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  • mysql update too slow when joining multiple tables

    - by user293487
    Hi, I have two tables. they looks like as follows: Id (int) Tags char(128). the column Tags in table A does not have value. It is empty. The column Tags in table B has value. What I want to copy the Tags in table B to corresponding place of table A. the mapping is based on Id. My sql query is: update A INNER JOIN B set A.Tags = B.Tags where A.Id = B.Id There are about 2,000,000 rows in table A, and 50,000 rows in table B. The update seems very slow.... Could anyone tell me how to make it run faster?

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  • Inserting asyncronously into Oracle, any benefits?

    - by Karl Trumstedt
    I am using ODP.NET for loading data into Oracle. I am bulking inserts into groups of a 1000 rows each call. Is there any performance benefits in calling my load method asynchronously? So say I want to insert 10000 rows, instead of making 10 calls synchronously I make 10 calls asynchronously. My database is using ASSM right now but otherwise plenty of freelists are used of course. The database server has several cores as well. My initial tests seem to point to a performance increase, but maybe there is something I cannot see? Potential deadlock or contention issues? Of course, there is added complexity in handling transactions and such doing my load this way.

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  • jquery: Toggle elements based on result from a function

    - by Svish
    I have a number of table rows that I would like to toggle the visibility of. They should be visible if a data item I have set on them earlier equals a selected value in a form. This is what I have so far: $('#category-selector').change(function(event) { var category_id = $(this).val(); if(!category_id) { $('tr', '#table tbody').show(); } else { $('tr', '#table tbody').toggle(); } }); Of course this just toggles them on and off. Thing is that I thought I was able to give toggle a function that would decide if each row should be on or off, but it turns out I can only give it a boolean condition which would be an all or nothing deal kind of... So, I have this function: function() { return $(this).data('category_id') == category_id; } How can I use that to go through all the rows and toggle them on or off? Or is there a better approach to this? What should I do?

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  • Performing LINQ Self Join

    - by senfo
    I'm not getting the results I want for a query I'm writing in LINQ using the following: var config = (from ic in repository.Fetch() join oc in repository.Fetch() on ic.Slot equals oc.Slot where ic.Description == "Input" && oc.Description == "Output" select new Config { InputOid = ic.Oid, OutputOid = oc.Oid }).Distinct(); The following SQL returns 53 rows (which is correct), but the above LINQ returns 96 rows: SELECT DISTINCT ic.Oid AS InputOid, oc.Oid AS OutputOid FROM dbo.Config AS ic INNER JOIN dbo.Config AS oc ON ic.Slot = oc.Slot WHERE ic.Description = 'Input' AND oc.Description = 'Output' How would I replicate the above SQL in a LINQ query? Update: I don't think it matters, but I'm working with LINQ to Entities 4.0.

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  • How can i use listDictionary?

    - by Phsika
    i can fill my listdictinary but, if running error returns to me in " foreach (string ky in ld.Keys)"(invalid operation Exception was unhandled) Error Detail : After creating a pointer to the list of sample collection has been changed. C# ListDictionary ld = new ListDictionary(); foreach (DataColumn dc in dTable.Columns) { MessageBox.Show(dTable.Rows[0][dc].ToString()); ld.Add(dc.ColumnName, dTable.Rows[0][dc].ToString()); } foreach (string ky in ld.Keys) if (int.TryParse(ld[ky].ToString(), out QuantityInt)) ld[ky] = "integer"; else if(double.TryParse(ld[ky].ToString(), out QuantityDouble)) ld[ky]="double"; else ld[ky]="nvarchar";

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  • Eliminate duplicates in SQL query

    - by ewdef
    i have a table with 6 fields. the columns are ID, new_id price,title,Img,Active. I have datawhich is duplicated for the price column. When I do a select i want to show only distinct rows where new_id is not the same. e.g.- ID New_ID Price Title Img Active 1 1 20.00 PA-1 0X4... 1 2 1 10.00 PA-10 0X4... 1 3 3 20.00 PA-11 0X4... 1 4 4 30.00 PA-5 0X4... 1 5 9 20.00 PA-99A 0X4... 1 6 3 50.00 PA-55 0X4... 1 When the select statement runs, only rows with ID (1,4,9,6) should show. Reason being the new_ID with the higher price should show up. How can i do this?

