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  • Optimising a query for Top 5% of users

    - by Nai
    On my website, there exists a group of 'power users' who are fantastic and adding lots of content on to my site. However, their prolific activities has led to their profile pages slowing down a lot. For 95% of the other users, the SPROC that is returning the data is very quick. It's only for these group of power users, the very same SPROC is slow. How does one go about optimising the query for this group of users? You can assume that the right indexes have already been constructed. EDIT: Ok, I think I have been a bit too vague. To rephrase the question, how can I optimise my site to enhance the performance for these 5% of users. Given that this SPROC is the same one that is in use for every user and that it is already well optimised, I am guessing the next steps are to explore caching possibilities on the data and application layers?

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  • SQL University: Database testing and refactoring tools and examples

    - by Mladen Prajdic
    This is a post for a great idea called SQL University started by Jorge Segarra also famously known as SqlChicken on Twitter. It’s a collection of blog posts on different database related topics contributed by several smart people all over the world. So this week is mine and we’ll be talking about database testing and refactoring. In 3 posts we’ll cover: SQLU part 1 - What and why of database testing SQLU part 2 - What and why of database refactoring SQLU part 3 - Database testing and refactoring tools and examples This is the third and last part of the series and in it we’ll take a look at tools we can test and refactor with plus some an example of the both. Tools of the trade First a few thoughts about how to go about testing a database. I'm firmily against any testing tools that go into the database itself or need an extra database. Unit tests for the database and applications using the database should all be in one place using the same technology. By using database specific frameworks we fragment our tests into many places and increase test system complexity. Let’s take a look at some testing tools. 1. NUnit, xUnit, MbUnit All three are .Net testing frameworks meant to unit test .Net application. But we can test databases with them just fine. I use NUnit because I’ve always used it for work and personal projects. One day this might change. So the thing to remember is to be flexible if something better comes along. All three are quite similar and you should be able to switch between them without much problem. 2. TSQLUnit As much as this framework is helpful for the non-C# savvy folks I don’t like it for the reason I stated above. It lives in the database and thus fragments the testing infrastructure. Also it appears that it’s not being actively developed anymore. 3. DbFit I haven’t had the pleasure of trying this tool just yet but it’s on my to-do list. From what I’ve read and heard Gojko Adzic (@gojkoadzic on Twitter) has done a remarkable job with it. 4. Redgate SQL Refactor and Apex SQL Refactor Neither of these refactoring tools are free, however if you have hardcore refactoring planned they are worth while looking into. I’ve only used the Red Gate’s Refactor and was quite impressed with it. 5. Reverting the database state I’ve talked before about ways to revert a database to pre-test state after unit testing. This still holds and I haven’t changed my mind. Also make sure to read the comments as they are quite informative. I especially like the idea of setting up and tearing down the schema for each test group with NHibernate. Testing and refactoring example We’ll take a look at the simple schema and data test for a view and refactoring the SELECT * in that view. We’ll use a single table PhoneNumbers with ID and Phone columns. Then we’ll refactor the Phone column into 3 columns Prefix, Number and Suffix. Lastly we’ll remove the original Phone column. Then we’ll check how the view behaves with tests in NUnit. The comments in code explain the problem so be sure to read them. I’m assuming you know NUnit and C#. T-SQL Code C# test code USE tempdbGOCREATE TABLE PhoneNumbers( ID INT IDENTITY(1,1), Phone VARCHAR(20))GOINSERT INTO PhoneNumbers(Phone)SELECT '111 222333 444' UNION ALLSELECT '555 666777 888'GO-- notice we don't have WITH SCHEMABINDINGCREATE VIEW vPhoneNumbersAS SELECT * FROM PhoneNumbersGO-- Let's take a look at what the view returns -- If we add a new columns and rows both tests will failSELECT *FROM vPhoneNumbers GO -- DoesViewReturnCorrectColumns test will SUCCEED -- DoesViewReturnCorrectData test will SUCCEED -- refactor to split Phone column into 3 partsALTER TABLE PhoneNumbers ADD Prefix VARCHAR(3)ALTER TABLE PhoneNumbers ADD Number VARCHAR(6)ALTER TABLE PhoneNumbers ADD Suffix VARCHAR(3)GO-- update the new columnsUPDATE PhoneNumbers SET Prefix = LEFT(Phone, 3), Number = SUBSTRING(Phone, 5, 6), Suffix = RIGHT(Phone, 3)GO-- remove the old columnALTER TABLE PhoneNumbers DROP COLUMN PhoneGO-- This returns unexpected results!-- it returns 2 columns ID and Phone even though -- we don't have a Phone column anymore.-- Notice that the data is from the Prefix column-- This is a danger of SELECT *SELECT *FROM vPhoneNumbers -- DoesViewReturnCorrectColumns test will SUCCEED -- DoesViewReturnCorrectData test will FAIL -- for a fix we have to call sp_refreshview -- to refresh the view definitionEXEC sp_refreshview 'vPhoneNumbers'-- after the refresh the view returns 4 columns-- this breaks the input/output behavior of the database-- which refactoring MUST NOT doSELECT *FROM vPhoneNumbers -- DoesViewReturnCorrectColumns test will FAIL -- DoesViewReturnCorrectData test will FAIL -- to fix the input/output behavior change problem -- we have to concat the 3 columns into one named PhoneALTER VIEW vPhoneNumbersASSELECT ID, Prefix + ' ' + Number + ' ' + Suffix AS PhoneFROM PhoneNumbersGO-- now it works as expectedSELECT *FROM vPhoneNumbers -- DoesViewReturnCorrectColumns test will SUCCEED -- DoesViewReturnCorrectData test will SUCCEED -- clean upDROP VIEW vPhoneNumbersDROP TABLE PhoneNumbers [Test]public void DoesViewReturnCoorectColumns(){ // conn is a valid SqlConnection to the server's tempdb // note the SET FMTONLY ON with which we return only schema and no data using (SqlCommand cmd = new SqlCommand("SET FMTONLY ON; SELECT * FROM vPhoneNumbers", conn)) { DataTable dt = new DataTable(); dt.Load(cmd.ExecuteReader(CommandBehavior.CloseConnection)); // test returned schema: number of columns, column names and data types Assert.AreEqual(dt.Columns.Count, 2); Assert.AreEqual(dt.Columns[0].Caption, "ID"); Assert.AreEqual(dt.Columns[0].DataType, typeof(int)); Assert.AreEqual(dt.Columns[1].Caption, "Phone"); Assert.AreEqual(dt.Columns[1].DataType, typeof(string)); }} [Test]public void DoesViewReturnCorrectData(){ // conn is a valid SqlConnection to the server's tempdb using (SqlCommand cmd = new SqlCommand("SELECT * FROM vPhoneNumbers", conn)) { DataTable dt = new DataTable(); dt.Load(cmd.ExecuteReader(CommandBehavior.CloseConnection)); // test returned data: number of rows and their values Assert.AreEqual(dt.Rows.Count, 2); Assert.AreEqual(dt.Rows[0]["ID"], 1); Assert.AreEqual(dt.Rows[0]["Phone"], "111 222333 444"); Assert.AreEqual(dt.Rows[1]["ID"], 2); Assert.AreEqual(dt.Rows[1]["Phone"], "555 666777 888"); }}   With this simple example we’ve seen how a very simple schema can cause a lot of problems in the whole application/database system if it doesn’t have tests. Imagine what would happen if some outside process would depend on that view. It would get wrong data and propagate it silently throughout the system. And that is not good. So have tests at least for the crucial parts of your systems. And with that we conclude the Database Testing and Refactoring week at SQL University. Hope you learned something new and enjoy the learning weeks to come. Have fun!

