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  • "Thread was being aborted" 0n large dataset

    - by Donaldinio
    I am trying to process 114,000 rows in a dataset (populated from an oracle database). I am hitting an error at around the 600 mark - "Thread was being aborted". All I am doing is reading the dataset, and I still hit the issue. Is this too much data for a dataset? It seems to load into the dataset ok though. I welcome any better ways to process this amount of data. rootTermsTable = entKw.GetRootKeywordsByCategory(catID); for (int k = 0; k < rootTermsTable.Rows.Count; k++) { string keywordID = rootTermsTable.Rows[k]["IK_DBKEY"].ToString(); ... } public DataTable GetKeywordsByCategory(string categoryID) { DbProviderFactory provider = DbProviderFactories.GetFactory(connectionProvider); DbConnection con = provider.CreateConnection(); con.ConnectionString = connectionString; DbCommand com = provider.CreateCommand(); com.Connection = con; com.CommandText = string.Format("Select * From icm_keyword WHERE (IK_IC_DBKEY = {0})",categoryID); com.CommandType = CommandType.Text; DataSet ds = new DataSet(); DbDataAdapter ad = provider.CreateDataAdapter(); ad.SelectCommand = com; con.Open(); ad.Fill(ds); con.Close(); DataTable dt = new DataTable(); dt = ds.Tables[0]; return dt; //return ds.Tables[0].DefaultView; }

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  • Reduce durability in MySQL for performance

    - by Paul Prescod
    My site occasionally has fairly predictable bursts of traffic that increase the throughput by 100 times more than normal. For example, we are going to be featured on a television show, and I expect in the hour after the show, I'll get more than 100 times more traffic than normal. My understanding is that MySQL (InnoDB) generally keeps my data in a bunch of different places: RAM Buffers commitlog binary log actual tables All of the above places on my DB slave This is too much "durability" given that I'm on an EC2 node and most of the stuff goes across the same network pipe (file systems are network attached). Plus the drives are just slow. The data is not high value and I'd rather take a small chance of a few minutes of data loss rather than have a high probability of an outage when the crowd arrives. During these traffic bursts I would like to do all of that I/O only if I can afford it. I'd like to just keep as much in RAM as possible (I have a fair chunk of RAM compared to the data size that would be touched over an hour). If buffers get scarce, or the I/O channel is not too overloaded, then sure, I'd like things to go to the commitlog or binary log to be sent to the slave. If, and only if, the I/O channel is not overloaded, I'd like to write back to the actual tables. In other words, I'd like MySQL/InnoDB to use a "write back" cache algorithm rather than a "write through" cache algorithm. Can I convince it to do that? If this is not possible, I am interested in general MySQL write-performance optimization tips. Most of the docs are about optimizing read performance, but when I get a crowd of users, I am creating accounts for all of them, so that's a write-heavy workload.

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  • Table index design

    - by Swoosh
    I would like to add index(s) to my table. I am looking for general ideas how to add more indexes to a table. Other than the PK clustered. I would like to know what to look for when I am doing this. So, my example: This table (let's call it TASK table) is going to be the biggest table of the whole application. Expecting millions records. IMPORTANT: massive bulk-insert is adding data in this table table has 27 columns: (so far, and counting :D ) int x 9 columns = id-s varchar x 10 columns bit x 2 columns datetime x 5 columns INT COLUMNS all of these are INT ID-s but from tables that are usually smaller than Task table (10-50 records max), example: Status table (with values like "open", "closed") or Priority table (with values like "important", "not so important", "normal") there is also a column like "parent-ID" (self - ID) join: all the "small" tables have PK, the usual way ... clustered STRING COLUMNS there is a (Company) column (string!) that is something like "5 characters long all the time" and every user will be restricted using this one. If in Task there are 15 different "Companies" the logged in user would only see one. So there's always a filter on this one. Might be a good idea to add an index to this column? DATE COLUMNS I think they don't index these ... right? Or can / should be?

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  • Why represent shopping carts and order invoices differently in a domain model?

