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  • Iozone: sensible settings for a server with lots of RAM

    - by Frank Brenner
    I have just acquired a server with: 2x quadcore Xeons 48G ECC RAM 5x 160GB SSDs on an LSI 9260-8i Before deploying the target platform, I'd like to collect as much benchmark data as possible, testing I/O with hardware RAID in various configurations, ZFS zRAID, as well as I/O performance on vSphere and with KVM virtualization. In order to see real disk I/O performance without cache effects, I tried running Iozone with a maximum file of more than twice the physical RAM as recommended in the documentation, so: iozone -a -g100G However, as one might expect, this takes far too long to be practicable. (I stopped the run after seven hours..) I'd like to reduce the range of record and file sizes to values that might reflect realistic performance for an application server, hopefully getting the run times to under an hour or so. Any ideas? Thanks.

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  • SQL? "Show me all the Activities that can be performed by User X."

    - by Casey Fulton
    I'm at my wits end. I've searched like crazy, read plenty of database textbooks and God knows how many online guides, blogs and forums. Can someone put me out of my misery? PseudoSchema Diagram (Warning: although pretty, not in a format even remotely approaching ER diagrams! Primary keys are bold, foreign keys are italics.) Given the above set of tables relating Users to Groups to Privileges, and then a set of Activities that can each require a Privilege to perform, how do you find out this: Show me all the Activities that can be performed by User X. That is: User X is a member of groups G and F; groups G and F correlate to privileges P, Q, R and S; show me all the activities that require privileges either P, Q, R or S. How do you do this?

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  • How do I translate a List<string> into a SqlParameter for a Sql In statement?

    - by KallDrexx
    I seem to be confused on how to perform an In statement with a SqlParameter. So far I have the following code: cmd.CommandText = "Select dscr from system_settings where setting in @settings"; cmd.Connection = conn; cmd.Parameters.Add(new SqlParameter("@settings", settingList)); reader = cmd.ExecuteReader(); settingsList is a List<string>. When cmd.ExecuteReader() is called, I get an ArgumentException due to not being able to map a List<string> to "a known provider type". How do I (safely) perform an In query with SqlCommands?

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  • How can I make Excel correlate data from two data sets into a single graph?

    - by Tom Ritter
    I have two datasets, one being sparser than the other. They look like this: Data Set 1: 4 50 5 55 6 60 7 70 8 80 Data Set 2: 4 10 6 20 8 30 I have several hundred points instead of this few. I want them in the same graph, the X axis being 4-8, the y axis being 0-100ish, and two lines, one for each data set. What I get is two lines, not correlated at all along the X axis, and the X axis being labeled from one of the two datasets, with the labels being wrong for the other. The smaller data set is one-point-per-tick on the x axis, when I need it to skip ticks and actually line up with the other data set. Not married to excel, willing to try this in something else if it's free.

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  • How to get user input for 2 digit data

    - by oneMinute
    In a HTML form user is expect to fill / select some data and trigger an action probably a http-post. If your only requested data field is a "2 digit" you can use html text input element get some data. Then you want to make it useful; enable user easily select data from a 'html select' But not all of your data is well-ordered so eye-searching within these data is somehow cumbersome. Because your data is meaningful with its relations. If there is no primary key for foreign key "12" it should not be shown. Vice versa if this foreign key occurs a lot, then it has some weight and could be displayed with more importance. So, what will be your way? a) Use text input to get data and validate it with regex, javascript, ... b) Use some dropdown select. c) Any other way ? Any answer will appreciated :)

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  • In SQL / MySQL, what is the difference between "On" and "Where" in a join statement?

    - by Jian Lin
    The following statements give the same result (one is using "on", and the other using "where"): mysql> select * from gifts INNER JOIN sentGifts on gifts.giftID = sentGifts.giftID; mysql> select * from gifts INNER JOIN sentGifts where gifts.giftID = sentGifts.giftID; I can only see in a case of a Left Outer Join finding the "unmatched" cases: (to find out the gifts that were never sent by anybody) mysql> select name from gifts LEFT OUTER JOIN sentgifts on gifts.giftID = sentgifts.giftID where sentgifts.giftID IS NULL; In this case, it is first using "on", and then "where". Does the "on" first do the matching, and then "where" does the "secondary" filtering? Or is there a more general rule of using "on" versus "where"? Thanks.

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  • Is there a way to give a subquery an alias in Oracle 11g SQL?