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  • How atomic is a SELECT INTO?

    - by leo.pasta
    Last week I got an interesting situation that prompted me to challenge a long standing assumption. I always thought that a SELECT INTO was an atomic statement, i.e. it would either complete successfully or the table would not be created. So I got very surprised when, after a “select into” query was chosen as a deadlock victim, the next execution (as the app would handle the deadlock and retry) would fail with: Msg 2714, Level 16, State 6, Line 1 There is already an object named '#test' in the database. The only hypothesis we could come up was that the “create table” part of the statement was committed independently from the actual “insert”. We can confirm that by capturing the “Transaction Log” event on Profiler (filtering by SPID0). The result is that when we run: SELECT * INTO #results FROM master.sys.objects we get the following output on Profiler: It is easy to see the two independent transactions. Although this behaviour was a surprise to me, it is very easy to workaround it if you feel the need (as we did in this case). You can either change it into independent “CREATE TABLE / INSERT SELECT” or you can enclose the SELECT INTO in an explicit transaction: SET XACT_ABORT ON BEGIN TRANSACTION SELECT * INTO #results FROM master.sys.objects COMMIT

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  • HSSFS Part 3: SQL Saturday is Awesome! And DEFAULT_DOMAIN(), and how I found it

    - by Most Valuable Yak (Rob Volk)
    Just a quick post I should've done yesterday but I was recovering from SQL Saturday #48 in Columbia, SC, where I went to some really excellent sessions by some very smart experts.  If you have not yet attended a SQL Saturday, or its been more than 1 month since you last did, SIGN UP NOW! While searching the OBJECT_DEFINITION() of SQL Server system procedures I stumbled across the DEFAULT_DOMAIN() function in xp_grantlogin and xp_revokelogin.  I couldn't find any information on it in Books Online, and it's a very simple, self-explanatory function, but it could be useful if you work in a multi-domain environment.  It's also the kind of neat thing you can find by using this query: SELECT OBJECT_SCHEMA_NAME([object_id]) object_schema, name FROM sys.all_objects WHERE OBJECT_DEFINITION([object_id]) LIKE '%()%'  ORDER BY 1,2 I'll post some elaborations and enhancements to this query in a later post, but it will get you started exploring the functional SQL Server sea. UPDATE: I goofed earlier and said SQL Saturday #46 was in Columbia. It's actually SQL Saturday #48, and SQL Saturday #46 was in Raleigh, NC.

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  • T-SQL Tuesday #34: Help! I Need Somebody!

