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• Does Your Business Really Need a Search Engine Optimization Specialist?

  If you're an individual or an organization planning to employ a search engine optimization professional, you might first want to consider the possibility of doing this work yourself. Certainly, a search engine optimization consultant can boost your site and perhaps help save you time and effort, yet the fact is that SEO is hardly an advanced science, and there are just a handful of authentic professionals within the field. So, if you depend on somebody else to be in charge of your search engine optimization, there's a high probability that the person will not possess a great deal more knowledge than you. And if you lack any knowledge, all the relevant information is easy to obtain.

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• mysql index optimization for a table with multiple indexes that index some of the same columns

  - by Sean

  I have a table that stores some basic data about visitor sessions on third party web sites. This is its structure: id, site_id, unixtime, unixtime_last, ip_address, uid There are four indexes: id, site_id/unixtime, site_id/ip_address, and site_id/uid There are many different types of ways that we query this table, and all of them are specific to the site_id. The index with unixtime is used to display the list of visitors for a given date or time range. The other two are used to find all visits from an IP address or a "uid" (a unique cookie value created for each visitor), as well as determining if this is a new visitor or a returning visitor. Obviously storing site_id inside 3 indexes is inefficient for both write speed and storage, but I see no way around it, since I need to be able to quickly query this data for a given specific site_id. Any ideas on making this more efficient? I don't really understand B-trees besides some very basic stuff, but it's more efficient to have the left-most column of an index be the one with the least variance - correct? Because I considered having the site_id being the second column of the index for both ip_address and uid but I think that would make the index less efficient since the IP and UID are going to vary more than the site ID will, because we only have about 8000 unique sites per database server, but millions of unique visitors across all ~8000 sites on a daily basis. I've also considered removing site_id from the IP and UID indexes completely, since the chances of the same visitor going to multiple sites that share the same database server are quite small, but in cases where this does happen, I fear it could be quite slow to determine if this is a new visitor to this site_id or not. The query would be something like: select id from sessions where uid = 'value' and site_id = 123 limit 1 ... so if this visitor had visited this site before, it would only need to find one row with this site_id before it stopped. This wouldn't be super fast necessarily, but acceptably fast. But say we have a site that gets 500,000 visitors a day, and a particular visitor loves this site and goes there 10 times a day. Now they happen to hit another site on the same database server for the first time. The above query could take quite a long time to search through all of the potentially thousands of rows for this UID, scattered all over the disk, since it wouldn't be finding one for this site ID. Any insight on making this as efficient as possible would be appreciated :) Update - this is a MyISAM table with MySQL 5.0. My concerns are both with performance as well as storage space. This table is both read and write heavy. If I had to choose between performance and storage, my biggest concern is performance - but both are important. We use memcached heavily in all areas of our service, but that's not an excuse to not care about the database design. I want the database to be as efficient as possible.

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• NotSupportedException on IQuery's Enumerable when using statelesssession

  - by user57555

  when trying to use the Enumerable method on a named query, with a Stateless session, as shown in the example at: http://www.nhforge.org/doc/nh/en/#batch-statelesssession i am seeing a NotSupportedException. the stack trace is as below: System.NotSupportedException: Specified method is not supported. at NHibernate.Impl.StatelessSessionImpl.Enumerable(String query, QueryParameters parameters) at NHibernate.Impl.QueryImpl.Enumerable() here is a snippet of my code: IStatelessSession statelessSession = sessionFactory.OpenStatelessSession(); var fileLines = statelessSession.GetNamedQuery("GetLinesByFileId") .SetInt32("FileIdInput", fileId).Enumerable<FileLineEntity>(); the named query, GetLinesByFileId is defined in the hbm as below: <query name="GetLinesByFileId" cacheable="false" read-only="true"> <![CDATA[ from FileLineEntity lineItem where lineItem.FileId=:FileIdInput ]]> </query> any suggestions on what i maybe missing here?

