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  • How to write custom data to the TCP packet header options field with Java?

    - by snarkov
    As it is defined (see: http://www.freesoft.org/CIE/Course/Section4/8.htm) the TCP header has an 'Options' field. There are a couple of options already defined (see: www.iana.org/assignments/tcp-parameters/) but I want to come up with my very own. (For experimenting/research.) How can I get Java to write (and then read) some custom data to the options field? Bonus question: if it cannot be done with Java. what kind of application can do this? (No, I don't really feel like messing with some kernel-level TCP/IP stack implementation, I want to keep it app level.) Thanks!

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  • What data type should I use for my texture coordinates in OpenGL ES?

    - by Matthew Chen
    I notice that the default data type for texture coordinates in the OpenGL docs is GLfloat, but much of the sample code I see written by experienced iphone developers uses GLshort or GLbyte. Is this an optimization? GLfloat vertices[] = { // Upper left x1, y2, // Lower left x1, y1, // Lower right x2, y1, // Upper right x2, y2, }; glTexCoordPointer(2, GL_FLOAT, 0, iconSTs); vs. GLbyte vertices[] = { // Upper left x1, y2, // Lower left x1, y1, // Lower right x2, y1, // Upper right x2, y2, }; glTexCoordPointer(2, GL_BYTE, 0, iconSTs);

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  • Django many-to-many relationship to self with extra data, how do I select from a certain direction?

    - by Jake
    I have some hierarchical data where each Set can have many members and can belong to more than one Set(group) Here are the models: class Set(models.Model): ... groups = models.ManyToManyField('self', through='Membership', symmetrical=False) members = models.ManyToManyField('self', through='Membership', symmetrical=False) class Membership(models.Model): group = models.ForeignKey( Set, related_name='Members' ) member = models.ForeignKey( Set, related_name='Groups' ) order = models.IntegerField( default=-1 ) I want to know how to get all the members or all the groups for a Set instance. I think I can do it as follows, but it's not very logical, can anyone tell me what's going on and how I should be doing it? # This gives me a set of Sets # Which seems to be the groups this Set belongs to set_instance.set_set.all() # These give me a set of Memberships, not Sets set_instance.Members.all() set_instance.Groups.all() # These they both return a set of Sets # which seem to be the members of this one set_instance.members.all() set_instance.groups.all()

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  • string parsing help

    - by sprugman
    I've got a string like this: #################### Section One #################### Data A Data B #################### Section Two #################### Data C Data D etc. I want to parse it into something like: $arr( 'Section One' => array('Data A', 'Data B'), 'Section Two' => array('Data C', 'Data D') ) At first I tried this: $sections = preg_split("/(\r?\n)(\r?\n)#/", $file_content); The problem is, the file isn't perfectly clean: sometimes there are different numbers of blank lines between the sections, or blank spaces between data rows. The section head pattern itself seems to be relatively consistent: #################### Section Title #################### The number of #'s is probably consistent, but I don't want to count on it. The white space on the title line is pretty random. Once I have it split into sections, I think it'll be pretty straightforward, but any help writing a killer reg ex to get it there would be appreciated. (Or if there's a better approach than reg ex...)

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  • How can i show delete image in each row in a Data grid ?

    - by developer
    i want show a image onmouse over inside data grid to each row,so if i click on that image,some function should call(as per my requirement). how can i do this ? <mx:DataGrid width="320" height="624" verticalScrollPolicy="on" dataProvider="{blocked_Usernames}" editable="true"> <mx:columns> <mx:DataGridColumn headerText="Blocked User Name" dataField="blockedUsernames" editorDataField="value"/> <mx:DataGridColumn width="20" editable="false"> <mx:itemRenderer > <mx:Component > <mx:Image source="@Embed('assets/image/Close.png')" width="10" height="10" autoLoad="false"/> </mx:Component> </mx:itemRenderer> </mx:DataGridColumn> </mx:columns> </mx:DataGrid>

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  • Building a wiki like data model in rails question.