    - by Most Valuable Yak (Rob Volk)
    Welcome everyone to T-SQL Tuesday Episode 34!  When last we tuned in, Mike Fal (b|t) hosted Trick Shots.  These highlighted techniques or tricks that you figured out on your own which helped you understand SQL Server better. This month, I'm asking you to look back this past week, year, century, or hour...to a time when you COULDN'T figure it out.  When you were stuck on a SQL Server problem and you had to seek help. In the beginning... SQL Server has changed a lot since I started with it.  <Cranky Old Guy> Back in my day, Books Online was neither.  There were no blogs. Google was the third-place search site. There were perhaps two or three community forums where you could ask questions.  (Besides the Microsoft newsgroups...which you had to access with Usenet.  And endure the wrath of...Celko.)  Your "training" was reading a book, made from real dead trees, that you bought from your choice of brick-and-mortar bookstore. And except for your local user groups, there were no conferences, seminars, SQL Saturdays, or any online video hookups where you could interact with a person. You'd have to call Microsoft Support...on the phone...a LANDLINE phone.  And none of this "SQL Family" business!</Cranky Old Guy> Even now, with all these excellent resources available, it's still daunting for a beginner to seek help for SQL Server.  The product is roughly 1247.4523 times larger than it was 15 years ago, and it's simply impossible to know everything about it.*  So whether you are a beginner, or a seasoned pro of over a decade's experience, what do you do when you need help on SQL Server? That's so meta... In the spirit of offering help, here are some suggestions for your topic: Tell us about a person or SQL Server community who have been helpful to you.  It can be about a technical problem, or not, e.g. someone who volunteered for your local SQL Saturday.  Sing their praises!  Let the world know who they are! Do you have any tricks for using Books Online?  Do you use the locally installed product, or are you completely online with BOL/MSDN/Technet, and why? If you've been using SQL Server for over 10 years, how has your help-seeking changed? Are you using Twitter, StackOverflow, MSDN Forums, or another resource that didn't exist when you started? What made you switch? Do you spend more time helping others than seeking help? What motivates you to help, and how do you contribute? Structure your post along the lyrics to The Beatles song Help! Audio or video renditions are particularly welcome! Lyrics must include reference to SQL Server terminology or community, and performances must be in your voice or include you playing an instrument. These are just suggestions, you are free to write whatever you like.  Bonus points if you can incorporate ALL of these into a single post.  (Or you can do multiple posts, we're flexible like that.)  Help us help others by showing how others helped you! Legalese, Your Rights, Yada yada... If you would like to participate in T-SQL Tuesday please be sure to follow the rules below: Your blog post must be published between Tuesday, September 11, 2012 00:00:00 GMT and Wednesday, September 12, 2012 00:00:00 GMT. Include the T-SQL Tuesday logo (above) and hyperlink it back to this post. If you don’t see your post in trackbacks, add the link to the comments below. If you are on Twitter please tweet your blog using the #TSQL2sDay hashtag.  I can be contacted there as @sql_r, in case you have questions or problems with comments/trackback.  I'll have a follow-up post listing all the contributions as soon as I can. Thank you all for participating, and special thanks to Adam Machanic (b|t) for all his help and for continuing this series!

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  • C# 4.0 'dynamic' and foreach statement

    - by ControlFlow
    Not long time before I've discovered, that new dynamic keyword doesn't work well with the C#'s foreach statement: using System; sealed class Foo { public struct FooEnumerator { int value; public bool MoveNext() { return true; } public int Current { get { return value++; } } } public FooEnumerator GetEnumerator() { return new FooEnumerator(); } static void Main() { foreach (int x in new Foo()) { Console.WriteLine(x); if (x >= 100) break; } foreach (int x in (dynamic)new Foo()) { // :) Console.WriteLine(x); if (x >= 100) break; } } } I've expected that iterating over the dynamic variable should work completely as if the type of collection variable is known at compile time. I've discovered that the second loop actually is looked like this when is compiled: foreach (object x in (IEnumerable) /* dynamic cast */ (object) new Foo()) { ... } and every access to the x variable results with the dynamic lookup/cast so C# ignores that I've specify the correct x's type in the foreach statement - that was a bit surprising for me... And also, C# compiler completely ignores that collection from dynamically typed variable may implements IEnumerable<T> interface! The full foreach statement behavior is described in the C# 4.0 specification 8.8.4 The foreach statement article. But... It's perfectly possible to implement the same behavior at runtime! It's possible to add an extra CSharpBinderFlags.ForEachCast flag, correct the emmited code to looks like: foreach (int x in (IEnumerable<int>) /* dynamic cast with the CSharpBinderFlags.ForEachCast flag */ (object) new Foo()) { ... } And add some extra logic to CSharpConvertBinder: Wrap IEnumerable collections and IEnumerator's to IEnumerable<T>/IEnumerator<T>. Wrap collections doesn't implementing Ienumerable<T>/IEnumerator<T> to implement this interfaces. So today foreach statement iterates over dynamic completely different from iterating over statically known collection variable and completely ignores the type information, specified by user. All that results with the different iteration behavior (IEnumarble<T>-implementing collections is being iterated as only IEnumerable-implementing) and more than 150x slowdown when iterating over dynamic. Simple fix will results a much better performance: foreach (int x in (IEnumerable<int>) dynamicVariable) { But why I should write code like this? It's very nicely to see that sometimes C# 4.0 dynamic works completely the same if the type will be known at compile-time, but it's very sadly to see that dynamic works completely different where IT CAN works the same as statically typed code. So my question is: why foreach over dynamic works different from foreach over anything else?