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• mysql partitioning

  - by Yang

  just want to verify that database partition is implemented only at the database level, when we query a partitioned table, we still do our normal query, nothing special with our queries, the optimization is performed automatically when parsing the query, is that correct? e.g. we have a table called 'address' with a column called 'country_code' and 'city'. so if i want to get all the addresses in New York, US, normally i wound do something like this: select * from address where country_code = 'US' and city = 'New York' if now the table is partitioned by 'country_code', and i know that now the query will only be executed on the partition which contains country_code = US. My question is do I need to explicitly specify the partition to query in my sql statement? or i still use the previous statement and the db server will optimize it automatically? Thanks in advance!

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• Why does Sql Server recommends creating an index when it already exist?

  - by Pierre-Alain Vigeant

  I ran a very basic query against one of our table and I noticed that the execution plan query processor is recommending that we create an index on a column The query is SELECT SUM(DATALENGTH(Data)) FROM Item WHERE Namespace = 'http://some_url/some_namespace/' After running, I get the following message // The Query Processor estimates that implementing the following index could improve the query cost by 96.7211%. CREATE NONCLUSTERED INDEX [<Name of Missing Index, sysname,>] ON [dbo].[Item] ([Namespace]) My problem is that I already have such index on that column: CREATE NONCLUSTERED INDEX [IX_ItemNamespace] ON [dbo].[Item] ( [Namespace] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] Why is Sql Server recommending me to create such index when it already exist?

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• MySQL parameter resource error

  - by Derek

  Here is my error: Warning: mysql_query() expects parameter 2 to be resource, null given... This refers to line 23 of my code which is: $result = mysql_query($sql, $connection) My entire query code looks like this: $query = "SELECT * from users WHERE userid='".intval( $_SESSION['SESS_USERID'] )."'"; $result = mysql_query($query, $connection) or die ("Couldn't perform query $query <br />".mysql_error()); $row = mysql_fetch_array($result); I don't have a clue what has happpened here. All I wanted to do was to have the value of the users 'fullname' displayed in the header section of my web page. So I am outputting this code immediately after to try and achieve this: echo 'Hello '; echo $row['fullname']; Before this change, I had it working perfectly, where the session variable of fullname was echoed $_SESSION['SESS_NAME']. However, because my user can update their information (including their name), I wanted the name displayed in the header to be updated accordingly, and not displaying the session value.

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• Mysql - Grouping the result based on a mathematical operation and SUM() function

  - by SpikETidE

  Hi all... I'm having the following two tables... Table : room_type type_id type_name no_of_rooms max_guests rate 1 Type 1 15 2 1254 2 Type 2 10 1 3025 Table : reservation reservation_id start_date end_date room_type booked_rooms 1 2010-04-12 2010-04-15 1 8 2 2010-04-12 2010-04-15 1 2 Now... I have this query SELECT type_id, type_name FROM room_type WHERE id NOT IN (SELECT room_type FROM reservation WHERE start_date >= '$start_date' AND end_date <= '$end_date') What the query does is it selects the rooms that are not booked between the start date and end date. Also, as you can see from the reservation table, we also have 'number of rooms booked between the two dates' factor also... I need to add this 'no.of booked rooms between the two dates' factor also in to the query... The query should return the type of rooms for which at least one room is free between the two dates. I worked out the logic but just can't represent it as a query....! How will you do this...? Thanks for your suggestions..!

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• Which index is used in select and why?

  - by Lukasz Lysik

  I have the table with zip codes with following columns: id - PRIMARY KEY code - NONCLUSTERED INDEX city When I execute query SELECT TOP 10 * FROM ZIPCodes I get the results sorted by id column. But when I change the query to: SELECT TOP 10 id FROM ZIPCodes I get the results sorted by code column. Again, when I change the query to: SELECT TOP 10 code FROM ZIPCodes I get the results sorted by code column again. And finally when I change to: SELECT TOP 10 id,code FROM ZIPCodes I get the results sorted by id column. My question is in the title of the question. I know which indexes are used in the queries, but my question is, why those indexes are used? I the second query (SELECT TOP 10 id FROM ZIPCodes) wouldn't it be faster if the clusteder index was used? How the query engine chooses which index to use?

