that work better? Also can someone help me write that sub query, if that is the solution? If you can't help write it, just at least tell me. I'm really going crazy with this issue.. SOLUTION MAYBE Yes, I think sub-query would be best solution for this, because the following query runs at 0.0022 seconds. But I'm not sure if validation of an album would be accurate or not, please check. select media.*, username from media as media , user as user where media.user_id = user.user_id and media.media_type = 'video' and media.id in (select media2.id from media as media2 , album as album , album_permission as permission where ((media2.album_id = album.album_id and album.private = 'yes' and album.album_id = permission.album_id and (permission.email = '' or permission.user_id = '')) or (media.album_id = album.album_id and album.private = 'no' ) or media.album_id = '0' ) and media.album_id = media2.album_id ) order by media.id DESC LIMIT 0,20

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  • Specifying a variable name in QUERY WHERE clause in JDBC

    - by Noona
    Could someone please give me a link on how to create a query in JDBC that gets a variable name in the WHERE statement, or write an example, to be more specific, my code looks something like this: private String getLastModified(String url) { String lastModified = null; ResultSet resultSet; String query = "select LastModified from CacheTable where " + " URL.equals(url)"; try { resultSet = sqlStatement.executeQuery(query); } Now I need the syntax that enables me to return a ResultSet object where URL in the cacheTable equals url from the method's argument. thanks

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  • SQL select descendants of a row

    - by Joey Adams
    Suppose a tree structure is implemented in SQL like this: CREATE TABLE nodes ( id INTEGER PRIMARY KEY, parent INTEGER -- references nodes(id) ); Although cycles can be created in this representation, let's assume we never let that happen. The table will only store a collection of roots (records where parent is null) and their descendants. The goal is to, given an id of a node on the table, find all nodes that are descendants of it. A is a descendant of B if either A's parent is B or A's parent is a descendant of B. Note the recursive definition. Here is some sample data: INSERT INTO nodes VALUES (1, NULL); INSERT INTO nodes VALUES (2, 1); INSERT INTO nodes VALUES (3, 2); INSERT INTO nodes VALUES (4, 3); INSERT INTO nodes VALUES (5, 3); INSERT INTO nodes VALUES (6, 2); which represents: 1 `-- 2 |-- 3 | |-- 4 | `-- 5 | `-- 6 We can select the (immediate) children of 1 by doing this: SELECT a.* FROM nodes AS a WHERE parent=1; We can select the children and grandchildren of 1 by doing this: SELECT a.* FROM nodes AS a WHERE parent=1 UNION ALL SELECT b.* FROM nodes AS a, nodes AS b WHERE a.parent=1 AND b.parent=a.id; We can select the children, grandchildren, and great grandchildren of 1 by doing this: SELECT a.* FROM nodes AS a WHERE parent=1 UNION ALL SELECT b.* FROM nodes AS a, nodes AS b WHERE a.parent=1 AND b.parent=a.id UNION ALL SELECT c.* FROM nodes AS a, nodes AS b, nodes AS c WHERE a.parent=1 AND b.parent=a.id AND c.parent=b.id; How can a query be constructed that gets all descendants of node 1 rather than those at a finite depth? It seems like I would need to create a recursive query or something. I'd like to know if such a query would be possible using SQLite. However, if this type of query requires features not available in SQLite, I'm curious to know if it can be done in other SQL databases.

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  • How to call Named Query

    - by sandeep
    I wrote a named query in the entity class Voter NamedQuery(name = "Voter.findvoter", query = "SELECT count(*) FROM Voter v WHERE v.voterID = :voterID" and where v.password= : password), I want to call this named query and I also need to set voterID and password. Can you help me. Thank you

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  • performance issue in a select query from a single table

    - by daedlus
    Hi , I have a table as below dbo.UserLogs ------------------------------------- Id | UserId |Date | Name| P1 | Dirty ------------------------------------- There can be several records per userId[even in millions] I have clustered index on Date column and query this table very frequently in time ranges. The column 'Dirty' is non-nullable and can take either 0 or 1 only so I have no indexes on 'Dirty' I have several millions of records in this table and in one particular case in my application i need to query this table to get all UserId that have at least one record that is marked dirty. I tried this query - select distinct(UserId) from UserLogs where Dirty=1 I have 10 million records in total and this takes like 10min to run and i want this to run much faster than this. [i am able to query this table on date column in less than a minute.] Any comments/suggestion are welcome. my env 64bit,sybase15.0.3,Linux