    - by Todd
    I've built some shopping cart systems in the past, but I always designed them such that the final order invoice is just a shopping cart that has been marked as "purchased". All the logic for adding/removing/changing items in a cart is also the logic for the order. All data is stored in the same tables in the database. But it seems this is not the proper way to design an e-commerce site.. Can someone explain the benefit of separating the shopping cart from invoices in the domain model? It seems to me this would lead to a lot of duplicated code, an extra set of tables in the database, and make it harder to maintain in the event the system need to start accommodating more complicated orders (like specifying selected options for an item which may or may not change the price/availability/shipping time of the order). I'm assuming I just haven't seen the light, as every book and other example I see seems to separate these two seemingly similar concerns -- but I can't find any explanation as to the benefit of doing such! It's also the case in the systems that I design that changes are often made after the initial order is confirmed. It's not uncommon for items to be removed, replaced, or added afterwards (but prior to fulfillment).

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  • reporting tool/viewer for large datasets

    - by FrustratedWithFormsDesigner
    I have a data processing system that generates very large reports on the data it processes. By "large" I mean that a "small" execution of this system produces about 30 MB of reporting data when dumped into a CSV file and a large dataset is about 130-150 MB (I'm sure someone out there has a bigger idea of "large" but that's not the point... ;) Excel has the ideal interface for the report consumers in the form of its Data Lists: users can filter and segment the data on-the-fly to see the specific details that they are interested in - they can also add notes and markup to the reports, create charts, graphs, etc... They know how to do all this and it's much easier to let them do it if we just give them the data. Excel was great for the small test datasets, but it cannot handle these large ones. Does anyone know of a tool that can provide a similar interface as Excel data lists, but that can handle much larger files? The next tool I tried was MS Access, and found that the Access file bloats hugely (30 MB input file leads to about 70 MB Access file, and when I open the file, run a report and close it the file's at 120-150 MB!), the import process is slow and very manual (currently, the CSV files are created by the same plsql script that runs the main process so there's next to no intervention on my part). I also tried an Access database with linked tables to the database tables that store the report data and that was many times slower (for some reason, sqlplus could query and generate the report file in a minute or soe while Access would take anywhere from 2-5 minutes for the same data) (If it helps, the data processing system is written in PL/SQL and runs on Oracle 10g.)

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  • C#: Using one Data Table in order to fill 2 different comboboxes?

    - by odiseh
    Hi all. I have 2 comboboxes on a form (form1) called combobox1 and combobox2. Each comboboxes should be filled with data stored in 2 different tables in Sql server 2005: table1 and table2 I mean: combobox1 -- table1 combobox2 -- table2 I fill data table with proper data and then bind the comboboxes to it separately. My problem is: after filling 2 combos, both of them have equal data got from table2. This is my code: DataTable tb1 = new DataTable(); //Filling tb1 with data got from table1 combobox1.Items.Clear(); combobox1.DataSource = tb1; combobox1.DisplayMember = "Name"; combobox1.ValueMember = "ID"; combobox1.SelectedIndex = -1; //filling tb1 with data got from table2 combobox2.Items.Clear(); combobox2.DataSource = tb1; combobox2.DisplayMember = "Name"; combobox2.ValueMember = "ID"; combobox2.SelectedIndex = -1; What's wrong? It seems that if I get 2 different data tables (tb1 and tb2) , every thing will be all right. Any suggestions please. Thank you

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  • Sql Server Replication: Snapshot vs Merge

    - by Zyphrax
    Background information Let's say I have two database servers, both SQL Server 2008. One is in my LAN (ServerLocal), the other one is on a remote hosting environment (ServerRemote). I have created a database on ServerLocal and have an exact copy of that database on ServerRemote. The database on ServerRemote is part of a web application and I would like to keep it's data up-to-date with the data in the database ServerLocal. ServerLocal is able to communicate with ServerRemote, this is one-way traffic. Communication from ServerRemote to ServerLocal isn't available. Current solution I thought it would be a nice solution to use replication. So I've made ServerLocal a publisher and subscriptions are pushed to the ServerRemote. This works fine, when a snapshot is transfered to ServerRemote the existing data will be purged and the ServerRemote database is once again an exact replica of the database on ServerLocal. The problem Records that exist on ServerRemote that don't exist on ServerLocal are removed. This doesn't matter for most of my tables but in some of my tables I'd like to keep the existing data (aspnet_users for instance), and update the records if necessary. What kind of replication fits my problem?