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  • LINQ to SQL Could not find key member. Only fails on server.

    - by Adam Carr
    I have a scenario where I am inheriting from an abstract class in my partial linq to sql auto generated class implementation. My base abstract class has an abstract property called ID which I have flagged inside my LINQ to SQL model with the instance modifier override. This works fine locally without any issues. I have also done some development on another machine and it works fine there too (both in VS2008 and using Subversion). I am running CI with TeamCity and the build succeeds and deploys as desired. The problem is when the server tries to hit the database for the first time via the LINQ to SQL data context, it generates the following error. "Could not find key member 'Id' of key 'Id' on type 'CustomType'. The key may be wrong or the field or property on 'CustomType' has changed names." I have tried changing my configuration by not implementing the Id field in my base class but this still fails. Why does it work on both of my DEV machines but not on the server? I am using LINQ to SQL in another project that runs on this server just fine. FYI: LINQ to SQL, SQL 2008, .NET 3.5, SERVER 2008, IIS 7.0 UPDATE I have gone back and added the same table a second time in the same data model but without a base class and have then displayed the results from that table and got no errors. This tells me it has something to do with my base abstract class and the need to flag a property on one of my linq to sql model classes (that belongs to a key relationship) with the instance modifier of override. No answer to this yet but am getting closer. UPDATE I have fixed my issue by simply changing my approach to my problem but I am still interested in why this doesn't work. I created a new WinSrv2008 VPC and patched it, deployed a pre-built version of my site to it and still got the same error. I now assume the issue is like what the person said here, a dependency issue with VS2008. My question is what or what? Will install VS2008 on the VPC to see if it works after that.

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  • Grant Showplan : MS SQL Server 2005

    SQL version applied to: 2005 Grant Showplan The SHOWPLAN permission only governs who can run the various SET SHOWPLAN statements. There is no impact on performance of this. And with some of the SHOWPLAN statement in effect, the statement(s) is not executed and goes through compilation phase only.  read moreBy Sachin DiwakerDid you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • sql statement supposed to have 2 distinct rows, but only 1 is returned. for C# windows

    - by jello
    yeah so I have an sql statement that is supposed to return 2 rows. the first with psychological_id = 1, and the second, psychological_id = 2. here is the sql statement select * from psychological where patient_id = 12 and symptom = 'delire'; But with this code, with which I populate an array list with what is supposed to be 2 different rows, two rows exist, but with the same values: the second row. OneSymptomClass oneSymp = new OneSymptomClass(); ArrayList oneSympAll = new ArrayList(); string connStrArrayList = "Data Source=.\\SQLEXPRESS;AttachDbFilename=|DataDirectory|\\PatientMonitoringDatabase.mdf; " + "Initial Catalog=PatientMonitoringDatabase; " + "Integrated Security=True"; string queryStrArrayList = "select * from psychological where patient_id = " + patientID.patient_id + " and symptom = '" + SymptomComboBoxes[tag].SelectedItem + "';"; using (var conn = new SqlConnection(connStrArrayList)) using (var cmd = new SqlCommand(queryStrArrayList, conn)) { conn.Open(); using (SqlDataReader rdr = cmd.ExecuteReader()) { while (rdr.Read()) { oneSymp.psychological_id = Convert.ToInt32(rdr["psychological_id"]); oneSymp.patient_history_date_psy = (DateTime)rdr["patient_history_date_psy"]; oneSymp.strength = Convert.ToInt32(rdr["strength"]); oneSymp.psy_start_date = (DateTime)rdr["psy_start_date"]; oneSymp.psy_end_date = (DateTime)rdr["psy_end_date"]; oneSympAll.Add(oneSymp); } } conn.Close(); } OneSymptomClass testSymp = oneSympAll[0] as OneSymptomClass; MessageBox.Show(testSymp.psychological_id.ToString()); the message box outputs "2", while it's supposed to output "1". anyone got an idea what's going on?

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  • i got sql syntax error when i debug my application..

    - by newBie
    hi..i want to update my database using formatsqlparam..but when i debug it, it has error saying "Incorrect syntax near ','." this is my code: Dim sql2 As String = "update infoHotel set nameHotel = N" & FormatSqlParam(hotel) & _ ", knownAs1 = N" & FormatSqlParam(KnownAs(0)) & _ ", knownAs2 = N" & FormatSqlParam(KnownAs(1)) & _ ", knownAs3 = N" & FormatSqlParam(KnownAs(2)) & _ ", knownAs4 = N" & FormatSqlParam(KnownAs(3)) & _ ", streetAddress = N" & FormatSqlParam(StreetAddress) & _ ", locality = N" & FormatSqlParam(Locality) & _ ", postalCode = N" & FormatSqlParam(PostalCode) & _ ", country = N" & FormatSqlParam(Country) & _ ", addressFull = N" & FormatSqlParam(address) & _ ", tel = N" & FormatSqlParam(contact) & "," Dim objCommand3 As New SqlCommand(sql2, conn) objCommand3.ExecuteNonQuery() maybe i missing some syntax..but couldnt find where it is..hope somebody can help..thnks in advance..im using vb.net and sql