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  • c# linq to xml dynamic query

    - by David Archer
    Right, bit of a strange question; I have been doing some linq to XML work recently (see my other recent posts here and here). Basically, I want to be able to create a query that checks whether a textbox is null before it's value is included in the query, like so: XDocument db = XDocument.Load(xmlPath); var query = (from vals in db.Descendants("Customer") where (if(textbox1.Text != "") {vals.Element("CustomerID") == Convert.ToInt32(textbox1.Text) } || if(textbox2.Text != "") {vals.Element("Name") == textbox2.Text}) select vals).ToList();

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  • PostgreSQL - Why are some queries on large datasets so incredibly slow

    - by Brad Mathews
    Hello, I have two types of queries I run often on two large datasets. They run much slower than I would expect them to. The first type is a sequential scan updating all records: Update rcra_sites Set street = regexp_replace(street,'/','','i') rcra_sites has 700,000 records. It takes 22 minutes from pgAdmin! I wrote a vb.net function that loops through each record and sends an update query for each record (yes, 700,000 update queries!) and it runs in less than half the time. Hmmm.... The second type is a simple update with a relation and then a sequential scan: Update rcra_sites as sites Set violations='No' From narcra_monitoring as v Where sites.agencyid=v.agencyid and v.found_violation_flag='N' narcra_monitoring has 1,700,000 records. This takes 8 minutes. The query planner refuses to use my indexes. The query runs much faster if I start with a set enable_seqscan = false;. I would prefer if the query planner would do its job. I have appropriate indexes, I have vacuumed and analyzed. I optimized my shared_buffers and effective_cache_size best I know to use more memory since I have 4GB. My hardware is pretty darn good. I am running v8.4 on Windows 7. Is PostgreSQL just this slow? Or am I still missing something? Thanks! Brad

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  • Help me alter this query to get the desired results - New*

