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  • Converting to a column oriented array in Java

    - by halfwarp
    Although I have Java in the title, this could be for any OO language. I'd like to know a few new ideas to improve the performance of something I'm trying to do. I have a method that is constantly receiving an Object[] array. I need to split the Objects in this array through multiple arrays (List or something), so that I have an independent list for each column of all arrays the method receives. Example: List<List<Object>> column-oriented = new ArrayList<ArrayList<Object>>(); public void newObject(Object[] obj) { for(int i = 0; i < obj.length; i++) { column-oriented.get(i).add(obj[i]); } } Note: For simplicity I've omitted the initialization of objects and stuff. The code I've shown above is slow of course. I've already tried a few other things, but would like to hear some new ideas. How would you do this knowing it's very performance sensitive?

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  • Indexing only one MySQL column value

    - by BrainCore
    I have a MySQL InnoDB table with a status column. The status can be 'done' or 'processing'. As the table grows, at most .1% of the status values will be 'processing,' whereas the other 99.9% of the values will be 'done.' This seems like a great candidate for an index due to the high selectivity for 'processing' (though not for 'done'). Is it possible to create an index for the status column that only indexes the value 'processing'? I do not want the index to waste an enormous amount of space indexing 'done.'

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  • Identity column SQL Server 2005 inserting same value twice

    - by DannykPowell
    I have a stored procedure that inserts into a table (where there is an identity column that is not the primary key- the PK is inserted initially using the date/time to generate a unique value). We then use SCOPEIDENTITY() to get the value inserted, then there is some logic to generate the primary key field value based on this value, which is then updated back to the table. In some situations the stored procedure is called simultaneously by more than one process, resulting in "Violation of PRIMARY KEY constraint..." errors. This would seem to indicate that the identity column is allowing the same number to be inserted for more than one record. First question- how is this possible? Second question- how to stop it...there's no error handling currently so I'm going to add some try/ catch logic- but would like to understand the problem fully to deal with properly

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  • Query a column and a calculation of columns at the same time PostgreSQL

    - by pablo
    Hi I have two tables, Products and BundleProducts that have o2o relation with BaseProducts. A BundleProduct is a collection of Products using a m2m realtion to the Products table. Products has a price column and the price of a BundleProduct is calculated as the sum of the prices of its Products. BaseProducts have columns like name and description so I can query it to get both Products and BundleProducts. Is it possible to query and sort by price both for the price column of the Products and calculated price of the BundleProducts? Thanks

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  • Compute column widths in a HTML-like manner (based on cell contents)

    - by cipak
    Hi, I have a grid of data that I want to export to RTF, PDF etc. using various (and not perfect) PHP converters/generators. What I am missing most is the HTML table automatic adjustment of column widths based on the lengths of strings in the cells (strings contain line breaks which complicate things a bit, as they should be preserved). I need an algorithm that, given the contents of the cells (plain text), a total width of the table and an average width of a character, would return a width for each column. I wouldn't want to reinvent the wheel if something is already available. Of course it can't be perfect if the font is variable width, but an approximation would do just fine. Or maybe it could have a configurable table with widths for each character. Any hint would be appreciated. Thank you.

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  • The effects of Agile Programming can alter the five desirable properties of modeling tools and techniques

    The effects of Agile Programming can alter the five desirable properties of modeling tools and techniques as documented by Pfleeger. The agile methodology does promote human understanding and communication through the use of short iterative software development life cycles which forces stakeholders to review the project and adjust the project for any requirement changes.  Due to the consistent evaluations of a project and requirements, process are continually being refined, upgraded, and compared against other alternatives to ensure the best design delivered to the client. Due to the short repetitive development cycles, increased time is devoted to process management due to the fact that requirements and designs could be constantly changing. This requires additional forecasting, monitoring, and planning for each iteration. Because things can change so rapidly, automated guidance in performing process must be updated for each iteration because the environment and the available reusable process could change. In addition, the original guidance and suggestions for the project also need to be updated to account for these changes as well.   In essence the automation of process execution is supported by the agile methodology because during every iteration all processes must be tested, evaluated to ensure process integrity and compliance with the customer’s requirements. I do not think the agile approach diminishes modeling, in fact I think it increases the modeling because before the start of every development cycle, modeling must be checked for accuracy based on the changed requirements. So in essence the reduced time spent initially designing the models is in fact gained as the project completes every iteration of the project.