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  • adding a background color to search term results

    - by turborogue
    I'm trying to add a background color to a user submitted search result when a user enters a search term on a page (which is basically one big table). This is a text based search. I'm using jquery to show/hide the table rows that do not have the search term as text within the TR, but I'd ideally like to take the additional step of taking the search term (the entered value), and matching any of those text terms in the remaining (showing) rows and adding say a yellow background to the word(s). I know my syntax is currently wrong, just not sure what is correct:) Hopefully this is clear...any help is greatly appreciated! html of form: jquery: $("#searchsubmit").click(function () { var searchexp = document.getElementById('searchbox').value; $("table tr").hide(); $("table tr.header").show(); $('tr:contains('+ searchexp +')').show(); $(searchexp).css('background-color','yellow'); });

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  • What is the best way to embed controls in a list/grid

    - by Brad
    I have a table of about 450 rows that I would like to display in a graphical list for users to view or modify the line items. The users would be selection options from comboboxes and selecting check boxes etc. I have found a listview class that extends the basic listview to allow for embeding objects but it seems kind of slugish when I load all the rows into it. I have used a datagridview in the past for comboboxes and checkboxes, but there was a lot of time invested in getting that up and running...not a big fav of mine. I am looking for sugestions how I can do this with minimal overhead. thanks c#, vs2008, .net 2.0, system.windows.forms

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  • how do I do this UPDATE in sqlite?

    - by Jason S
    I have a table assoc containing columns local_id, remote_id, cachedData I can successfully run an SQLITE query that looks like SELECT a1.local_id, a1.remote_id FROM assoc a1 LEFT JOIN .... so that I identify certain rows of the assoc table that meet my criteria. What I would like to do is to set cachedData to null in those rows. How can I do this? Sqlite doesn't support UPDATE with joins; you can issue subqueries but I can't figure out how to get the syntax correct; it seems nonintuitive to me.

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  • Table Adaptor Error when trying update

    - by JasonMc92
    Hi, I have a rather perplexing issue. I am using VB.net and SQL for my project. I have a database, to which the connection works. I also have a data table and data adaptor, both of which I know work. I am trying to update something in the database, yet it isn't working. Assume everything listed is declared correctly. What am I doing wrong? teacher_control_table.Rows(0)("DATA_TeacherLockPasscode") = txtPasscode1.Text table_adaptor2.Update(teacher_control_table) That last line throws the following exception: InvalidOperationException was unhandled. update requires a valid UpdateCommand when passed DataRow collection with modified rows.

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  • The proccesses finished berfore they become completed

    - by Meysam Javadi
    suppose this scenario: i have a XML file that is uploaded, i read it to a DataTable with ReadXml method. now i want to insert this DataTable to database. i create a t-sql command to insert database(with StoredProcedure) for example var command =string.Format("exec SyncToDB '{0}','{1}", odatarow.ItemArray.GetValue(0), odatarow..ItemArray.GetValue(1)); Hitherto everything is ok but when i run this code ,all of rows not affected to DB, i think that a timeout occur the code execution. *note:*the number of rows is numerous.(25000). how to solve this?

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  • Is a full list returned first and then filtered when using linq to sql to filter data from a databas

    - by RJ
    This is probably a very simple question that I am working through in an MVC project. Here's an example of what I am talking about. I have an rdml file linked to a database with a table called Users that has 500,000 rows. But I only want to find the Users who were entered on 5/7/2010. So let's say I do this in my UserRepository: from u in db.GetUsers() where u.CreatedDate = "5/7/2010" select u (doing this from memory so don't kill me if my syntax is a little off, it's the concept I am looking for) Does this statement first return all 500,000 rows and then filter it or does it only bring back the filtered list?

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  • MySQL, delete and index hint

    - by Manuel Darveau
    I have to delete about 10K rows from a table that has more than 100 million rows based on some criteria. When I execute the query, it takes about 5 minutes. I ran an explain plan (the delete query converted to select * since MySQL does not support explain delete) and found that MySQL uses the wrong index. My question is: is there any way to tell MySQL which index to use during delete? If not, what ca I do? Select to temp table then delete from temp table? Thank you!