    - by Matt Pascoe
    Is there a way to give a subquery in Oracle 11g an alias like: select * from (select client_ref_id, request from some_table where message_type = 1) abc, (select client_ref_id, response from some_table where message_type = 2) defg where abc.client_ref_id = def.client_ref_id; Otherwise is there a way to join the two subqueries based on the client_ref_id. I realize there is a self join, but on the database I am running on a self join can take up to 5 min to complete (there is some extra logic in the actual query I am running but I have determined the self join is what is causing the issue). The individual subqueries only take a few seconds to complete by them selves. The self join query looks something like: select st.request, st1.request from some_table st, some_table st1 where st.client_ref_id = st1.client_ref_id;

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  • Multiple SQL Standard Instances on 4 Processor/32-core Server

    - by Theowood
    We have a large 4 processor/32-core server with 192GB of memory available in the data center and over twenty small SQL Standard databases to consolidate. They are a mix of SQL 2012 and 2008 R2 for 3rd-party apps. Is there any issue with simply installing two instances of SQL Standard on the server - one for 2012 and one for 2008 R2 ? Each instance will use up to 64GB out of the 192GB and 16 cores. If we did this with Enterprise, the licensing would be a fortune and the Enterprise features are not needed.

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  • LINQ Joins - Performance

    - by Meiscooldude
    I am curious on how exactly LINQ (not LINQ to SQL) is performing is joins behind the scenes in relation to how Sql Server performs joins. Sql Server before executing a query, generates an Execution Plan. The Execution Plan is basically an Expression Tree on what it believes is the best way to execute the query. Each node provides information on whether to do a Sort, Scan, Select, Join, ect. On a 'Join' node in our execution plan, we can see three possible algorithms; Hash Join, Merge Join, and Nested Loops Join. Sql Server will choose which algorithm to for each Join operation based on expected number of rows in Inner and Outer tables, what type of join we are doing (some algorithms don't support all types of joins), whether we need data ordered, and probably many other factors. Join Algorithms: Nested Loop Join: Best for small inputs, can be optimized with ordered inner table. Merge Join: Best for medium to large inputs sorted inputs, or an output that needs to be ordered. Hash Join: Best for medium to large inputs, can be parallelized to scale linearly. LINQ Query: DataTable firstTable, secondTable; ... var rows = from firstRow in firstTable.AsEnumerable () join secondRow in secondTable.AsEnumerable () on firstRow.Field<object> (randomObject.Property) equals secondRow.Field<object> (randomObject.Property) select new {firstRow, secondRow}; SQL Query: SELECT * FROM firstTable fT INNER JOIN secondTable sT ON fT.Property = sT.Property Sql Server might use a Nested Loop Join if it knows there are a small number of rows from each table, a merge join if it knows one of the tables has an index, and Hash join if it knows there are a lot of rows on either table and neither has an index. Does Linq choose its algorithm for joins? or does it always use one?

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  • Parse filename, insert to SQL