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  • Automatic multi-page multi-column flowing text with QtWebkit (HTML/CSS/JS -> PDF)

    - by Peter Boughton
    I have some HTML documents that are converted to PDF, using software that renders using QtWebkit (not sure which version). Currently, the documents have specific tags to split into columns and pages - so whenever the wording changes, it is a manual time-consuming process to move these tags so that the columns and pages fit. Can anyone provide a way to have text auto-wrapped into the next column/page (as appropriate) when it reaches the bottom of the current container? Any HTML, CSS or JS supported by QtWebkit is ok (assuming it works in the PDF converter). (I have tested the webkit-column-* in CSS3 and it appears QtWebkit does not support this.) To make things more exciting, it also needs to: - put a header at the top of each page, with page X of Y numbering; - if an odd number of pages, add a blank page at the end (with no header); - have the ability to say "don't break inside this block" or "don't break after this header" I have put some quick example initial markup and target markup to help explain what I'm trying to do. (The actual documents are far more complicated than that, but I need a simple proof-of-concept before I attack the real ones.) Any suggestions? Update: I've got a partially working solution using Aaron's "filling up" suggestion - I'll post more details in a bit.

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  • DataTable identity column not set after DataAdapter.Update/Refresh on table with "instead of"-trigge

    - by Arno
    Within our unit tests we use plain ADO.NET (DataTable, DataAdapter) for preparing the database resp. checking the results, while the tested components themselves run under NHibernate 2.1. .NET version is 3.5, SqlServer version is 2005. The database tables have identity columns as primary keys. Some tables apply instead-of-insert/update triggers (this is due to backward compatibility, nothing I can change). The triggers generally work like this: create trigger dbo.emp_insert on dbo.emp instead of insert as begin set nocount on insert into emp ... select @@identity end The insert statement issued by the ADO.NET DataAdapter (generated on-the-fly by a thin ADO.NET wrapper) tries to retrieve the identity value back into the DataRow: exec sp_executesql N' insert into emp (...) values (...); select id, ... from emp where id = @@identity ' But the DataRow's id-Column is still 0. When I remove the trigger temporarily, it works fine - the id-Column then holds the identity value set by the database. NHibernate on the other hand uses this kind of insert statement: exec sp_executesql N' insert into emp (...) values (...); select scope_identity() ' This works, the NHibernate POCO has its id property correctly set right after flushing. Which seems a little bit counter-intuitive to me, as I expected the trigger to run in a different scope, hence @@identity should be a better fit than scope_identity(). So I thought no problem, I will apply scope_identity() instead of @@identity under ADO.NET as well. But this has no effect, the DataRow value is still not updated accordingly. And now for the best part: When I copy and paste those two statements from SqlServer profiler into a Management Studio query (that is including "exec sp_executesql"), and run them there, the results seem to be inverse! There the ADO.NET version works, and the NHibernate version doesn't (select scope_identity() returns null). I tried several times to verify, but to no avail. Of course this just shows the resultset coming from the database, whatever happens inside NHibernate and ADO.NET is another topic. Also, several session properties defined by T-SQL SET are different in the two scenarios (Management Studio query vs. application at runtime) This is a real puzzle to me. I would be happy about any insights on that. Thank you!

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  • Column-oriented DBMS and JOIN operations

    - by André
    From some of the research I've done on NoSQL, column-oriented databases (like HBase or Cassandra) seem to solve the problem of costly JOIN operations, but I don't get how this approach solves this problem. Can anyone explain it to me and/or link me to interesting documentation regarding this area? Thanks

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  • How to set two column unique in SQL.

    - by sxingfeng
    I am creating a table ,in the table two column is unique, I mean columnA and columnB do not have same value: such as : Table X A B 1 2(RIGHT,unique) 2 2(RIGHT, unique) 1 3(RIGHT, not unique) 2 3(RIGHT, not unique) 1 2 (WRONG, not unique) How to create such a table? many thanks!

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  • Simple 2 column CSS layout with nested divs

    - by Dan
    Hello, I have good familiarity with CSS but for some reason I am unable to achieve the result I want in this case. Here is the link to my test site http://danberinger.com/test.html Keep in mind that I want a 2 column layout and that the background wrapper color (gray) is not showing. Instead the body background color image is being put in place of where the wrapper background should be. Any suggestions would be greatly appreciated.

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  • MySQL ALTER TABLE on very large table - is it safe to run it?