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• mysql - check if data exists across multiple tables

  - by Dd Daym

  I am currently running this query inside MySQL to check if the specified values exists within the table associated with them. SELECT COUNT(artist.artist_id), COUNT(album.album_id), COUNT(tracks.track_id) FROM artist, album, tracks WHERE artist.artist_id = 320295 OR album.album_id = 1234 OR tracks.track_id = 809 The result I get from running this query is all 1, meaning that all the statements after the WHERE clause is true. To further check the query's reliability, I changed the tracks.track_ = 809 to 802, which I know does not match. However the results displayed are still all 1, meaning that they were all successfully matched even when I purposefully inserted a value which would not have matched. How do I get it to show 1 for a match and 0 for no matches within the same query? EDIT: I have inserted an image of the query running

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• MySQL - Counting rows in preparation for greatest-n-per-group not working?

  - by John M

  Referring to SO and other sites have given me examples of how to use MySQL to create a 'greatest-n-per-group' query. My variant on this would be to have a query that returns the first 3 rows of each category. As the basis for this I need to sort my data into a usable sequence and that is where my problems start. Running just the sequence query with row numbering shows that changes in category are mostly ignored. I should have 35 categories returning rows but only 5 do so. My query: set @c:=0; set @a:=0; SELECT IF(@c = tdg, @a:=@a+1, @a:=1) AS rownum, (@c:=tdg) , julian_day, sequence, complete, year, tdg FROM tsd WHERE complete = 0 order by tdg, year, julian_day, sequence Do I have a syntax mistake with this query?

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• Performance problems when running Java desktop applications on Citrix Metaframe

  - by demetriusnunes

  We have a desktop Java application running within a Citrix Metaframe server farm and the performance, specially while starting up the app, is very unreliable. Sometimes it takes 15 seconds and sometimes it takes over a minute. It's really unpredicatable. Is there any way to optimize running Java desktop applications within Citrix Metaframe Terminal server sessions to a more reliable performance level? Are there any optimization directed specifically toward Java, such as pre-load JVMs or something like that? Any help would be greatly appreciated.

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• Options to optimize lotus notes 8.5.X

  - by Jakub

  Has anyone found actually useful optimization methods for the bulky, fat, eclipse giant, nuissance that is Lotus Notes 8.5? I want it to be fast, and not eat up system resources like crazy while I run it ALL day (as it is my company's corporate mail / cal / scheduling solution). I've tried various hacks for the JVM heap size (if I recall correctly). None really bring a performance improvement. I have a dual core cpu, if that helps (I tried going the route of optimizing JAVA for 2 cores in hopes it would work, but seen no speed improvement). Notes is just sooo bloated, anyone have any suggestions to optimize/mod this thing so it is more responsive and less of a resource hog. Note: I don't want to switch to the web version, or the standard stripped down versions, I am aware of those, I just cannot since we don't run those internally for the company.

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• Fusion 3.1 and Parallels 6 for Win7 x64

  - by Ronnie

  I read in a recent article that Parallels Desktop 6 is faster almost everywhere than VMware Fusion. I was originally using Parallels 4 before passing to VMware due to the frequent Parallels crashes. As now I am using a lot Fusion on my Macbook on a big Win7 x64 virtualized development machine that I find too slow I am wondering if the announced speed up of Parallels V6 is justified to come back to it. As a test I converted my Fusion 3.1 to a trial of Parallels Desktop 6 and my Windows Experience Index passed from 4.7 of Fusion to 4.5 on Parallels 6 so apparently the virtualized machine is not seeing that speed benefit. Is there any optimization to set up on Parallels to increase the WEI or should I stay with Fusion (and in this case this kind of articles is just marketing stuff)?

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• Does anyone still use Iometer?

  - by Brian T Hannan

  "Iometer is an I/O subsystem measurement and characterization tool for single and clustered systems. It is used as a benchmark and troubleshooting tool and is easily configured to replicate the behaviour of many popular applications." link text Does anyone still use this tool? It seems helpful, but I'm not sure if it's for the thing I am trying to work on. I am trying create a benchmark computer performance test that can be run before and after a Windows Optimization program does its stuff (ex: PC Optimizer Pro or CCleaner). I want to be able to make a quick statement like CCleaner makes the computer run 50% faster or something along those lines. Are there any newer tools like this one?