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  • many to many relationship mysql select

    - by zeina
    Let's consider 2 tables "schools" and "students". Now a student may belong to different schools in his life, and a school have many students. So this is a many to many example. A third table "links" specify the relation between student and school. Now to query this I do the following: Select sc.sid , -- stands for school id st.uid, -- stands for student id sc.sname, -- stands for school name st.uname, -- stands for student name -- select more data about the student joining other tables for that from students s left join links l on l.uid=st.uid -- l.uid stands for the student id on the links table left join schools sc on sc.sid=l.sid -- l.sid is the id of the school in the links table where st.uid=3 -- 3 is an example this query will return duplicate data for the user id if he has more than one school, so to fix this I added group by st.uid, yet I also need the list of school name related to the same user. Is there a way to do it with fixing the query I wrote instead of having 2 queries? So as example I want to have Luci of schools ( X, Y, Z, R, ...) etc

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  • Update Options on Existing jQuery Object

    - by Vince Kronlein
    I'm using Bootstrap and DataTables in my app and I have a default initializer for tables based on class. I can just add the class data-table to the table and it gets instantiated with the default values I want. I'd like to know how to change or update specific options based on a specific table. if ($.fn.dataTable) { $('.data-table').dataTable( { sDom: "R<'row'<'span6'l><'span6'f>r>t<'row'<'span6'i><'span6'p>>", sPaginationType: "bootstrap", oLanguage: { "sLengthMenu": "_MENU_ &nbsp; records per page" }, aoColumnDefs: [ { "bSortable": false, "aTargets": [ 0 ] } ] }); } All my data tables have a checkbox in the first column so the above removal of sorting works for all of them. But I'd like to be able to update the aoColumnDefs on a table by table basis so I can add other columns that I don't want sorted. So let's say I have a table: $('#member-list'), how do I access this object and update it's datatables options in jQuery? I can't find any reference or help anywhere. Thanks a lot! -V

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  • How would you organize this in asp.net mvc?

    - by chobo
    I have an asp.net mvc 2.0 application that contains Areas/Modules like calendar, admin, etc... There may be cases where more than one area needs to access the same Repo, so I am not sure where to put the Data Access Layers and Repositories. First Option: Should I create Data Access Layer files (Linq to SQL in my case) with their accompanying Repositories for each area, so each area only contains the Tables, and Repositories needed by those areas. The benefit is that everything needed to run that module is one place, so it is more encapsulated (in my mind anyway). The downside is that I may have duplicate queries, because other modules may use the same query. Second Option Or, would it be better to place the DAL and Repositories outside the Area's and treat them as Global? The advantage is I won't have any duplicate queries, but I may be loading a lot of unnecessary queries and DAL tables up for certain modules. It is also more work to reuse or modify these modules for future projects (though the chance of reusing them is slim to none :)) Which option makes more sense? If someone has a better way I'd love to hear it. Thanks!

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  • How can I manage a FIFO-queue in an database with SQL?

    - by Jonas
    I have two tables in my database, one for In and one for Out. They have two columns, Quantity and Price. How can I write a SQL-query that selects the correct price? In example: If I have 3 items in for 75 and then 3 items in for 80. Then I have two out for 75, and the third out should be for 75 (X) and the fourth out should be for 80 (Y). How can I write the price query for X and Y? They should use the price from the third and forth row. In example, is there any way to SELECT the third row in the In-table? I can not use auto_increment as identifier for i.e. "third" row, because the tables will contain post for other items too. The rows will not be deleted, they will be saved for accountability reasons. SELECT Price FROM In WHERE ...? NEW database design: +----+ | In | +----+------+-------+ | Supply_ID | Price | +-----------+-------+ | 1 | 75 | | 1 | 75 | | 1 | 75 | | 2 | 80 | | 2 | 80 | +-----------+-------+ +-----+ | Out | +-----+-------+-------+ | Delivery_ID | Price | +-------------+-------+ | 1 | 75 | | 1 | 75 | | 2 | X | <- ? | 3 | Y | <- ? +-------------+-------+ OLD database design: +----+ | In | +----+------+----------+-------+ | Supply_ID | Quantity | Price | +-----------+----------+-------+ | 1 | 3 | 75 | | 2 | 3 | 80 | +-----------+----------+-------+ +-----+ | Out | +-----+-------+----------+-------+ | Delivery_ID | Quantity | Price | +-------------+----------+-------+ | 1 | 2 | 75 | | 2 | 1 | X | <- ? | 3 | 1 | Y | <- ? +-------------+----------+-------+

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  • T4 trouble compiling transformation