    - by Timothy Mifsud
    I have a MySQL database with one particular MyISAM table of above 4 million rows. I update this table about once a week with about 2000 new rows. After updating, I then perform the following statement: ALTER TABLE x ORDER BY PK DESC i.e. I order the table in question by the primary key field in descending order. This has not given me any problems on my development machine (Windows with 3GB memory), but, even though 3 times I have tried it successfully on the production Linux server (with 512MB RAM - and achieving the resulted sorted table in about 6 minutes each time), the last time I tried it I had to stop the query after about 30 minutes and rebuild the database from a backup. I have started to wonder whether a 512MB server can cope with that statement (on such a large table) as I have read that a temporary table is created to perform the ALTER TABLE command?! And, if it can be safely run, what should be the expected time for the alteration of the table? Thanks in advance, Tim

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  • Modify site column(type text) to allow more than 255 characters

    - by alienavatar
    Hi friends I have created custom site column with type text and I included in one of content types. But it is allowing me for 255 characters only. In which way I can extend it, say 1024 characters. I did this before by mentioning somewhere in web.config file but I forgot how i did. Can anyone please tell me how can I achieve this. Thanks in advance.

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  • C# Find out what column caused the Sql Exception

    - by PaN1C_Showt1Me
    Hi. I'm getting an exception from SQL Data Reader (MS SQL as datastore) and I'd like to know which column name causes this Exception to be thrown. But I cannot find it in the InnerException.. nowhere. ((System.InvalidOperationException)ex.InnerException).StackTrace: System.Data.SqlClient.SqlDataReader.ReadColumnHeader(Int32 i) System.Data.SqlClient.SqlDataReader.IsDBNull(Int32 i) ... Where is it hidden please ?

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  • Why column rename script generated by SSMS uses temporary name?

    - by abatishchev
    When I rename a table column in Designer mode in SQL Server Management Studio 2008 (both R2 and non-R2) and generate a change script it looks like this: EXECUTE sp_rename N'table.column', N'Tmp_columnNew', 'COLUMN' GO EXECUTE sp_rename N'table.Tmp_columnNew', N'columnNew', 'COLUMN' GO What for temporary column name is used? Why don't rename at once?

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  • mysql join with multiple values in one column

    - by CYREX
    I need to make a query that creates 3 columns that come from 2 tables which have the following relations: TABLE 1 has Column ID that relates to TABLE 2 with column ID2 In TABLE 1 there is a column called user In TABLE 2 there is a column called names There can be 1 unique user but there can be many names associated to that user. If i do the following i get all data BUT the user column repeats itself for each name it has associated. What i want is for use to appear unique but the names columns appear with all the names associated to the user column but separated by commas, like the following: select user,names from TABLE1 left join TABLE2 on TABLE1.id = TABLE2.id This will show the users repeated everytime a name appears for that user. what i want is to appear like this: USER - NAMES cyrex - pedrox, rambo, zelda homeboy - carmen, carlos, tom, sandra jerry - seinfeld, christine ninja - soloboy etc....

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  • MySQL Export with Column Heading

    - by st4nt0n
    Hello - I am very, very, new to mySQL. I've got experience in general technical terms, but not with the syntax or concepts of mySQL. I have been tasked with exporting a table from MySQL into a pipe delimited .txt or .xls that I can use to add 7500 more records to manually, then import back into the table. I tried to use INTO OUTFILE, but I don't get column headings, which I need for reference to merge the new records. Is there a good resource that can explain this to a complete novice? I would usually go down to my bookstore and start learning, but I'm on a bit of a time crunch. Thanks all!

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  • Problem with table resizing after automatically removing from jquery one column (this only happens i

    - by user297433
    Hi. I have a table with some columns. Something like this: tr1td1 one remove button tr1td2 one remove button ... The table has the size of the div#outer When I click remove button I remove with jquery the entire column . In Firefox everything's fine the table's columns resize to fill the div but in Internet Explorer the table's columns remain just as they are. It's like the browser doesn't refresh the css style. Because if I refresh the page the table looks just as it shoud be. Any ideas?

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  • Alter table add multiple columns ms sql

    - by phenevo
    Is anyone can tell me where is mistake in this query ALTER TABLE Countries ADD ( HasPhotoInReadyStorage bit, HasPhotoInWorkStorage bit, HasPhotoInMaterialStorage bit, HasText bit); ALTER TABLE Regions ADD ( HasPhotoInReadyStorage bit, HasPhotoInWorkStorage bit, HasPhotoInMaterialStorage bit HasText bit); ALTER TABLE Provinces ADD ( HasPhotoInReadyStorage bit, HasPhotoInWorkStorage bit, HasPhotoInMaterialStorage bit HasText bit); ALTER TABLE Cities ADD ( HasPhotoInReadyStorage bit, HasPhotoInWorkStorage bit, HasPhotoInMaterialStorage bit HasText bit); Alter table Hotels Add { HasPhotoInReadyStorage bit, HasPhotoInWorkStorage bit, HasPhotoInMaterialStorage bit, HasHotelPhotoInReadyStorage bit, HasHotelPhotoInWorkStorage bit, HasHotelPhotoInMaterialStorage bit, HasReporterData bit, HasMovieInReadyStorage bit, HasMovieInWorkStorage bit, HasMovieInMaterialStorage bit }; I get errors: Msg 102, Level 15, State 1, Line 2 Incorrect syntax near '('. Msg 102, Level 15, State 1, Line 9 Incorrect syntax near '('. Msg 102, Level 15, State 1, Line 15 Incorrect syntax near '('. Msg 102, Level 15, State 1, Line 22 Incorrect syntax near '('. Msg 102, Level 15, State 1, Line 29 Incorrect syntax near '{'.