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  • Help with a query

    - by stackoverflowuser
    Hi Based on the following table ID Effort Name ------------------------- 1 1 A 2 1 A 3 8 A 4 10 B 5 4 B 6 1 B 7 10 C 8 3 C 9 30 C I want to check if the total effort against a name is less than 40 then add a row with effort = 40 - (Total Effort) for the name. The ID of the new row can be anything. If the total effort is greater than 40 then trucate the data for one of the rows to make it 40. So after applying the logic above table will be ID Effort Name ------------------------- 1 1 A 2 1 A 3 8 A 10 30 A 4 10 B 5 4 B 6 1 B 11 25 B 7 10 C 8 3 C 9 27 C I was thinking of opening a cursor, keeping a counter of the total effort, and based on the logic insert existing and new rows in another temporary table. I am not sure if this is an efficient way to deal with this. I would like to learn if there is a better way.

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  • database row/ record pointers

    - by David
    Hi I don't know the correct words for what I'm trying to find out about and as such having a hard time googling. I want to know whether its possible with databases (technology independent but would be interested to hear whether its possible with Oracle, MySQL and Postgres) to point to specific rows instead of executing my query again. So I might initially execute a query find some rows of interest and then wish to avoid searching for them again by having a list of pointers or some other metadata which indicates the location on a database which I can go to straight away the next time I want those results. I realise there is caching on databases, but I want to keep these "pointers" else where and as such caching doesn't ultimately solve this problem. Is this just an index and I store the index and look up by this? most of my current tables don't have indexes and I don't want the speed decrease that sometimes comes with indexes. So whats the magic term I've been trying to put into google? Cheers

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  • Database design advice needed.

    - by user346271
    Hi all, I'm a lone developer for a telecoms company, and am after some database design advice from anyone with a bit of time to answer. I am inserting into one table ~2 million rows each day, these tables then get archived and compressed on a monthly basis. Each monthly table contains ~15,000,000 rows. Although this is increasing month on month. For every insert I do above I am combining the data from rows which belong together and creating another "correlated" table. This table is currently not being archived, as I need to make sure I never miss an update to the correlated table. (Hope that makes sense) Although in general this information should remain fairly static after a couple of days of processing. All of the above is working perfectly. However my company now wishes to perform some stats against this data, and these tables are getting too large to provide the results in what would be deemed a reasonable time. Even with the appropriate indexes set. So I guess after all the above my question is quite simple. Should I write a script which groups the data from my correlated table into smaller tables. Or should I store the queries result sets in something like memcache? I'm already using mysqls cache, but due to having limited control over how long the data is stored for, it's not working ideally. The main advantages I can see of using something like memcache: No blocking on my correlated table after the query has been cashed. Greater flexibility of sharing the collected data between the backend collector and front end processor. (i.e custom reports could be written in the backend and the results of these stored in the cache under a key which then gets shared with anyone who would want to see the data of this report) Redundancy and scalability if we start sharing this data with a large amount of customers. The main disadvantages I can see of using something like memcache: Data is not persistent if machine is rebooted / cache is flushed. The main advantages of using MySql Persistent data. Less code changes (although adding something like memcache is trivial anyway) The main disadvantages of using MySql Have to define table templates every time I want to store provide a new set of grouped data. Have to write a program which loops through the correlated data and fills these new tables. Potentially will still grow slower as the data continues to be filled. Apologies for quite a long question. It's helped me to write down these thoughts here anyway, and any advice/help/experience with dealing with this sort of problem would be greatly appreciated. Many thanks. Alan

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  • Are indexes good or bad for a large database?

    - by gmemon
    Hello All, I read on MySQL Performance Blog that when tables are large, it is better to scan full tables, instead of using indexes. I have a table with tens of millions of rows. When conducting queries, if I use no indexes, then queries are 24 times slower than with indexes. I know lot of things may cause this (e.g., are rows stored sequentially), but can you please give me some hints what might be happening? Or how I should start examining this issue? I want to understand when use of indexes is preferred and when it's not Thanks

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  • Does the order of conditions in a WHERE clause affect MySQL performance?