    - by John Leidegren
    I can't figure this one out. Why doesn't T4 locate the IEnumerable type? I'm using Visual Studio 2010. And I just hope someone knows why? <#@ template debug="true" hostspecific="false" language="C#" #> <#@ assembly name="System.Data, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" #> <#@ import namespace="System" #> <#@ import namespace="System.Data" #> <#@ import namespace="System.Data.SqlClient" #> <#@ output extension=".cs" #> public static class Tables { <# var q = @" SELECT tbl.name 'table', col.name 'column' FROM sys.tables tbl INNER JOIN sys.columns col ON col.object_id = tbl.object_id "; // var source = Execute(q); #> } <#+ static IEnumerable Execute(string cmdText) { using (var conn = new SqlConnection(@"Data Source=.\SQLEXPRESS;Initial Catalog=t4build;Integrated Security=True;")) { conn.Open(); var cmd = new SqlCommand(cmdText, conn); using (var reader = cmd.ExecuteReader()) { while (reader.Read()) { } } } } #> Error 2 Compiling transformation: The type or namespace name 'IEnumerable' could not be found (are you missing a using directive or an assembly reference?) c:\Projects\T4BuildApp\T4BuildApp\TextTemplate1.tt 26 9

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  • The Impossible Layout?

    - by Kyle K
    I'm beginning to think this is impossible, but thought I'd ask you guys. Basically it's a 2 column layout, but the "business" wants the following: -Always take up the entire browser window -Accommodate resizing of browser window -Left column will be fixed width, but that width should be flexible from page-to-page. -Left column has a region at the top with fixed height. -Left column has a bottom region. It should take up the remaining vertical space of browser window. If content is very large, it will have a scroll bar just for that region. -Right column should take up remaining horizontal space of browser window. -Right column has a region at the top with fixed height. -Right column has a bottom region. It should take up the remaining vertical space of browser window. If content is very large, it will have a scroll bar just for that region. I've tried everything...divs, floated, absolutely positioned, tables, divs in tables... Is this even possible? Here's an image of what it should look like: http://imgur.com/zk1jP.png

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  • SQL Server 2008 - Full Text Query

    - by user208662
    Hello, I have two tables in a SQL Server 2008 database in my company. The first table represents the products that my company sells. The second table contains the product manufacturer’s details. These tables are defined as follows: Product ------- ID Name ManufacturerID Description Manufacturer ------------ ID Name As you can imagine, I want to make this as easy as possible for our customers to query this data. However, I’m having problems writing a forgiving, yet powerful search query. For instance, I’m anticipating people to search based on phonetical spellings. Because of this, the data may not match the exact data in my database. In addition, I think some individuals will search by manufacturer’s name first, but I want the matching product names to appear first. Based on these requirements, I’m currently working on the following query: select p.Name as 'ProductName', m.Name as 'Manufacturer', r.Rank as 'Rank' from Product p inner join Manufacturer m on p.ManufacturerID=m.ID inner join CONTAINSTABLE(Product, Name, @searchQuery) as r Oddly, this query is throwing an error. However, I have no idea why. Squiggles appear to the right of the last parenthesis in management studio. The tool tip says "An expression of non-boolean type specified in a context where a condition is expected". I understand what this statement means. However, I guess I do not know how COntainsTable works. What am I doing wrong? Thank you

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  • Select rows from table1 and all the children from table2 into an object