    - by sandeepan
    Please dump these data first CREATE TABLE IF NOT EXISTS `all_tag_relations` ( `id_tag_rel` int(10) NOT NULL AUTO_INCREMENT, `id_tag` int(10) unsigned NOT NULL DEFAULT '0', `id_tutor` int(10) DEFAULT NULL, `id_wc` int(10) unsigned DEFAULT NULL, PRIMARY KEY (`id_tag_rel`), KEY `All_Tag_Relations_FKIndex1` (`id_tag`), KEY `id_wc` (`id_wc`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=19 ; INSERT INTO `all_tag_relations` (`id_tag_rel`, `id_tag`, `id_tutor`, `id_wc`) VALUES (1, 1, 1, NULL), (2, 2, 1, NULL), (3, 6, 2, NULL), (4, 7, 2, NULL), (8, 3, 1, 1), (9, 4, 1, 1), (10, 5, 2, 2), (11, 4, 2, 2), (15, 8, 1, 3), (16, 9, 1, 3), (17, 10, 1, 4), (18, 4, 1, 4), (19, 1, 2, 5), (20, 4, 2, 5); 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`), FULLTEXT KEY `tag_5` (`tag`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=11 ; INSERT INTO `tags` (`id_tag`, `tag`) VALUES (1, 'Sandeepan'), (2, 'Nath'), (3, 'first'), (4, 'class'), (5, 'new'), (6, 'Bob'), (7, 'Cratchit'), (8, 'more'), (9, 'fresh'), (10, 'second'); CREATE TABLE IF NOT EXISTS `webclasses` ( `id_wc` int(10) NOT NULL AUTO_INCREMENT, `id_author` int(10) NOT NULL, `name` varchar(50) DEFAULT NULL, PRIMARY KEY (`id_wc`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=5 ; INSERT INTO `webclasses` (`id_wc`, `id_author`, `name`) VALUES (1, 1, 'first class'), (2, 2, 'new class'), (3, 1, 'more fresh'), (4, 1, 'second class'), (5, 2, 'sandeepan class'); About 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. The current data dump corresponds to tutor "Sandeepan Nath" who has created classes named "first class", "more fresh", "second class" and tutor "Bob Cratchit" who has created classes "new class" and "Sandeepan class". I am trying for a search query performs AND logic on the search keywords and returns wvery such class for which the search terms are present in the class name or its tutor name To make it easy, following is the list of search terms and desired results:- Search term result classes (check the id_wc in the results) first class 1 Sandeepan Nath class 1 Sandeepan Nath 1,3 Bob Cratchit 2 Sandeepan Nath bob none Sandeepan Class 1,4,5 I have so far reached upto this query -- Two keywords search SET @tag1 = 4, @tag2 = 1; -- Setting some user variables to see where the ids go. SELECT wc.id_wc, sum( DISTINCT ( wtagrels.id_tag = @tag1 ) ) AS key_1_class_matches, sum( DISTINCT ( wtagrels.id_tag = @tag2 ) ) AS key_2_class_matches, sum( DISTINCT ( ttagrels.id_tag = @tag1 ) ) AS key_1_tutor_matches, sum( DISTINCT ( ttagrels.id_tag = @tag2 ) ) AS key_2_tutor_matches, sum( DISTINCT ( ttagrels.id_tag = wtagrels.id_tag ) ) AS key_class_tutor_matches FROM WebClasses as wc join all_tag_relations AS wtagrels on wc.id_wc = wtagrels.id_wc join all_tag_relations as ttagrels on (wc.id_author = ttagrels.id_tutor) WHERE ( wtagrels.id_tag = @tag1 OR wtagrels.id_tag = @tag2 OR ttagrels.id_tag = @tag1 OR ttagrels.id_tag = @tag2 ) GROUP BY wtagrels.id_wc LIMIT 0 , 20 For search with 1 or 3 terms, remove/add the variable part in this query. Tabulating my observation of the values of key_1_class_matches, key_2_class_matches,key_1_tutor_matches (say, class keys),key_2_tutor_matches for various cases (say, tutor keys). Search term expected result Observation first class 1 for class 1, all class keys+all tutor keys =1 Sandeepan Nath class 1 for class 1, one class key+ all tutor keys = 1 Sandeepan Nath 1,3 both tutor keys =1 for these classes Bob Cratchit 2 both tutor keys = 1 Sandeepan Nath bob none no complete tutor matches for any class I found a pattern that, for any case, the class(es) which should appear in the result have the highest number of matches (all class keys and tutor keys). E.g. searching "first class", only for class =1, total of key matches = 4(1+1+1+1) searching "Sandeepan Nath", for classes 1, 3,4(all classes by Sandeepan Nath) have all the tutor keys matching. But no pattern in the search for "Sandeepan Class" - classes 1,4,5 should match. Now, how do I put a condition into the query, based on that pattern so that only those classes are returned. Do I need to use full text search here because it gives a scoring/rank value indicating the strength of the match? Any sample query would help. Please note - I have already found solution for showing classes when any/all of the search terms match with the class name. http://stackoverflow.com/questions/3030022/mysql-help-me-alter-this-search-query-to-get-desired-results But if all the search terms are in tutor name, it does not work. So, I am modifying the query and experimenting.

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  • Help me alter this query to get the desired results