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  • Problem inserting in two different tables [closed]

    - by imvarunkmr
    I have written an insert statement which inserts a record into Table1. Table1 has a column "ID" which is an auto_increment(Identity) primary key. How can I fetch the newly generated "ID" and as I need to Insert this value as foreign key in Table2? Note : I have written INSERT statement in a stored procedure and I am calling this procedure using C# Alternative suggestions to link both tables are also welcomed :)

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  • sqlcmd won't execute - Claims Native Client not installed properly

    - by nuit9
    I'm trying to use sqlcmd to execute some SQL scripts. Using a test command with a simple query like: sqlcmd -S HOSTNAME -d MYDATABASE -Q 'SELECT Names FROM Customers' sqlcmd does not appear to make any attempt to connect to the server as it displays this message: Sqlcmd: Error: Connection failure. SQL Native Client is not installed correctly. To correct this, run SQL Server Setup. The native client was presumably installed as part of the SQL Server setup and likely correctly. I actually get this message on any machine with SQL server installed trying to use sqlcmd so it's not a matter of the installation being corrupt. Unfortunately the message really tells me nothing about the problem so I don't know what the real issue is. I know the SQL Native client is working properly since a vbscript was able to execute SQL queries against the database. Is there some additional configuration needed to use sqlcmd?

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  • Running SQL*Plus with bash causes wrong encoding

    - by Petr Mensik
    I have a problem with running SQL*Plus in the bash. Here is my code #!/bin/bash #curl http://192.168.168.165:8080/api_test/xsql/f_exp_order_1016.xsql > script.sql wget -O script.sql 192.168.168.165:8080/api_test/xsql/f_exp_order_1016.xsql set NLS_LANG=_.UTF8 sqlplus /nolog << ENDL connect login/password set sqlblanklines on start script.sql exit <<endl I download the insert statements from our intranet, put it into sql file and run it through SQL*Plus. This is working fine. My problem is that when I save the file script.sql my encoding goes wrong. All special characters(like íášc) are broken and that's causing inserting wrong characters into my DB. Encoding of that file is UTF-8, also UTF-8 is set on the XSQL page on our intranet. So I really don't know where could be a problem. And also any advices regarding to my script are welcomed, I am total newbie in Linux scripting:-)

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  • SQLIO help decipher output

    - by SQL Learner
    When load testing on a SQL Server Box, using following (testfile is 25 GB) sqlio -kW -t8 -s360 -o8 -frandom -b8 -BH -LS g:\testfile.dat > result.txt sqlio -kW -t8 -s360 -o8 -frandom -b64 -BH -LS g:\testfile.dat >> result.txt sqlio -kW -t8 -s360 -o8 -frandom -b128 -BH -LS g:\testfile.dat >> result.txt sqlio -kW -t8 -s360 -o8 -frandom -b256 -BH -LS g:\testfile.dat >> result.txt Can anyone help me decipher output.. I do not understand latency min and average....? What does this number means IOs/sec: 10968.80 MBs/sec: 685.55 latency metrics: Min_Latency(ms): 1 Avg_Latency(ms): 5 Max_Latency(ms): 21

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  • SQL Server 2005: Improving performance for thousands or Insert requests. logout-login time= 120ms.