    - by Patrick
    I want to pull data from table "Province_Notifiers" and also fetch all corresponding items from table "Province_Notifier_Datas". The table "Province_Notifier" has a guid to identify it (PK), table "Province_Notifier_Datas" has a column called BelongsToProvinceID witch is a foreign key to the "Province_Notifier" tables guid. I tried something like this: var records = from data in ctx.Province_Notifiers where DateTime.Now >= data.SendTime && data.Sent == false join data2 in ctx.Province_Notifier_Datas on data.Province_ID equals data2.BelongsToProvince_ID select new Province_Notifier { Email = data.Email, Province_ID = data.Province_ID, ProvinceName = data.ProvinceName, Sent = data.Sent, UserName = data.UserName, User_ID = data.User_ID, Province_Notifier_Datas = (new List<Province_Notifier_Data>().AddRange(data2)) }; This line is not working and i am trying to figure out how topull the data from table2 into that Province_Notifier_Datas variable. Province_Notifier_Datas = (new List<Province_Notifier_Data>().AddRange(data2)) I can add a record easily by adding the second table row into the Province_Notifier_Datas but i can't fetch it back. Province_Notifier dbNotifier = new Province_Notifier(); // set some values for dbNotifier dbNotifier.Province_Notifier_Datas.Add( new Province_Notifier_Data { BelongsToProvince_ID = userInput.Value.ProvinceId, EventText = GenerateNotificationDetail(notifierDetail) }); This works and inserts the data correctly into both tables. Edit: These error messages is thrown: Cannot convert from 'Province_Notifier_Data' to 'System.Collections.Generic.IEnumerable' If i look in Visual Studio, the variable "Province_Notifier_Datas" is of type System.Data.Linq.EntitySet The best overloaded method match for 'System.Collections.Generic.List.AddRange(System.Collections.Generic.IEnumerable)' has some invalid arguments Edit: var records = from data in ctx.Province_Notifiers where DateTime.Now >= data.SendTime && data.Sent == false join data2 in ctx.Province_Notifier_Datas on data.Province_ID equals data2.BelongsToProvince_ID into data2list select new Province_Notifier { Email = data.Email, Province_ID = data.Province_ID, ProvinceName = data.ProvinceName, Sent = data.Sent, UserName = data.UserName, User_ID = data.User_ID, Province_Notifier_Datas = new EntitySet<Province_Notifier_Data>().AddRange(data2List) }; Error 3 The name 'data2List' does not exist in the current context.

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  • Where should my "filtering" logic reside with Linq-2-SQL and ASP.NET-MVC in View or Controller?

    - by Nate Bross
    I have a main Table, with several "child" tables. TableA and TableAChild1 and TableAChild2. I have a view which shows the information in TableA, and then has two columns of all items in TableAChild1 and TableAChild2 respectivly, they are rendered with Partial views. Both child tables have a bit field for VisibleToAll, and depending on user role, I'd like to either display all related rows, or related rows where VisibleToAll = true. This code, feels like it should be in the controller, but I'm not sure how it would look, because as it stands, the controller (limmited version) looks like this: return View("TableADetailView", repos.GetTableA(id)); Would something like this be even work, and would it be bad what if my DataContext gets submitted, would that delete all the rows that have VisibleToAll == false? var tblA = repos.GetTableA(id); tblA.TableAChild1 = tblA.TableAChild1.Where(tmp => tmp.VisibleToAll == true); tblA.TableAChild2 = tblA.TableAChild2.Where(tmp => tmp.VisibleToAll == true); return View("TableADetailView", tblA); It would also be simple to add that logic to the RendarPartial call from the main view: <% Html.RenderPartial("TableAChild1", Model.TableAChild1.Where(tmp => tmp.VisibleToAll == true); %>

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  • Use a foreign key mapping to get data from the other table using Python and SQLAlchemy.

    - by Az
    Hmm, the title was harder to formulate than I thought. Basically, I've got these simple classes mapped to tables, using SQLAlchemy. I know they're missing a few items but those aren't essential for highlighting the problem. class Customer(object): def __init__(self, uid, name, email): self.uid = uid self.name = name self.email = email def __repr__(self): return str(self) def __str__(self): return "Cust: %s, Name: %s (Email: %s)" %(self.uid, self.name, self.email) The above is basically a simple customer with an id, name and an email address. class Order(object): def __init__(self, item_id, item_name, customer): self.item_id = item_id self.item_name = item_name self.customer = None def __repr__(self): return str(self) def __str__(self): return "Item ID %s: %s, has been ordered by customer no. %s" %(self.item_id, self.item_name, self.customer) This is the Orders class that just holds the order information: an id, a name and a reference to a customer. It's initialised to None to indicate that this item doesn't have a customer yet. The code's job will assign the item a customer. The following code maps these classes to respective database tables. # SQLAlchemy database transmutation engine = create_engine('sqlite:///:memory:', echo=False) metadata = MetaData() customers_table = Table('customers', metadata, Column('uid', Integer, primary_key=True), Column('name', String), Column('email', String) ) orders_table = Table('orders', metadata, Column('item_id', Integer, primary_key=True), Column('item_name', String), Column('customer', Integer, ForeignKey('customers.uid')) ) metadata.create_all(engine) mapper(Customer, customers_table) mapper(Orders, orders_table) Now if I do something like: for order in session.query(Order): print order I can get a list of orders in this form: Item ID 1001: MX4000 Laser Mouse, has been ordered by customer no. 12 What I want to do is find out customer 12's name and email address (which is why I used the ForeignKey into the Customer table). How would I go about it?