    - by Greg
    Say that I have a long, expensive query, packed with conditions, searching a large number of rows. I also have one particular condition, like a company id, that will limit the number of rows that need to be searched considerably, narrowing it down to dozens from hundreds of thousands. Does make any difference to MySQL performance whether I do this: SELECT * FROM clients WHERE (firstname LIKE :foo OR lastname LIKE :foo OR phone LIKE :foo) AND (firstname LIKE :bar OR lastname LIKE :bar OR phone LIKE :bar) AND company = :ugh or this: SELECT * FROM clients WHERE company = :ugh AND (firstname LIKE :foo OR lastname LIKE :foo OR phone LIKE :foo) AND (firstname LIKE :bar OR lastname LIKE :bar OR phone LIKE :bar)

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  • Streaming large result sets with MySQL

    - by configurator
    I'm developing a spring application that uses large MySQL tables. When loading large tables, I get an OutOfMemoryException, since the driver tries to load the entire table into application memory. I tried using statement.setFetchSize(Integer.MIN_VALUE); but then every ResultSet I open hangs on close(); looking online I found that that happens because it tries loading any unread rows before closing the ResultSet, but that is not the case since I do this: ResultSet existingRecords = getTableData(tablename); try { while (existingRecords.next()) { // ... } } finally { existingRecords.close(); // this line is hanging, and there was no exception in the try clause } The hangs happen for small tables (3 rows) as well, and if I don't close the RecordSet (which happened in one method) then connection.close() hangs.

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  • hadoop - large database query

    - by Mastergeek
    Situation: I have a Postgres DB that contains a table with several million rows and I'm trying to query all of those rows for a MapReduce job. From the research I've done on DBInputFormat, Hadoop might try and use the same query again for a new mapper and since these queries take a considerable amount of time I'd like to prevent this in one of two ways that I've thought up: 1) Limit the job to only run 1 mapper that queries the whole table and call it good. or 2) Somehow incorporate an offset in the query so that if Hadoop does try to use a new mapper it won't grab the same stuff. I feel like option (1) seems more promising, but I don't know if such a configuration is possible. Option(2) sounds nice in theory but I have no idea how I would keep track of the mappers being made and if it is at all possible to detect that and reconfigure. Help is appreciated and I'm namely looking for a way to pull all of the DB table data and not have several of the same query running because that would be a waste of time.

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  • Would vector of vectors be contiguous?

    - by user1150989
    I need to allocate a vector of rows where row contains a vector of rows. I know that a vector would be contiguous. I wanted to know whether a vector of vectors would also be contiguous. Example code is given below vector<long> firstRow; firstRow.push_back(0); firstRow.push_back(1); vector<long> secondRow; secondRow.push_back(0); secondRow.push_back(1); vector< vector < long> > data; data.push_back(firstRow); data.push_back(secondRow); Would the sequence in memory be 0 1 0 1?

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  • MSSQL Sum query

    - by ldb
    today my problem is this i have 2 column and i wish check if the sum of that columns isn't Higher then a value(485 for example) and if is do a query...i though to do SELECT * FROM table WHERE ColumnA+ColumnB<485 But isn't working... i've already tried with SELECT Sum(ColumnA)+Sum(ColumnB) AS Total FROM table but it gives me 1 column with the sum of all rows, i instead want a row for every sum. so how can i do..? xD i hope you understood if not just ask that i try to explain it better! and thanks in advice for who want to help me! EDIT: I Found out XD the problem was that the columns was Smallint and the result of 1 or more rows was more than 32k so it wasn't working! Thanks At all!!

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  • Get all or part result from sql using one TSQL commnd

    - by Yongwei Xing
    Hi All Here is my condition. There is a Text box in a form, if you don't input any thing, it would return all rows in this table. If you input something, it would return rows whose Col1 matches the input. I try to use the sql below to do it. But there is one problem, these columns allows Null value. It wouldn't return the row with NULL value. Is there any way to return all or matched row based on the input? Col1 Col2 Col3 ABCD EDFR NULL NULL YUYY TTTT NULL KKKK DDDD select * from TABLE where Col1 like Coalesce('%'+@Col1Val+'%',[Col1])

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  • C# logic order and compiler behavior

    - by Terrapin
    In C#, (and feel free to answer for other languages), what order does the runtime evaluate a logic statement? Example: DataTable myDt = new DataTable(); if (myDt != null && myDt.Rows.Count > 0) { //do some stuff with myDt } Which statement does the runtime evaluate first - myDt != null or: myDt.Rows.Count > 0 ? Is there a time when the compiler would ever evaluate the statement backwards? Perhaps when an "OR" operator is involved?

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