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• MysqlTunner and query_cache_size dilemma

  - by wbad

  On a busy mysql server MySQLTuner 1.2.0 always recommends to add query_cache_size no matter how I increase the value (I tried up to 512MB). On the other hand it warns that : Increasing the query_cache size over 128M may reduce performance Here are the last results: >> MySQLTuner 1.2.0 - Major Hayden <[email protected]> >> Bug reports, feature requests, and downloads at http://mysqltuner.com/ >> Run with '--help' for additional options and output filtering -------- General Statistics -------------------------------------------------- [--] Skipped version check for MySQLTuner script [OK] Currently running supported MySQL version 5.5.25-1~dotdeb.0-log [OK] Operating on 64-bit architecture -------- Storage Engine Statistics ------------------------------------------- [--] Status: +Archive -BDB -Federated +InnoDB -ISAM -NDBCluster [--] Data in InnoDB tables: 6G (Tables: 195) [--] Data in PERFORMANCE_SCHEMA tables: 0B (Tables: 17) [!!] Total fragmented tables: 51 -------- Security Recommendations ------------------------------------------- [OK] All database users have passwords assigned -------- Performance Metrics ------------------------------------------------- [--] Up for: 1d 19h 17m 8s (254M q [1K qps], 5M conn, TX: 139B, RX: 32B) [--] Reads / Writes: 89% / 11% [--] Total buffers: 24.2G global + 92.2M per thread (1200 max threads) [!!] Maximum possible memory usage: 132.2G (139% of installed RAM) [OK] Slow queries: 0% (2K/254M) [OK] Highest usage of available connections: 32% (391/1200) [OK] Key buffer size / total MyISAM indexes: 128.0M/92.0K [OK] Key buffer hit rate: 100.0% (8B cached / 0 reads) [OK] Query cache efficiency: 79.9% (181M cached / 226M selects) [!!] Query cache prunes per day: 1033203 [OK] Sorts requiring temporary tables: 0% (341 temp sorts / 4M sorts) [OK] Temporary tables created on disk: 14% (760K on disk / 5M total) [OK] Thread cache hit rate: 99% (676 created / 5M connections) [OK] Table cache hit rate: 22% (1K open / 8K opened) [OK] Open file limit used: 0% (49/13K) [OK] Table locks acquired immediately: 99% (64M immediate / 64M locks) [OK] InnoDB data size / buffer pool: 6.1G/19.5G -------- Recommendations ----------------------------------------------------- General recommendations: Run OPTIMIZE TABLE to defragment tables for better performance Reduce your overall MySQL memory footprint for system stability Increasing the query_cache size over 128M may reduce performance Variables to adjust: *** MySQL's maximum memory usage is dangerously high *** *** Add RAM before increasing MySQL buffer variables *** query_cache_size (> 192M) [see warning above] The server has 76GB ram and dual E5-2650. The load is usually below 2. I appreciate your hints to interpret the recommendation and optimize the database configs.

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• Access 2007 VBA & SQL - Update a Subform pointed at a dynamically created query