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  • How can manage a FIFO-queue in an database with SQL?

    - by Jonas
    I have two tables in my database, one for In and one for Out. They have two columns, Quantity and Price. How can I write a SQL-query that selects the correct price? In example: If I have 3 items in for 75 and then 3 items in for 80. Then I have two out for 75, and the third out should be for 75 (X) and the fourth out should be for 80 (Y). How can I write the price query for X and Y? They should use the price from the third and forth row. In example, is there any way to SELECT the third row in the In-table? I can not use auto_increment as identifier for i.e. "third" row, because the tables will contain post for other items too. The rows will not be deleted, they will be saved for accountability reasons. SELECT Price FROM In WHERE ...? NEW database design: +----+ | In | +----+------+-------+ | Supply_ID | Price | +-----------+-------+ | 1 | 75 | | 1 | 75 | | 1 | 75 | | 2 | 80 | | 2 | 80 | +-----------+-------+ +-----+ | Out | +-----+-------+-------+ | Delivery_ID | Price | +-------------+-------+ | 1 | 75 | | 1 | 75 | | 2 | X | <- ? | 3 | Y | <- ? +-------------+-------+ OLD database design: +----+ | In | +----+------+----------+-------+ | Supply_ID | Quantity | Price | +-----------+----------+-------+ | 1 | 3 | 75 | | 2 | 3 | 80 | +-----------+----------+-------+ +-----+ | Out | +-----+-------+----------+-------+ | Delivery_ID | Quantity | Price | +-------------+----------+-------+ | 1 | 2 | 75 | | 2 | 1 | X | <- ? | 3 | 1 | Y | <- ? +-------------+----------+-------+

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  • Sub Query making Query slow.

    - by Muhammad Kashif Nadeem
    Please copy and paste following script. DECLARE @MainTable TABLE(MainTablePkId int) INSERT INTO @MainTable SELECT 1 INSERT INTO @MainTable SELECT 2 DECLARE @SomeTable TABLE(SomeIdPk int, MainTablePkId int, ViewedTime1 datetime) INSERT INTO @SomeTable SELECT 1, 1, DATEADD(dd, -10, getdate()) INSERT INTO @SomeTable SELECT 2, 1, DATEADD(dd, -9, getdate()) INSERT INTO @SomeTable SELECT 3, 2, DATEADD(dd, -6, getdate()) DECLARE @SomeTableDetail TABLE(DetailIdPk int, SomeIdPk int, Viewed INT, ViewedTimeDetail datetime) INSERT INTO @SomeTableDetail SELECT 1, 1, 1, DATEADD(dd, -7, getdate()) INSERT INTO @SomeTableDetail SELECT 2, 2, NULL, DATEADD(dd, -6, getdate()) INSERT INTO @SomeTableDetail SELECT 3, 2, 2, DATEADD(dd, -8, getdate()) INSERT INTO @SomeTableDetail SELECT 4, 3, 1, DATEADD(dd, -6, getdate()) SELECT m.MainTablePkId, (SELECT COUNT(Viewed) FROM @SomeTableDetail), (SELECT TOP 1 s2.ViewedTimeDetail FROM @SomeTableDetail s2 INNER JOIN @SomeTable s1 ON s2.SomeIdPk = s1.SomeIdPk WHERE s1.MainTablePkId = m.MainTablePkId) FROM @MainTable m Above given script is just sample. I have long list of columns in SELECT and around 12+ columns in Sub Query. In my From clause there are around 8 tables. To fetch 2000 records full query take 21 seconds and if I remove Subquiries it just take 4 seconds. I have tried to optimize query using 'Database Engine Tuning Advisor' and on adding new advised indexes and statistics but these changes make query time even bad. Note: As I have mentioned that this is test data to explain my question the real data has lot of tables joins columns but without Sub-Query the results us fine. Any help thanks.

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  • Why would using a Temp table be faster than a nested query?