    - by sandeepan
    Please dump these data first CREATE TABLE IF NOT EXISTS `all_tag_relations` ( `id_tag_rel` int(10) NOT NULL AUTO_INCREMENT, `id_tag` int(10) unsigned NOT NULL DEFAULT '0', `id_tutor` int(10) DEFAULT NULL, `id_wc` int(10) unsigned DEFAULT NULL, PRIMARY KEY (`id_tag_rel`), KEY `All_Tag_Relations_FKIndex1` (`id_tag`), KEY `id_wc` (`id_wc`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=19 ; INSERT INTO `all_tag_relations` (`id_tag_rel`, `id_tag`, `id_tutor`, `id_wc`) VALUES (1, 1, 1, NULL), (2, 2, 1, NULL), (3, 6, 2, NULL), (4, 7, 2, NULL), (8, 3, 1, 1), (9, 4, 1, 1), (10, 5, 2, 2), (11, 4, 2, 2), (15, 8, 1, 3), (16, 9, 1, 3), (17, 10, 1, 4), (18, 4, 1, 4), (19, 1, 2, 5), (20, 4, 2, 5); 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`), FULLTEXT KEY `tag_5` (`tag`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=11 ; INSERT INTO `tags` (`id_tag`, `tag`) VALUES (1, 'Sandeepan'), (2, 'Nath'), (3, 'first'), (4, 'class'), (5, 'new'), (6, 'Bob'), (7, 'Cratchit'), (8, 'more'), (9, 'fresh'), (10, 'second'); CREATE TABLE IF NOT EXISTS `webclasses` ( `id_wc` int(10) NOT NULL AUTO_INCREMENT, `id_author` int(10) NOT NULL, `name` varchar(50) DEFAULT NULL, PRIMARY KEY (`id_wc`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=5 ; INSERT INTO `webclasses` (`id_wc`, `id_author`, `name`) VALUES (1, 1, 'first class'), (2, 2, 'new class'), (3, 1, 'more fresh'), (4, 1, 'second class'), (5, 2, 'sandeepan class'); About 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. The current data dump corresponds to tutor "Sandeepan Nath" who has created classes named "first class", "more fresh", "second class" and tutor "Bob Cratchit" who has created classes "new class" and "Sandeepan class". I am trying for a search query performs AND logic on the search keywords and returns wvery such class for which the search terms are present in the class name or its tutor name To make it easy, following is the list of search terms and desired results:- Search term result classes (check the id_wc in the results) first class 1 Sandeepan Nath class 1 Sandeepan Nath 1,3 Bob Cratchit 2 Sandeepan Nath bob none Sandeepan Class 1,4,5 I have so far reached upto this query -- Two keywords search SET @tag1 = 4, @tag2 = 1; -- Setting some user variables to see where the ids go. SELECT wc.id_wc, sum( DISTINCT ( wtagrels.id_tag = @tag1 ) ) AS key_1_class_matches, sum( DISTINCT ( wtagrels.id_tag = @tag2 ) ) AS key_2_class_matches, sum( DISTINCT ( ttagrels.id_tag = @tag1 ) ) AS key_1_tutor_matches, sum( DISTINCT ( ttagrels.id_tag = @tag2 ) ) AS key_2_tutor_matches, sum( DISTINCT ( ttagrels.id_tag = wtagrels.id_tag ) ) AS key_class_tutor_matches FROM WebClasses as wc join all_tag_relations AS wtagrels on wc.id_wc = wtagrels.id_wc join all_tag_relations as ttagrels on (wc.id_author = ttagrels.id_tutor) WHERE ( wtagrels.id_tag = @tag1 OR wtagrels.id_tag = @tag2 OR ttagrels.id_tag = @tag1 OR ttagrels.id_tag = @tag2 ) GROUP BY wtagrels.id_wc LIMIT 0 , 20 For search with 1 or 3 terms, remove/add the variable part in this query. Tabulating my observation of the values of key_1_class_matches, key_2_class_matches,key_1_tutor_matches (say, class keys),key_2_tutor_matches for various cases (say, tutor keys). Search term expected result Observation first class 1 for class 1, all class keys+all tutor keys =1 Sandeepan Nath class 1 for class 1, one class key+ all tutor keys = 1 Sandeepan Nath 1,3 both tutor keys =1 for these classes Bob Cratchit 2 both tutor keys = 1 Sandeepan Nath bob none no complete tutor matches for any class I found a pattern that, for any case, the class(es) which should appear in the result have the highest number of matches (all class keys and tutor keys). E.g. searching "first class", only for class =1, total of key matches = 4(1+1+1+1) searching "Sandeepan Nath", for classes 1, 3,4(all classes by Sandeepan Nath) have all the tutor keys matching. But no pattern in the search for "Sandeepan Class" - classes 1,4,5 should match. Now, how do I put a condition into the query, based on that pattern so that only those classes are returned. Do I need to use full text search here because it gives a scoring/rank value indicating the strength of the match? Any sample query would help. Please note - I have already found solution for showing classes when any/all of the search terms match with the class name. http://stackoverflow.com/questions/3030022/mysql-help-me-alter-this-search-query-to-get-desired-results But if all the search terms are in tutor name, it does not work. So, I am modifying the query and experimenting.

    Read the article

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