  - by Lucretius

  Abstract: I'm using VB to recreate a query each time a user selects one of 3 options from a drop down menu, which appends the WHERE clause If they've selected anything from the combo boxes. I then am attempting to get the information displayed on the form to refresh thereby filtering what is displayed in the table based on user input. 1) Dynamically created query using VB. Private Sub BuildQuery() ' This sub routine will redefine the subQryAllJobsQuery based on input from ' the user on the Management tab. Dim strQryName As String Dim strSql As String ' Main SQL SELECT statement Dim strWhere As String ' Optional WHERE clause Dim qryDef As DAO.QueryDef Dim dbs As DAO.Database strQryName = "qryAllOpenJobs" strSql = "SELECT * FROM tblOpenJobs" Set dbs = CurrentDb ' In case the query already exists we should deleted it ' so that we can rebuild it. The ObjectExists() function ' calls a public function in GlobalVariables module. If ObjectExists("Query", strQryName) Then DoCmd.DeleteObject acQuery, strQryName End If ' Check to see if anything was selected from the Shift ' Drop down menu. If so, begin the where clause. If Not IsNull(Me.cboShift.Value) Then strWhere = "WHERE tblOpenJobs.[Shift] = '" & Me.cboShift.Value & "'" End If ' Check to see if anything was selected from the Department ' drop down menu. If so, append or begin the where clause. If Not IsNull(Me.cboDepartment.Value) Then If IsNull(strWhere) Then strWhere = strWhere & " AND tblOpenJobs.[Department] = '" & Me.cboDepartment.Value & "'" Else strWhere = "WHERE tblOpenJobs.[Department] = '" & Me.cboDepartment.Value & "'" End If End If ' Check to see if anything was selected from the Date ' field. If so, append or begin the Where clause. If Not IsNull(Me.txtDate.Value) Then If Not IsNull(strWhere) Then strWhere = strWhere & " AND tblOpenJobs.[Date] = '" & Me.txtDate.Value & "'" Else strWhere = "WHERE tblOpenJobs.[Date] = '" & Me.txtDate.Value & "'" End If End If ' Concatenate the Select and the Where clause together ' unless all three parameters are null, in which case return ' just the plain select statement. If IsNull(Me.cboShift.Value) And IsNull(Me.cboDepartment.Value) And IsNull(Me.txtDate.Value) Then Set qryDef = dbs.CreateQueryDef(strQryName, strSql) Else strSql = strSql & " " & strWhere Set qryDef = dbs.CreateQueryDef(strQryName, strSql) End If End Sub 2) Main Form where the user selects items from combo boxes. picture of the main form and sub form http://i48.tinypic.com/25pjw2a.png 3) Subform pointed at the query created in step 1. Chain of events: 1) User selects item from drop down list on the main form. 2) Old query is deleted, new query is generated (same name). 3) Subform pointed at query does not update, but if you open the query by itself the correct results are displayed. Name of the Query: qryAllOpenJobs name of the subform: subQryAllOpenJobs Also, the Row Source of subQryAllOpenJobs = qryAllOpenJobs Name of the main form: frmManagement

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• C++ MySQL++ Delete query statement brain killer question

  - by shauny

  Hello all, I'm relatively new to the MySQL++ connector in C++, and have an really annoying issue with it already! I've managed to get stored procedures working, however i'm having issues with the delete statements. I've looked high and low and have found no documentation with examples. First I thought maybe the code needs to free the query/connection results after calling the stored procedure, but of course MySQL++ doesn't have a free_result method... or does it? Anyways, here's what I've got: #include <iostream> #include <stdio.h> #include <queue> #include <deque> #include <sys/stat.h> #include <mysql++/mysql++.h> #include <boost/thread/thread.hpp> #include "RepositoryQueue.h" using namespace boost; using namespace mysqlpp; class RepositoryChecker { private: bool _isRunning; Connection _con; public: RepositoryChecker() { try { this->_con = Connection(false); this->_con.set_option(new MultiStatementsOption(true)); this->_con.set_option(new ReconnectOption(true)); this->_con.connect("**", "***", "***", "***"); this->ChangeRunningState(true); } catch(const Exception& e) { this->ChangeRunningState(false); } } /** * Thread method which runs and creates the repositories */ void CheckRepositoryQueues() { //while(this->IsRunning()) //{ std::queue<RepositoryQueue> queues = this->GetQueue(); if(queues.size() > 0) { while(!queues.empty()) { RepositoryQueue &q = queues.front(); char cmd[256]; sprintf(cmd, "svnadmin create /home/svn/%s/%s/%s", q.GetPublicStatus().c_str(), q.GetUsername().c_str(), q.GetRepositoryName().c_str()); if(this->DeleteQueuedRepository(q.GetQueueId())) { printf("query deleted?\n"); } printf("Repository created!\n"); queues.pop(); } } boost::this_thread::sleep(boost::posix_time::milliseconds(500)); //} } protected: /** * Gets the latest queue of repositories from the database * and returns them inside a cool queue defined with the * RepositoryQueue class. */ std::queue<RepositoryQueue> GetQueue() { std::queue<RepositoryQueue> queues; Query query = this->_con.query("CALL sp_GetRepositoryQueue();"); StoreQueryResult result = query.store(); RepositoryQueue rQ; if(result.num_rows() > 0) { for(unsigned int i = 0;i < result.num_rows(); ++i) { rQ = RepositoryQueue((unsigned int)result[i][0], (unsigned int)result[i][1], (String)result[i][2], (String)result[i][3], (String)result[i][4], (bool)result[i][5]); queues.push(rQ); } } return queues; } /** * Allows the thread to be shut off. */ void ChangeRunningState(bool isRunning) { this->_isRunning = isRunning; } /** * Returns the running value of the active thread. */ bool IsRunning() { return this->_isRunning; } /** * Deletes the repository from the mysql queue table. This is * only called once it has been created. */ bool DeleteQueuedRepository(unsigned int id) { char cmd[256]; sprintf(cmd, "DELETE FROM RepositoryQueue WHERE Id = %d LIMIT 1;", id); Query query = this->_con.query(cmd); return (query.exec()); } }; I've removed all the other methods as they're not needed... Basically it's the DeleteQueuedRepository method which isn't working, the GetQueue works fine. PS: This is on a Linux OS (Ubuntu server) Many thanks, Shaun