    - by Mongus Pong
    We are trying to optimise some of our queries. One query is doing the following: SELECT t.TaskID, t.Name as Task, '' as Tracker, t.ClientID, (<complex subquery>) Date, INTO [#Gadget] FROM task t SELECT TOP 500 TaskID, Task, Tracker, ClientID, dbo.GetClientDisplayName(ClientID) as Client FROM [#Gadget] order by CASE WHEN Date IS NULL THEN 1 ELSE 0 END , Date ASC DROP TABLE [#Gadget] (I have removed the complex subquery, cos I dont think its relevant other than to explain why this query has been done as a two stage process.) Now I would have thought it would be far more efficient to merge this down into a single query using subqueries as : SELECT TOP 500 TaskID, Task, Tracker, ClientID, dbo.GetClientDisplayName(ClientID) FROM ( SELECT t.TaskID, t.Name as Task, '' as Tracker, t.ClientID, (<complex subquery>) Date, FROM task t ) as sub order by CASE WHEN Date IS NULL THEN 1 ELSE 0 END , Date ASC This would give the optimiser better information to work out what was going on and avoid any temporary tables. It should be faster. But it turns out it is a lot slower. 8 seconds vs under 5 seconds. I cant work out why this would be the case as all my knowledge of databases imply that subqueries would always be faster than using temporary tables. Can anyone explain what could be going on!?!?

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  • ExecuteNonQuery: Connection property has not been initialized

    - by 20151012
    I get an error in my code: The error point at dbcom.ExecuteNonQuery();. Code(connection) public admin_addemp() { InitializeComponent(); con = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=|DataDirectory|\EMPS.accdb;Persist Security Info=True"); con.Open(); ds.Tables.Add(dt); ds.Tables.Add(dt2); } Code (Save button) private void save_btn_Click(object sender, EventArgs e) { OleDbCommand check = new OleDbCommand(); check.Connection = con; check.CommandText = "SELECT COUNT(*) FROM employeeDB WHERE ([EmployeeName]=?)"; check.Parameters.AddWithValue("@EmployeeName", tb_name.Text); if (Convert.ToInt32(check.ExecuteScalar()) == 0) { dbcom2 = new OleDbCommand("SELECT EmployeeID FROM employeeDB WHERE EmployeeID='" + tb_id.Text + "'", con); OleDbParameter param = new OleDbParameter(); param.ParameterName = tb_id.Text; dbcom.Parameters.Add(param); OleDbDataReader read = dbcom2.ExecuteReader(); if (read.HasRows) { MessageBox.Show("The Employee ID '" + tb_id.Text + "' already exist. Please choose another Employee ID."); read.Dispose(); read.Close(); } else { string q = "INSERT INTO employeeDB (EmployeeID, EmployeeName, IC, Address, State, " + " Postcode, DateHired, Phone, ManagerName) VALUES ('" + tb_id.Text + "', " + " '" + tb_name.Text + "', '" + tb_ic.Text + "', '" + tb_add1.Text + "', '" + cb_state.Text + "', " + " '" + tb_postcode.Text + "', '" + dateTimePicker1.Value + "', '" + tb_hp.Text + "', '" + cb_manager.Text + "')"; dbcom = new OleDbCommand(q, con); dbcom.ExecuteNonQuery(); MessageBox.Show("New Employee '" + tb_name.Text + "'- Successfuly Added."); } } else { MessageBox.Show("Employee name '" + tb_name.Text + "' already added into the database"); } ds.Dispose(); } I'm using Microsoft Access 2010 as my database and this is stand alone system. Please help me.

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  • SQL Compact performance on device

    - by Ben M
    My SQL Compact database is very simple, with just three tables and a single index on one of the tables (the table with 200k rows; the other two have less than a hundred each). The first time the .sdf file is used by my Compact Framework application on the target Windows Mobile device, the system hangs for well over a minute while "something" is done to the database: when deployed, the DB is 17 megabytes, and after this first usage, it balloons to 24 megs. All subsequent usage is pretty fast, so I'm assuming there's some sort of initialization / index building going on during this first usage. I'd rather not subject the user to this delay, so I'm wondering what this initialization process is and whether it can be performed before deployment. For now, I've copied the "initialized" database back to my desktop for use in the setup project, but I'd really like to have a better answer / solution. I've tried "full compact / repair" in the VS Database Properties dialog, but this made no difference. Any ideas? For the record, I should add that the database is only read from by the device application -- no modifications are made by that code.

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  • What are the hibernate annotations used to persist a Map with an enumerated type as a key?