    - by jakesankey
    Thanks to Code Poet, I am now working off of this code to parse all .txt files in a directory and store them in a database. I need a bit more help though... The file names are R303717COMP_148A2075_20100520.txt (the middle section is unique per file). I would like to add something to code so that it can parse out the R303717COMP and put that in the left column of the database such as: (this is not the only R number we have) R303717COMP data data data R303717COMP data data data R303717COMP data data data etc Lastly, I would like to have it store each full file name into another table that gets checked so that it doesn't get processed twice.. Any Help is appreciated. using System; using System.Data; using System.Data.SQLite; using System.IO; namespace CSVImport { internal class Program { private static void Main(string[] args) { using (SQLiteConnection con = new SQLiteConnection("data source=data.db3")) { if (!File.Exists("data.db3")) { con.Open(); using (SQLiteCommand cmd = con.CreateCommand()) { cmd.CommandText = @" CREATE TABLE [Import] ( [RowId] integer PRIMARY KEY AUTOINCREMENT NOT NULL, [FeatType] varchar, [FeatName] varchar, [Value] varchar, [Actual] decimal, [Nominal] decimal, [Dev] decimal, [TolMin] decimal, [TolPlus] decimal, [OutOfTol] decimal, [Comment] nvarchar);"; cmd.ExecuteNonQuery(); } con.Close(); } con.Open(); using (SQLiteCommand insertCommand = con.CreateCommand()) { insertCommand.CommandText = @" INSERT INTO Import (FeatType, FeatName, Value, Actual, Nominal, Dev, TolMin, TolPlus, OutOfTol, Comment) VALUES (@FeatType, @FeatName, @Value, @Actual, @Nominal, @Dev, @TolMin, @TolPlus, @OutOfTol, @Comment);"; insertCommand.Parameters.Add(new SQLiteParameter("@FeatType", DbType.String)); insertCommand.Parameters.Add(new SQLiteParameter("@FeatName", DbType.String)); insertCommand.Parameters.Add(new SQLiteParameter("@Value", DbType.String)); insertCommand.Parameters.Add(new SQLiteParameter("@Actual", DbType.Decimal)); insertCommand.Parameters.Add(new SQLiteParameter("@Nominal", DbType.Decimal)); insertCommand.Parameters.Add(new SQLiteParameter("@Dev", DbType.Decimal)); insertCommand.Parameters.Add(new SQLiteParameter("@TolMin", DbType.Decimal)); insertCommand.Parameters.Add(new SQLiteParameter("@TolPlus", DbType.Decimal)); insertCommand.Parameters.Add(new SQLiteParameter("@OutOfTol", DbType.Decimal)); insertCommand.Parameters.Add(new SQLiteParameter("@Comment", DbType.String)); string[] files = Directory.GetFiles(Environment.CurrentDirectory, "TextFile*.*"); foreach (string file in files) { string[] lines = File.ReadAllLines(file); bool parse = false; foreach (string tmpLine in lines) { string line = tmpLine.Trim(); if (!parse && line.StartsWith("Feat. Type,")) { parse = true; continue; } if (!parse || string.IsNullOrEmpty(line)) { continue; } foreach (SQLiteParameter parameter in insertCommand.Parameters) { parameter.Value = null; } string[] values = line.Split(new[] {','}); for (int i = 0; i < values.Length - 1; i++) { SQLiteParameter param = insertCommand.Parameters[i]; if (param.DbType == DbType.Decimal) { decimal value; param.Value = decimal.TryParse(values[i], out value) ? value : 0; } else { param.Value = values[i]; } } insertCommand.ExecuteNonQuery(); } } } con.Close(); } } } }

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  • Is there a way to give a subquery an alias in Oracle 10g SQL?

    - by Matt Pascoe
    Is there a way to give a subquery in Oracle 11g an alias like: select * from (select client_ref_id, request from some_table where message_type = 1) abc, (select client_ref_id, response from some_table where message_type = 2) defg where abc.client_ref_id = def.client_ref_id; Otherwise is there a way to join the two subqueries based on the client_ref_id. I realize there is a self join, but on the database I am running on a self join can take up to 5 min to complete (there is some extra logic in the actual query I am running but I have determined the self join is what is causing the issue). The individual subqueries only take a few seconds to complete by them selves. The self join query looks something like: select st.request, st1.request from some_table st, some_table st1 where st.client_ref_id = st1.client_ref_id;

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  • How does DATEDIFF calculate week differences in SQL Server 2005?

    - by eksortso
    I would like to calculate the difference in weeks between two dates, where two dates are considered part of the same week if their preceding Sunday is the same. Ideally, I'd like to do this using DATEDIFF, instead of learning an elaborate idiom to calculate the value. But I can't tell how it works when weeks are involved. The following query returns 1 and 2. This might make sense if your calendar week begins with a Sunday, i.e. if you run SET DATEFIRST 7 beforehand or if @@DATEFIRST is 7 by default. SET DATEFIRST 7; -- SET DATEFIRST 1; DECLARE @d1 DATETIME, @d2a DATETIME, @d2b DATETIME ; SELECT @d1 = '2010-04-05', -- Monday @d2a = '2010-04-16', -- Following Friday @d2b = '2010-04-18' -- the Sunday following ; SELECT DATEDIFF(week, @d1, @d2a) AS weekdiff_a -- returns 1 ,DATEDIFF(week, @d1, @d2b) AS weekdiff_b -- returns 2 ; So I expected different results if SET DATEFIRST 1 is executed instead of SET DATEFIRST 7. But the return values are the same, regardless! What is going on here? What should I do to get the correct week differences?

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  • SQL - How to display the students with the same age?

    - by Cristian
    the code I wrote only tells me how many students have the same age. I want their names too... SELECT YEAR(CURRENT DATE-DATEOFBIRTH) AS AGE, COUNT(*) AS HOWMANY FROM STUDENTS GROUP BY YEAR(CURRENT DATE-DATEOFBIRTH); this returns something like this: AGE HOWMANY --- ------- 21 3 30 5 Thank you. TABLE STUDENTS COLUMNS: StudentID (primary key), Name(varchar), Firstname(varchar), Dateofbirth(varchar) I was thinking of maybe using the code above and somewhere add the function concat that will put the stundents' names on the same row as in

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  • Efficient Array Storage for Binary Tree

    - by Sundararajan S
    We have to write the nodes of a binary tree to a file. What is the most space efficient way of writing a binary tree . We can store it in array format with parent in position 'i' and its childs in 2i,2i+1. But this will waste lot of space in case of sparse binary trees.