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• Problem with PHP/AS3 - Display PHP query results back to flash via AS3

  - by Dale J

  Hi, Ive made a query in PHP, and i'm trying to send the results back into Flash via AS3, but its throwing up this error Error: Error #2101: The String passed to URLVariables.decode() must be a URL-encoded query string containing name/value pairs. at Error$/throwError() at flash.net::URLVariables/decode() at flash.net::URLVariables() at flash.net::URLLoader/onComplete() Here is the relevant part of the PHP and AS3 code, including the query. The flash variable rssAdd is passed over to the PHP which it using it in the PHP query accordingly. $url = $_POST['rssAdd']; $query= SELECT title FROM Feed WHERE category = (SELECT category FROM Feed WHERE url =$url) AND url!=$url; $result = mysql_query($query); echo $query; Here is the AS3 code I've done so far. function recommendation(){ var request:URLRequest = new URLRequest("url"); request.method = URLRequestMethod.POST var recVars:URLVariables = new URLVariables(); recVars.rssAdd=rssAdd; request.data = recVars var loader:URLLoader = new URLLoader(request); loader.addEventListener(Event.COMPLETE, onComplete); loader.dataFormat = URLLoaderDataFormat.TEXT; loader.load(request); function onComplete(event:Event):void{ recommend.text = event.target.data; } } Any help would be most appreciated, thanks.

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• SQL 2005 indexed queries slower than unindexed queries

  - by uos??

  Adding a seemingly perfectly index is having an unexpectedly adverse affect on a query performance... -- [Data] has a predictable structure and a simple clustered index of the primary key: ALTER TABLE [dbo].[Data] ADD PRIMARY KEY CLUSTERED ( [ID] ) -- My query, joins on itself looking for a certain kind of "overlapping" records SELECT DISTINCT [Data].ID AS [ID] FROM dbo.[Data] AS [Data] JOIN dbo.[Data] AS [Compared] ON [Data].[A] = [Compared].[A] AND [Data].[B] = [Compared].[B] AND [Data].[C] = [Compared].[C] AND ([Data].[D] = [Compared].[D] OR [Data].[E] = [Compared].[E]) AND [Data].[F] <> [Compared].[F] WHERE 1=1 AND [Data].[A] = @A AND @CS <= [Data].[C] AND [Data].[C] < @CE -- Between a range [Data] has about a quarter-million records so far, 10% to 50% of the data satisfies the where clause depending on @A, @CS, and @CE. As is, the query takes 1 second to return about 300 rows when querying 10%, and 30 seconds to return 3000 rows when querying 50% of the data. Curiously, the estimated/actual execution plan indicates two parallel Clustered Index Scans, but the clustered index is only of the ID, which isn't part of the conditions of the query, only the output. ?? If I add this hand-crafted [IDX_A_B_C_D_E_F] index which I fully expected to improve performance, the query slows down by a factor of 8 (8 seconds for 10% & 4 minutes for 50%). The estimated/actual execution plans show an Index Seek, which seems like the right thing to be doing, but why so slow?? CREATE UNIQUE INDEX [IDX_A_B_C_D_E_F] ON [dbo].[Data] ([A], [B], [C], [D], [E], [F]) INCLUDE ([ID], [X], [Y], [Z]); The Data Engine Tuning wizard suggests a similar index with no noticeable difference in performance from this one. Moving AND [Data].[F] <> [Compared].[F] from the join condition to the where clause makes no difference in performance. I need these and other indexes for other queries. I'm sure I could hint that the query should refer to the Clustered Index, since that's currently winning - but we all know it is not as optimized as it could be, and without a proper index, I can expect the performance will get much worse with additional data. What gives?