    - by lillq
    I have a data model in which I would like to have an item that has a description that can be edited. I would like to also keep track of all edits to the item. I am running into issues with my current strategy, which is: class Item < ActiveRecord::Base has_one :current_edit, :class_name => "Edit", :foreign_key => "current_edit_id" has_many :edits end class Edit < ActiveRecord::Base belongs_to :item end Can the Item have multiple associations to the same class like this? I was thinking that I should switch to keeping track of the edit version in the Edit object and then just sorting the has_many relationship base on this version.

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  • Looking for framework for plotting scientific data: 2d/3d ...

    - by Ivan
    I need to visualize some scientific calculations. I generally prefer reusing code if there is already a good available instead of inventing wheels each time, that's why I am asking. I need a C# code to draw charts (just outputting a bitmap is ok) of 2d (y=f(x)) and 3d (z=f(x,y)) digital data sets (where any axis can be float, int or datetime), sometimes combined. If I go here and click 3D in the navigation bar on the left, there I can see what I need. But the cheapest version costs $759 there, looks scary for a hobby project of an east-european student :-(

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  • How can I use linq to build an object from 1 row of data?

    - by Hcabnettek
    Hi All, I have a quick linq question. I have a stored proc that should return one row of data. I would like to use a lambda to build an object. Here's what I'm currently doing which works, but I know I should be able to use First instead of Select except I can't seem to get the syntax correct. Can anyone straighten me out here? Thanks for any help. var location = new GeoLocationDC(); DataSet ds = db.ExecuteDataSet(dbCommand); if(ds.Tables[0].Rows.Count == 1) { var rows = ds.Tables[0].AsEnumerable(); var x = rows.Select( c => new GeoLocationDC { Latitude = Convert.ToInt32(c.Field<string>("LATITUDE")), Longitude = Convert.ToInt32(c.Field<string>("LONGITUDE")) }).ToList(); if(x.Count > 0 ) { location = x[0]; } Cheers, ~ck }

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  • How do I use BCP or Sql Server Management Studio to get BLOB data our of Sql Server?

    - by Eric
    I'm sorry if this question has been asked already, but I couldn't find it anywhere. I have a table that stores files as BLOBS. The column that holds the file is an image datatype. I would like to be able to extract the binary data out of the column and turn it in to an actual file. I would ideally like to be able to do this with BCP or management studio if possible. I have tried BCP, but for some reason when I try and pull out an office document Word thinks it's corrupt. Here's what I've tried so far (obviously the values have been changed to protect the innocent :): bcp "select document_binary_data from database where id = 12345" queryout "c:\filename.doc" -n -S server -U username -P password This isn't working though? Any thoughts?

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  • Loading a datagrid with large amounts of data in silverlight?

    - by JD
    Hi I am breaking up my project in small sections and one of the sections involves loading a grid with possibily lots of records (could be up to 1000s of records in the database). Ideally I would like some sort of mechanism where as the users scrolls the grid, more data is retrieved. I have read that certain controls (datapager with RIA) do this but I would like to know how I could implement this myself or do something similiar? I was thinking about first loading 50 records at a time and when the user gets to scroll near the 50th record, then get another 50 as a start and so on. Not sure how I do this but this does not feel right or whether I should load ids of records in the grid and then get each row to load itself via an async thread but then I am hitting my database for each record? Thanks JD.

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  • Whats the best data-structure for storing 2-tuple (a, b) which support adding, deleting tuples and c

    - by bhups
    Hi So here is my problem. I want to store 2-tuple (key, val) and want to perform following operations: - keys are strings and values are Integers - multiple keys can have same value - adding new tuples - updating any key with new value (any new value or updated value is greater than the previous one, like timestamps) - fetching all the keys with values less than or greater than given value - deleting tuples. Hash seems to be the obvious choice for updating the key's value but then lookups via values will be going to take longer (O(n)). The other option is balanced binary search tree with key and value switched. So now lookups via values will be fast (O(lg(n))) but updating a key will take (O(n)). So is there any data-structure which can be used to address these issues? Thanks.

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  • How can i store data in C in a tabular format?

    - by aks
    Hi, I want to store data in C in tabular format. I am having difficulty in relating the following. Can someone help? For example: I want to store the follwong entries, then what should be the ideal way of storing in C? IP Address Domain Name 1.) 10.1.1.2 www.yahoo.com 2.) 20.1.1.3 www.google.com Should i use structures? Say for example? struct table { unsigned char ip address; char domain_name[20]; }; If not, please clarify?