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  • client-side data storage and retrieval with html and javascript

    - by pedalpete
    I'm building what I am hoping to be a fairly simple, quick and dirty demo app. So far, I've managed to build a bunch of components using only html and javascript. I know that eventually I'll hook-up a db, but at this point I'm just trying to show off some functionality. In the page, a user can select a bunch of other users (like friends). Then they go to a separate html page and there is some sorting info based on the selected users. So my first attempt was to put the selected users object into a cookie, and retrieve the cookie on the second page. Unfortunately, if the user changed their selection, the cookie wasn't getting updated, and my searches on StackOverflow seemed to say that deleting and updating cookies is unreliable. I tried function updateCookie(updatedUserList){ jQuery.cookie('userList',null); jQuery.cookie('userList',updatedUserList); } but though it set the cookie to null, it wouldn't update it on the second value. So I decided to put the selected users object into a form. Unfortunately, it looks like I can't retrieve the contents from the form on the client-side, only on the server-side. Is there another way to do this? I've worked in PHP and Rails, but I'm trying to do this quickly and simply before building it out into something larger and am trying to avoid any server-side processing for now, which I have managed to do up to this point.

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  • Custom session state provider needed for DB storage?

    - by subt13
    I know this question is related to many others, but please bear with me. I am trying an experiment to store all information in database tables instead of the ASP.NET session. In ASP.NET 4 one can create a custom provider for session. So, again should I implement a Custom Session-State Provider or should I just disable session (in Web.config)? Thanks! From the comments my question can be misunderstood. Hopefully this tidbit will help clarify: I don't want to store the session in the database. I want to store information in the database that you would typically store in the session. One reason why: I don't want to carry around a session on every page, especially if that page doesn't care about 90 percent of the information in the session

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  • How to change a primary key in SQL to auto_increment?

    - by Jian Lin
    I have a table in MySQL that has a primary key: mysql> desc gifts; +---------------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +---------------+-------------+------+-----+---------+-------+ | giftID | int(11) | NO | PRI | NULL | | | name | varchar(80) | YES | | NULL | | | filename | varchar(80) | YES | | NULL | | | effectiveTime | datetime | YES | | NULL | | +---------------+-------------+------+-----+---------+-------+ but I wanted to make it auto_increment. The following statement failed. How can it be modified so that it can work? thanks mysql> alter table gifts modify giftID int primary key auto_increment; ERROR 1068 (42000): Multiple primary key defined

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  • Read and write .NET Objects in SQL Database without serialization.

    - by Mohit
    Hello, I have a small query. I need to create a Caching Service of my own that will write and read .NET Objects to and from the Database. Now, I have achieved that with the help of Binary Serialization. But the Problem is I need to deliberately marked my objects as [Serializable], which makes me think that what if someone will try to add an object which is not marked as [Serializable]. Thus, I need to find a way to read and write Objects to Database without Serialization. I have one thought too.. As we all know Session can store any object in it. Now, we can make sessions to be stored in the DB, outproc. What mechanism it uses to store these objects without serializing or deserializing. Any help will be highly appreciated. Thanks. M.B

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  • nHibernate storage of an object with self referencing many children and many parents

    - by AdamC
    I have an object called MyItem that references children in the same item. How do I set up an nhibernate mapping file to store this item. public class MyItem { public virtual string Id {get;set;} public virtual string Name {get;set;} public virtual string Version {get;set;} public virtual IList<MyItem> Children {get;set;} } So roughly the hbm.xml would be: <class name="MyItem" table="tb_myitem"> <id name="Id" column="id" type="String" length="32"> <generator class="uuid.hex" /> </id> <property name="Name" column="name" /> <property name="Version" column="version" /> <bag name="Children" cascade="all-delete-orphan" lazy="false"> <key column="children_id" /> <one-to-many class="MyItem" not-found="ignore"/> </bag> </class> This wouldn't work I don't think. Perhaps I need to create another class, say MyItemChildren and use that as the Children member and then do the mapping in that class? This would mean having two tables. One table holds the MyItem and the other table holds references from my item. NOTE: A child item could have many parents.

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