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• SQL Where Clause Against View

  - by Adam Carr

  I have a view (actually, it's a table valued function, but the observed behavior is the same in both) that inner joins and left outer joins several other tables. When I query this view with a where clause similar to SELECT * FROM [v_MyView] WHERE [Name] like '%Doe, John%' ... the query is very slow, but if I do the following... SELECT * FROM [v_MyView] WHERE [ID] in ( SELECT [ID] FROM [v_MyView] WHERE [Name] like '%Doe, John%' ) it is MUCH faster. The first query is taking at least 2 minutes to return, if not longer where the second query will return in less than 5 seconds. Any suggestions on how I can improve this? If I run the whole command as one SQL statement (without the use of a view) it is very fast as well. I believe this result is because of how a view should behave as a table in that if a view has OUTER JOINS, GROUP BYS or TOP ##, if the where clause was interpreted prior to vs after the execution of the view, the results could differ. My question is why wouldn't SQL optimize my first query to something as efficient as my second query?

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• My SQL query is only returning I need the parent aswell

  - by sico87

  My sql query is only returning the children of the parent I need it to return the parent as well, public function getNav($cat,$subcat){ //gets all sub categories for a specific category if(!$this->checkValue($cat)) return false; //checks data $query = false; if($cat=='NULL'){ $sql = "SELECT itemID, title, parent, url, description, image FROM p_cat WHERE deleted = 0 AND parent is NULL ORDER BY position;"; $query = $this->db->query($sql) or die($this->db->error); }else{ //die($cat); $sql = "SET @parent = (SELECT c.itemID FROM p_cat c WHERE url = '".$this->sql($cat)."' AND deleted = 0); SELECT c1.itemID, c1.title, c1.parent, c1.url, c1.description, c1.image, (SELECT c2.url FROM p_cat c2 WHERE c2.itemID = c1.parent LIMIT 1) as parentUrl FROM p_cat c1 WHERE c1.deleted = 0 AND c1.parent = @parent ORDER BY c1.position;"; $query = $this->db->multi_query($sql) or die($this->db->error); $this->db->store_result(); $this->db->next_result(); $query = $this->db->store_result(); } return $query; }

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• Searching For A Record After A LINQ query

  - by Justin

  I'm confused to why this is happening. I'm new to LINQ so I'm clearly missing something here, that is probably pretty easy. I've looked up help on the topic, but I don't really know what to ask so I haven't found any answers that really address my question. This doesn't work It throws an EntityCommandExecutionException when the FirstOrDefault method is executed. var query = from band in context.BandsEntitySet where band.ID == 12345 select band; string venueName = "Willis Park"; foreach (var item in query) { var venue = context.VenueEntitySet.FirstOrDefault(r => r.Venue.Equals(venueName)); } This works var query = from band in context.BandsEntitySet where band.ID == 12345 select band; var bandList = query.toList(); string venueName = "Willis Park"; foreach (var item in bandList) { var venue = context.VenueEntitySet.FirstOrDefault(r => r.Venue.Equals(venueName)); } My question is simple: Why is the exception being thrown? And why does creating a list from the query allow me to use the FirstOrDefault method? Exception Message: A first chance exception of type 'System.Data.EntityCommandExecutionException' occurred in System.Data.Entity.dll I guess I am wrong in my assumption that query is a list? Then what is it exactly? I'm confused because this doesn't throw an exception: foreach (var item in query) { var area = item.VenueArea; } I'd appreciate any help on this issue. thanks, Justin