    - by Jason Novak
    I am having trouble getting the right hibernate annotations to use on a Map with an enumerated class as a key. Here is a simplified (and extremely contrived) example. public class Thing { public String id; public Letter startLetter; public Map<Letter,Double> letterCounts = new HashMap<Letter, Double>(); } public enum Letter { A, B, C, D } Here are my current annotations on Thing @Entity public class Thing { @Id public String id; @Enumerated(EnumType.STRING) public Letter startLetter; @CollectionOfElements @JoinTable(name = "Thing_letterFrequencies", joinColumns = @JoinColumn(name = "thingId")) @MapKey(columns = @Column(name = "letter", nullable = false)) @Column(name = "count") public Map<Letter,Double> letterCounts = new HashMap<Letter, Double>(); } Hibernate generates the following DDL to create the tables for my MySql database create table Thing (id varchar(255) not null, startLetter varchar(255), primary key (id)) type=InnoDB; create table Thing_letterFrequencies (thingId varchar(255) not null, count double precision, letter tinyblob not null, primary key (thingId, letter)) type=InnoDB; Notice that hibernate tries to define letter (my map key) as a tinyblob, however it defines startLetter as a varchar(255) even though both are of the enumerated type Letter. When I try to create the tables I see the following error BLOB/TEXT column 'letter' used in key specification without a key length I googled this error and it appears that MySql has issues when you try to make a tinyblob column part of a primary key, which is what hibernate needs to do with the Thing_letterFrequencies table. So I would rather have letter mapped to a varchar(255) the way startLetter is. Unfortunately, I've been fussing with the MapKey annotation for a while now and haven't been able to make this work. I've also tried @MapKeyManyToMany(targetEntity=Product.class) without success. Can anyone tell me what are the correct annotations for my letterCounts map so that hibernate will treat the letterCounts map key the same way it does startLetter?

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  • Python modules, classs, functions documentation through Sphinx

    - by user343934
    Hi everyone, I am trying to document my small project through sphinx which im recently trying to get familiar with. I read some tutorials and sphinx documentation but couldn't make it. Setup and configurations are ok! just have problems in using sphinx in a technical way. My table of content should look like this --- Overview .....Contents ----Configuration ....Contents ---- System Requirements .....Contents ---- How to use .....Contents ---- Modules ..... Index ......Display ----Help ......Content Moreover my focus is on Modules with docstrings. Details of Modules are Directory:- c:/wamp/www/project/ ----- Index.py >> Class HtmlTemplate: .... def header(): .... def body(): .... def form(): .... def header(): .... __init_main: ----- display.py >> Class MainDisplay: .... def execute(): .... def display(): .... def tree(): .... __init_main: My Documentation Directory:- c:/users/abc/Desktop/Documentation/doc/ --- _build --- _static --- _templates --- conf.py --- index.rst I have added Modules directory to the system environment and edited index.rst with following codes Welcome to Seq-alignment's documentation! Contents: .. toctree:: :maxdepth: 2 .. automodule:: index.py .. autoclass:: HtmlTemplate :members:Header,Body,Form,Footer,CloseHtml .. automodule:: display.py .. autoclass:: MainDisplay :members:execute,display,tree Indices and tables :ref:genindex :ref:modindex :ref:search When i make html file and view it, apparently i dont get Modules in the content tables but just there is show record and when i click it just i get "index.txt" version in another window. I need your suggestions Thanks

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  • Performance of inter-database query (between linked servers)

    - by Swoosh
    I have an import between 2 linked servers. I basically got to get the data from a multiple join into a table on my side. The current query is something like this: select a.* from db1.dbo.tbl1 a inner join db1.dbo.tbl2 on ... inner join db1.dbo.tbl3 on ... inner join db1.dbo.tbl4 on ... inner join db2.dbo.myside on ... db1 = linked server db2 = my own database After this one, I am using an insert into + select to add this data in my table which is located in db2. (usually few hundred records - this import running once a minute) My question is related to performance. The tables on the linked server (tbl1, tbl2, tbl3, tbl4) are huge tables, with millions of records, and it is slowing down the import process. I was told that, if I do the join on the "other" side (db1 - linked server) for example in a stored procedure, than, even if the query looks the same, it would run faster. Is that right? This is kinda hard to test. Note that the join contains a table from my database too. Also. are there other "tricks" I could use in order to make this run faster? Thanks

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