    - by Rad
    Can somebody shed some lights on how SQL Server 2005 deals with may request issued by a client using ADO.NET 2.0. Below is the shortend output of SQL Trace. I can see that connection pooling is working (I believe there is only one connection being pooled). What is not clear to me is why we have so many sp_reset_connection calls i.e a series of: Audit Login, SQL:BatchStarting, RPC:Starting and Audit Logout for each loop in for loop below. I can see that there is constant switching between tempdb and master database which leads me to conclude that we lost the context when next connection is created by fetching it from the pool based on ConectionString argument. I can see that every 15ms I can get 100-200 login/logout per second (reported at the same time by Profiler). The after 15ms I have again a series fo 100-200 login/logout per second. I need clarification on how this might affect much complex insert queries in production environment. I use Enterprise Library 2006, the code is compiled with VS 2005 and it is a console application that parses a flat file with 10 of thousand of rows grouping parent-child rows, runs on an application server and runs 2 stored procedure on a remote SQL Server 2005 inserting a parent record, retrieves Identity value and using it calls the second stored procedure 1, 2 or multiple times (sometimes several thousands) inserting child records. The child table has close to 10 million records with 5-10 indexes some of them being covering non-clustered. There is a pretty complex Insert trigger that copies inserted detail record to an archive table. All in all I only have 7 inserts per second which means it can take 2-4 hours for 50 thousand records. When I run Profiler on the test server (that is almost equivalent with production server) I can see that there is about 120ms between Audit Logout and Audit Login trace entries which almost give me chance to insert about 8 records. So my question is if there is some way to improve inserting of records since the company loads 100 thousands of records and does daily planning and has SLA to fulfill client request coming as flat file orders and some big files 10 thousands have to be processed(imported quickly). 4 hours to import 60 thousands should be reduced to 30 minutes. I was thinking to use BatchSize of DataAdapter to send multiple stored procedure calls, SQL Bulk inserts to batch multiple inserts from DataReader or DataTable, SSIS fast load. But I don't know how to properly analyze re-indexing and stats population and maybe this has to take some time to finish. What is worse is that the company uses the biggest table for reporting and other online processing and indexes cannot be dropped. I manage transaction manually by setting a field to a value and do an transactional update changing that value to a new value that other applications are using to get committed rows. Please advise how to approach this problem. For now I am trying to have a staging tables with minimal logging in a separate database and no indexes and I will try to do batched (massive) parent child inserts. I believe Production DB has simple recovery model, but it could be full recovery. If DB user that is being used by my .NET console application has bulkadmin role does it mean its bulk inserts are minimally logged. I understand that when a table has clustered and many non-clustered indexes that inserts are still logged for each row. Connection pooling is working, but with many login/logouts. Why? for (int i = 1; i <= 10000; i++){ using (SqlConnection conn = new SqlConnection("server=(local);database=master;integrated security=sspi;")) {conn.Open(); using (SqlCommand cmd = conn.CreateCommand()){ cmd.CommandText = "use tempdb"; cmd.ExecuteNonQuery();}}} SQL Server Profiler trace: Audit Login master 2010-01-13 23:18:45.337 1 - Nonpooled SQL:BatchStarting use tempdb master 2010-01-13 23:18:45.337 RPC:Starting exec sp_reset_conn tempdb 2010-01-13 23:18:45.337 Audit Logout tempdb 2010-01-13 23:18:45.337 2 - Pooled Audit Login -- network protocol master 2010-01-13 23:18:45.383 2 - Pooled SQL:BatchStarting use tempdb master 2010-01-13 23:18:45.383 RPC:Starting exec sp_reset_conn tempdb 2010-01-13 23:18:45.383 Audit Logout tempdb 2010-01-13 23:18:45.383 2 - Pooled Audit Login -- network protocol master 2010-01-13 23:18:45.383 2 - Pooled SQL:BatchStarting use tempdb master 2010-01-13 23:18:45.383 RPC:Starting exec sp_reset_conn tempdb 2010-01-13 23:18:45.383 Audit Logout tempdb 2010-01-13 23:18:45.383 2 - Pooled

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  • Understanding and Controlling Parallel Query Processing in SQL Server

    Data warehousing and general reporting applications tend to be CPU intensive because they need to read and process a large number of rows. To facilitate quick data processing for queries that touch a large amount of data, Microsoft SQL Server exploits the power of multiple logical processors to provide parallel query processing operations such as parallel scans. Through extensive testing, we have learned that, for most large queries that are executed in a parallel fashion, SQL Server can deliver linear or nearly linear response time speedup as the number of logical processors increases. However, some queries in high parallelism scenarios perform suboptimally. There are also some parallelism issues that can occur in a multi-user parallel query workload. This white paper describes parallel performance problems you might encounter when you run such queries and workloads, and it explains why these issues occur. In addition, it presents how data warehouse developers can detect these issues, and how they can work around them or mitigate them.

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  • SQL Pre-Con…at the Beach

    - by Argenis
      Building upon the success of SQL Rally 2012 (where we packed a room full of DBAs), my friend Robert Davis [Twitter|Blog] and yours truly will be again delivering our day-long Pre-Conference “Demystifying Database Administration Best Practices” this Friday (6/8/2012) – right before SQLSaturday #132 in Pensacola, FL. If you are in the vicinity of Pensacola, come join us! We had tons of fun at Rally. Robert and I love sharing tips and stories that will help you on your day to day duties as a DBA. Some of the topics that we’ll touch on (this is by no means a comprehensive list) Active Directory configuration for SQL Server Deployments Windows Server Deployments Storage and I/O High Availability / Disaster Recovery / Business Continuity Replication Day-To-Day Operations Maintenance TempDB Code Reviews Other Database and Server Settings   Follow this link to sign up for the Pre-Con at Pensacola: http://demystifyingdba.eventbrite.com/ Here’s a blog post that Robert made on the subject of Best Practices.  Hope to see you there!

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  • SQL Pre-Con…at the Beach

    - by Argenis
      Building upon the success of SQL Rally 2012 (where we packed a room full of DBAs), my friend Robert Davis [Twitter|Blog] and yours truly will be again delivering our day-long Pre-Conference “Demystifying Database Administration Best Practices” this Friday (6/8/2012) – right before SQLSaturday #132 in Pensacola, FL. If you are in the vicinity of Pensacola, come join us! We had tons of fun at Rally. Robert and I love sharing tips and stories that will help you on your day to day duties as a DBA. Some of the topics that we’ll touch on (this is by no means a comprehensive list) Active Directory configuration for SQL Server Deployments Windows Server Deployments Storage and I/O High Availability / Disaster Recovery / Business Continuity Replication Day-To-Day Operations Maintenance TempDB Code Reviews Other Database and Server Settings   Follow this link to sign up for the Pre-Con at Pensacola: http://demystifyingdba.eventbrite.com/ Here’s a blog post that Robert made on the subject of Best Practices.  Hope to see you there!