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  • MVVM where does the code to load the data belong?

    - by cody
    As I wrap my head around the mvvm thing, the view is the view, and the viewmodel is 'a modal of a view' and the model are the entities we are dealing with (or at least that is my understanding). But I'm unclear as to what and when the model entities are populated. So for example: Lets say I have app that needs to create a new record in a DB. And that record should have default values to start with. Who is responsible for the new record, and getting the default values. Does this have anything to do with MVVM or is that part of a data access layer? Who calls the the viewmodel? Or for existing records when\where are the records retrieved? And saved if altered? Thanks

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  • Can I configure a strongly typed data set to use nullable values?

    - by Dan Tao
    If I have a strongly typed data table with a column for values of type Int32, and this column allows nulls, then I'll get an exception if I do this for a row where the value is null: int value = row.CustomValue; Instead I need to do this: if (!row.IsCustomValueNull()) { int value = row.CustomValue; // do something with this value } Ideally I would like to be able to do this: int? value = row.CustomValue; Of course I could always write my own method, something like GetCustomValueOrNull; but it'd be preferable if the property auto-generated for the column itself simply returned a nullable. Is this possible?

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  • How to use group by for grouping varchar data.

    - by Shantanu Gupta
    I have a table that contains some data given below pk_map_id preferences ImmediateParent Department_Id -------------------- -------------------- -------------------- -------------------- 20 14 5 1 21 15 5 1 22 16 6 1 23 9 4 2 24 4 3 2 25 24 20 2 26 25 20 2 27 23 13 2 I want to group my records on behalf of department then immediate parent then preferences each seperated by ',' i.e. department Immediate Parent preferences 1 5,6 14,15,16 2 4,3,20,13 9,4,24,25,23 and this table also Immediate parent preferences 5 14,15 6 16 4 9 3 4 20 24,25 13 13 In actual scenario all these are my ids which are to be replaced by their string fields. I am using sql server 2k5

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  • Creating a new plugin for mpld3