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• How to query the SPView object

  - by Hugo Migneron

  I have a SPView object that contains a lot of SPListItem objects (there are many fields in the view). I am only interested in one of these fields. Let's call it specialField Given that view and specialField, I want to know if a value is contained in specialField. Here is a way of doing what I want to do : String specialField = "Special Field"; String specialValue = "value"; SPList list = SPContext.Current.Site.RootWeb.Lists["My List"]; SPView view = list.Views["My View"]; //This is the view I want to query SPQuery query = new SPQuery(); query.Query = view.Query; SPListItemCollection items = list.GetItems(query); foreach(SPListItem item in items) { var value = item[specialField]; if(value != null) && (value.ToString() == specialValue) { //My value is found. This is what I was looking for. //break out of the loop or return } } //My value is not found. However, iterating through each ListItem hardly seems optimal, especially as there might be hundreds of items. This query will be executed often, so I am looking for an efficient way to do this. EDIT I will not always be working with the same view, so my solution cannot be hardcoded (it has to be generic enough that the list, view and specialField can be changed.

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• Slow T-SQL query, convert to LINQ to Object

  - by yimbot

  I have a T-SQL query which populates a DataSet from an MSSQL database. string qry = "SELECT * FROM EvnLog AS E WHERE TimeDate = (SELECT MAX(TimeDate) From EvnLog WHERE Code = E.Code) AND (Event = 8) AND (TimeDate BETWEEN '" + Start + "' AND '" + Finish + "')" The database is quite large and being the type of nested query it is, the Data Adapter can take a number of minutes to fill the DataSet. I have extended the DataAdapter's timeout value to 480 seconds to combat it, but the client still complains about slow performance and occassional timeouts. To combat this, I was considering executing a simpler query (ie. just taking the date range) and then populating a Generic List which I could then execute a Linq query against. The simple query executes very quickly which is great. However, I cannot seem to build a Linq query which generates the same results as the T-SQL query above. Is this the best solution to this problem? Can anyone provide tips on rewriting the above T-SQL into Linq? I have also considered using a DataView, but cannot seem to get the results from that either.

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• How To perform a SQL Query to DataTable Operation That Can Be Cancelled

  - by David W

  I tried to make the title as specific as possible. Basically what I have running inside a backgroundworker thread now is some code that looks like: SqlConnection conn = new SqlConnection(connstring); SqlCommand cmd = new SqlCommand(query, conn); conn.Open(); SqlDataAdapter sda = new SqlDataAdapter(cmd); sda.Fill(Results); conn.Close(); sda.Dispose(); Where query is a string representing a large, time consuming query, and conn is the connection object. My problem now is I need a stop button. I've come to realize killing the backgroundworker would be worthless because I still want to keep what results are left over after the query is canceled. Plus it wouldn't be able to check the canceled state until after the query. What I've come up with so far: I've been trying to conceptualize how to handle this efficiently without taking too big of a performance hit. My idea was to use a SqlDataReader to read the data from the query piece at a time so that I had a "loop" to check a flag I could set from the GUI via a button. The problem is as far as I know I can't use the Load() method of a datatable and still be able to cancel the sqlcommand. If I'm wrong please let me know because that would make cancelling slightly easier. In light of what I discovered I came to the realization I may only be able to cancel the sqlcommand mid-query if I did something like the below (pseudo-code): while(reader.Read()) { //check flag status //if it is set to 'kill' fire off the kill thread //otherwise populate the datatable with what was read } However, it would seem to me this would be highly ineffective and possibly costly. Is this the only way to kill a sqlcommand in progress that absolutely needs to be in a datatable? Any help would be appreciated!

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