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  • forcing Management Studio to use alter table instead of drop/recreate

    - by marco
    Hi! I'm wondering if is there a way to force MSSQL Management Studio to produce a script like this: ALTER TABLE Mytable ADD MyCol bit NOT NULL CONSTRAINT MyColDefault DEFAULT 0 WITH VALUES ALTER TABLE [dbo].Mytable ALTER COLUMN MyCol2 int NULL GO when I alter a very simple property of a column on a table. If I do this in the designer and ask for the produced script, the script doesn't do such simple tasks, but instead copies all the data in a tmp table, drops the original table, renames the tmp table with the original table name. And, of course, drops and recreates every constraint and relationships. Is there any option I can change to change this behaviour? Or, this may be possible, is there some danger I don't see in using the simple ALTER TABLE above? thanks.

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  • css display:table first column too wide

    - by Mestore
    I have a css table setup like this: <div class='table'> <div> <span>name</span> <span>details</span> </div> </div> The css for the table is: .table{ display:table; width:100%; } .table div{ text-align:right; display:table-row; border-collapse: separate; border-spacing: 0px; } .table div span:first-child { text-align:right; } .table div span { vertical-align:top; text-align:left; display:table-cell; padding:2px 10px; } As it stands the two columns are split evenly between the space occupied by the width of the table. I'm trying to get the first column only to be as wide as is needed by the text occupying it's cells The table is an unknown width, as are the columns/cells.

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  • Investigating on xVelocity (VertiPaq) column size

    - by Marco Russo (SQLBI)
      In January I published an article about how to optimize high cardinality columns in VertiPaq. In the meantime, VertiPaq has been rebranded to xVelocity: the official name is now “xVelocity in-memory analytics engine (VertiPaq)” but using xVelocity and VertiPaq when we talk about Analysis Services has the same meaning. In this post I’ll show how to investigate on columns size of an existing Tabular database so that you can find the most important columns to be optimized. A first approach can be looking in the DataDir of Analysis Services and look for the folder containing the database. Then, look for the biggest files in all subfolders and you will find the name of a file that contains the name of the most expensive column. However, this heuristic process is not very optimized. A better approach is using a DMV that provides the exact information. For example, by using the following query (open SSMS, open an MDX query on the database you are interested to and execute it) you will see all database objects sorted by used size in a descending way. SELECT * FROM $SYSTEM.DISCOVER_STORAGE_TABLE_COLUMN_SEGMENTS ORDER BY used_size DESC You can look at the first rows in order to understand what are the most expensive columns in your tabular model. The interesting data provided are: TABLE_ID: it is the name of the object – it can be also a dictionary or an index COLUMN_ID: it is the column name the object belongs to – you can also see ID_TO_POS and POS_TO_ID in case they refer to internal indexes RECORDS_COUNT: it is the number of rows in the column USED_SIZE: it is the used memory for the object By looking at the ration between USED_SIZE and RECORDS_COUNT you can understand what you can do in order to optimize your tabular model. Your options are: Remove the column. Yes, if it contains data you will never use in a query, simply remove the column from the tabular model Change granularity. If you are tracking time and you included milliseconds but seconds would be enough, round the data source column to the nearest second. If you have a floating point number but two decimals are good enough (i.e. the temperature), round the number to the nearest decimal is relevant to you. Split the column. Create two or more columns that have to be combined together in order to produce the original value. This technique is described in VertiPaq optimization article. Sort the table by that column. When you read the data source, you might consider sorting data by this column, so that the compression will be more efficient. However, this technique works better on columns that don’t have too many distinct values and you will probably move the problem to another column. Sorting data starting from the lower density columns (those with a few number of distinct values) and going to higher density columns (those with high cardinality) is the technique that provides the best compression ratio. After the optimization you should be able to reduce the used size and improve the count/size ration you measured before. If you are interested in a longer discussion about internal storage in VertiPaq and you want understand why this approach can save you space (and time), you can attend my 24 Hours of PASS session “VertiPaq Under the Hood” on March 21 at 08:00 GMT.

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