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  • Windows Azure Use Case: Hybrid Applications

    - by BuckWoody
    This is one in a series of posts on when and where to use a distributed architecture design in your organization's computing needs. You can find the main post here: http://blogs.msdn.com/b/buckwoody/archive/2011/01/18/windows-azure-and-sql-azure-use-cases.aspx  Description: Organizations see the need for computing infrastructures that they can “rent” or pay for only when they need them. They also understand the benefits of distributed computing, but do not want to create this infrastructure themselves. However, they may have considerations that prevent them from moving all of their current IT investment to a distributed environment: Private data (do not want to send or store sensitive data off-site) High dollar investment in current infrastructure Applications currently running well, but may need additional periodic capacity Current applications not designed in a stateless fashion In these situations, a “hybrid” approach works best. In fact, with Windows Azure, a hybrid approach is an optimal way to implement distributed computing even when the stipulations above do not apply. Keeping a majority of the computing function in an organization local while exploring and expanding that footprint into Windows and SQL Azure is a good migration or expansion strategy. A “hybrid” architecture merely means that part of a computing cycle is shared between two architectures. For instance, some level of computing might be done in a Windows Azure web-based application, while the data is stored locally at the organization. Implementation: There are multiple methods for implementing a hybrid architecture, in a spectrum from very little interaction from the local infrastructure to Windows or SQL Azure. The patterns fall into two broad schemas, and even these can be mixed. 1. Client-Centric Hybrid Patterns In this pattern, programs are coded such that the client system sends queries or compute requests to multiple systems. The “client” in this case might be a web-based codeset actually stored on another system (which acts as a client, the user’s device serving as the presentation layer) or a compiled program. In either case, the code on the client requestor carries the burden of defining the layout of the requests. While this pattern is often the easiest to code, it’s the most brittle. Any change in the architecture must be reflected on each client, but this can be mitigated by using a centralized system as the client such as in the web scenario. 2. System-Centric Hybrid Patterns Another approach is to create a distributed architecture by turning on-site systems into “services” that can be called from Windows Azure using the service Bus or the Access Control Services (ACS) capabilities. Code calls from a series of in-process client application. In this pattern you move the “client” interface into the server application logic. If you do not wish to change the application itself, you can “layer” the results of the code return using a product (such as Microsoft BizTalk) that exposes a Web Services Definition Language (WSDL) endpoint to Windows Azure using the Application Fabric. In effect, this is similar to creating a Service Oriented Architecture (SOA) environment, and has the advantage of de-coupling your computing architecture. If each system offers a “service” of the results of some software processing, the operating system or platform becomes immaterial, assuming it adheres to a service contract. There are important considerations when you federate a system, whether to Windows or SQL Azure or any other distributed architecture. While these considerations are consistent with coding any application for distributed computing, they are especially important for a hybrid application. Connection resiliency - Applications on-premise normally have low-latency and good connection properties, something you’re not always guaranteed in a distributed and hybrid application. Whether a centralized client or a distributed one, the code should be able to handle extended retry logic. Authorization and Access - In a single authorization environment like a Active Directory domain, security is handled at a user-password level. In a distributed computing environment, you have more options. You can mitigate this with  using The Windows Azure Application Fabric feature of ACS to make the Azure application aware of the App Fabric as an ADFS provider. However, a claims-based authentication structure is often a superior choice.  Consistency and Concurrency - When you have a Relational Database Management System (RDBMS), Consistency and Concurrency are part of the design. In a Service Architecture, you need to plan for sequential message handling and lifecycle. Resources: How to Build a Hybrid On-Premise/In Cloud Application: http://blogs.msdn.com/b/ignitionshowcase/archive/2010/11/09/how-to-build-a-hybrid-on-premise-in-cloud-application.aspx  General Architecture guidance: http://blogs.msdn.com/b/buckwoody/archive/2010/12/21/windows-azure-learning-plan-architecture.aspx   

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  • T-SQL Tuesday #006: LOB, row-overflow and locking behavior

    - by Michael Zilberstein
    This post is my contribution to T-SQL Tuesday #006 , hosted this time by Michael Coles . Actually this post was born last Thursday when I attended Kalen Delaney's "Deep dive into SQL Server Internals" seminar in Tel-Aviv. I asked question, Kalen didn't have answer at hand, so during a break I created demo in order to check certain behavior. Demo goes later in this post but first small teaser. I have MyTable table with 10 rows. I take 2 rows that reside on different pages. In first session...(read more)

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  • Troubleshooting High-CPU Utilization for SQL Server

    - by Susantha Bathige
    The objective of this FAQ is to outline the basic steps in troubleshooting high CPU utilization on  a server hosting a SQL Server instance. The first and the most common step if you suspect high CPU utilization (or are alerted for it) is to login to the physical server and check the Windows Task Manager. The Performance tab will show the high utilization as shown below: Next, we need to determine which process is responsible for the high CPU consumption. The Processes tab of the Task Manager will show this information: Note that to see all processes you should select Show processes from all user. In this case, SQL Server (sqlserver.exe) is consuming 99% of the CPU (a normal benchmark for max CPU utilization is about 50-60%). Next we examine the scheduler data. Scheduler is a component of SQLOS which evenly distributes load amongst CPUs. The query below returns the important columns for CPU troubleshooting. Note – if your server is under severe stress and you are unable to login to SSMS, you can use another machine’s SSMS to login to the server through DAC – Dedicated Administrator Connection (see http://msdn.microsoft.com/en-us/library/ms189595.aspx for details on using DAC) SELECT scheduler_id ,cpu_id ,status ,runnable_tasks_count ,active_workers_count ,load_factor ,yield_count FROM sys.dm_os_schedulers WHERE scheduler_id See below for the BOL definitions for the above columns. scheduler_id – ID of the scheduler. All schedulers that are used to run regular queries have ID numbers less than 1048576. Those schedulers that have IDs greater than or equal to 1048576 are used internally by SQL Server, such as the dedicated administrator connection scheduler. cpu_id – ID of the CPU with which this scheduler is associated. status – Indicates the status of the scheduler. runnable_tasks_count – Number of workers, with tasks assigned to them that are waiting to be scheduled on the runnable queue. active_workers_count – Number of workers that are active. An active worker is never preemptive, must have an associated task, and is either running, runnable, or suspended. current_tasks_count - Number of current tasks that are associated with this scheduler. load_factor – Internal value that indicates the perceived load on this scheduler. yield_count – Internal value that is used to indicate progress on this scheduler.                                                                 Now to interpret the above data. There are four schedulers and each assigned to a different CPU. All the CPUs are ready to accept user queries as they all are ONLINE. There are 294 active tasks in the output as per the current_tasks_count column. This count indicates how many activities currently associated with the schedulers. When a  task is complete, this number is decremented. The 294 is quite a high figure and indicates all four schedulers are extremely busy. When a task is enqueued, the load_factor  value is incremented. This value is used to determine whether a new task should be put on this scheduler or another scheduler. The new task will be allocated to less loaded scheduler by SQLOS. The very high value of this column indicates all the schedulers have a high load. There are 268 runnable tasks which mean all these tasks are assigned a worker and waiting to be scheduled on the runnable queue.   The next step is  to identify which queries are demanding a lot of CPU time. The below query is useful for this purpose (note, in its current form,  it only shows the top 10 records). SELECT TOP 10 st.text  ,st.dbid  ,st.objectid  ,qs.total_worker_time  ,qs.last_worker_time  ,qp.query_plan FROM sys.dm_exec_query_stats qs CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) st CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle) qp ORDER BY qs.total_worker_time DESC This query as total_worker_time as the measure of CPU load and is in descending order of the  total_worker_time to show the most expensive queries and their plans at the top:      Note the BOL definitions for the important columns: total_worker_time - Total amount of CPU time, in microseconds, that was consumed by executions of this plan since it was compiled. last_worker_time - CPU time, in microseconds, that was consumed the last time the plan was executed.   I re-ran the same query again after few seconds and was returned the below output. After few seconds the SP dbo.TestProc1 is shown in fourth place and once again the last_worker_time is the highest. This means the procedure TestProc1 consumes a CPU time continuously each time it executes.      In this case, the primary cause for high CPU utilization was a stored procedure. You can view the execution plan by clicking on query_plan column to investigate why this is causing a high CPU load. I have used SQL Server 2008 (SP1) to test all the queries used in this article.

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  • SQL Server Scripts I Use

    - by Bill Graziano
    When I get to a new client I usually find myself using the same set of scripts for maintenance and troubleshooting.  These are all drop in solutions for various maintenance issues. Reindexing.  I use Michelle Ufford’s (SQLFool) re-indexing script.  I like that it has a throttle and only re-indexes when needed.  She also has a variety of other interesting scripts on her blog too. Server Activity.  Adam Machanic is up to version 10 of sp_WhoIsActive.  It’s a great replacement for the sp_who* stored procedures and does so much more.  If a server is acting funny this is one of the first tools I use. Backups.  Tara Kizer has a great little T-SQL script for SQL Server backups.  Wait Stats.  Paul Randal has a great script to display wait stats.  The biggest benefit for me is that his script filters out at least three dozen wait stats that I just don’t care about (for example LAZYWRITER_SLEEP). Update Statistics.  I didn’t find anything I liked so I wrote a simple script to update stats myself.  The big need for me was that it had to run inside a time window and update the oldest statistics first.  Is there a better one? Diagnostic Queries.  Glenn Berry has a huge collection of DMV queries available.  He also just highlighted five of them including two I really like dealing with unused indexes and suggested indexes. Single Use Query Plans.  Kim Tripp has a script that counts the number of single-use query plans.  This should guide you in whether to enable the Optimize for Adhoc Workloads option in SQL Server 2008. Granting Permissions to Developers.  This is one of those scripts I didn’t even know I needed until I needed it.  Kendra Little wrote it to grant a login read-only permission to all the databases.  It also grants view server state and a few other handy permissions.   What else do you use?  What should I add to my list?

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