    - by sjp14051
    Toward learning how to create a new mpld3 plugin, I took an existing example, LinkedDataPlugin (http://mpld3.github.io/examples/heart_path.html), and modified it slightly by deleting references to lines object. That is, I created the following: class DragPlugin(plugins.PluginBase): JAVASCRIPT = r""" mpld3.register_plugin("drag", DragPlugin); DragPlugin.prototype = Object.create(mpld3.Plugin.prototype); DragPlugin.prototype.constructor = DragPlugin; DragPlugin.prototype.requiredProps = ["idpts", "idpatch"]; DragPlugin.prototype.defaultProps = {} function DragPlugin(fig, props){ mpld3.Plugin.call(this, fig, props); }; DragPlugin.prototype.draw = function(){ var patchobj = mpld3.get_element(this.props.idpatch, this.fig); var ptsobj = mpld3.get_element(this.props.idpts, this.fig); var drag = d3.behavior.drag() .origin(function(d) { return {x:ptsobj.ax.x(d[0]), y:ptsobj.ax.y(d[1])}; }) .on("dragstart", dragstarted) .on("drag", dragged) .on("dragend", dragended); patchobj.path.attr("d", patchobj.datafunc(ptsobj.offsets, patchobj.pathcodes)); patchobj.data = ptsobj.offsets; ptsobj.elements() .data(ptsobj.offsets) .style("cursor", "default") .call(drag); function dragstarted(d) { d3.event.sourceEvent.stopPropagation(); d3.select(this).classed("dragging", true); } function dragged(d, i) { d[0] = ptsobj.ax.x.invert(d3.event.x); d[1] = ptsobj.ax.y.invert(d3.event.y); d3.select(this) .attr("transform", "translate(" + [d3.event.x,d3.event.y] + ")"); patchobj.path.attr("d", patchobj.datafunc(ptsobj.offsets, patchobj.pathcodes)); } function dragended(d, i) { d3.select(this).classed("dragging", false); } } mpld3.register_plugin("drag", DragPlugin); """ def __init__(self, points, patch): print "Points ID : ", utils.get_id(points) self.dict_ = {"type": "drag", "idpts": utils.get_id(points), "idpatch": utils.get_id(patch)} However, when I try to link the plugin to a figure, as in plugins.connect(fig, DragPlugin(points[0], patch)) I get an error, 'module' is not callable, pointing to this line. What does this mean and why doesn't it work? Thanks. I'm adding additional code to show that linking more than one Plugin might be problematic. But this may be entirely due to some silly mistake on my part, or there is a way around it. The following code based on LinkedViewPlugin generates three panels, in which the top and the bottom panel are supposed to be identical. Mouseover in the middle panel was expected to control the display in the top and bottom panels, but updates occur in the bottom panel only. It would be nice to be able to figure out how to reflect the changes in multiple panels. Thanks. import matplotlib import matplotlib.pyplot as plt import numpy as np import mpld3 from mpld3 import plugins, utils class LinkedView(plugins.PluginBase): """A simple plugin showing how multiple axes can be linked""" JAVASCRIPT = """ mpld3.register_plugin("linkedview", LinkedViewPlugin); LinkedViewPlugin.prototype = Object.create(mpld3.Plugin.prototype); LinkedViewPlugin.prototype.constructor = LinkedViewPlugin; LinkedViewPlugin.prototype.requiredProps = ["idpts", "idline", "data"]; LinkedViewPlugin.prototype.defaultProps = {} function LinkedViewPlugin(fig, props){ mpld3.Plugin.call(this, fig, props); }; LinkedViewPlugin.prototype.draw = function(){ var pts = mpld3.get_element(this.props.idpts); var line = mpld3.get_element(this.props.idline); var data = this.props.data; function mouseover(d, i){ line.data = data[i]; line.elements().transition() .attr("d", line.datafunc(line.data)) .style("stroke", this.style.fill); } pts.elements().on("mouseover", mouseover); }; """ def __init__(self, points, line, linedata): if isinstance(points, matplotlib.lines.Line2D): suffix = "pts" else: suffix = None self.dict_ = {"type": "linkedview", "idpts": utils.get_id(points, suffix), "idline": utils.get_id(line), "data": linedata} class LinkedView2(plugins.PluginBase): """A simple plugin showing how multiple axes can be linked""" JAVASCRIPT = """ mpld3.register_plugin("linkedview", LinkedViewPlugin2); LinkedViewPlugin2.prototype = Object.create(mpld3.Plugin.prototype); LinkedViewPlugin2.prototype.constructor = LinkedViewPlugin2; LinkedViewPlugin2.prototype.requiredProps = ["idpts", "idline", "data"]; LinkedViewPlugin2.prototype.defaultProps = {} function LinkedViewPlugin2(fig, props){ mpld3.Plugin.call(this, fig, props); }; LinkedViewPlugin2.prototype.draw = function(){ var pts = mpld3.get_element(this.props.idpts); var line = mpld3.get_element(this.props.idline); var data = this.props.data; function mouseover(d, i){ line.data = data[i]; line.elements().transition() .attr("d", line.datafunc(line.data)) .style("stroke", this.style.fill); } pts.elements().on("mouseover", mouseover); }; """ def __init__(self, points, line, linedata): if isinstance(points, matplotlib.lines.Line2D): suffix = "pts" else: suffix = None self.dict_ = {"type": "linkedview", "idpts": utils.get_id(points, suffix), "idline": utils.get_id(line), "data": linedata} fig, ax = plt.subplots(3) # scatter periods and amplitudes np.random.seed(0) P = 0.2 + np.random.random(size=20) A = np.random.random(size=20) x = np.linspace(0, 10, 100) data = np.array([[x, Ai * np.sin(x / Pi)] for (Ai, Pi) in zip(A, P)]) points = ax[1].scatter(P, A, c=P + A, s=200, alpha=0.5) ax[1].set_xlabel('Period') ax[1].set_ylabel('Amplitude') # create the line object lines = ax[0].plot(x, 0 * x, '-w', lw=3, alpha=0.5) ax[0].set_ylim(-1, 1) ax[0].set_title("Hover over points to see lines") linedata = data.transpose(0, 2, 1).tolist() plugins.connect(fig, LinkedView(points, lines[0], linedata)) # second set of lines exactly the same but in a different panel lines2 = ax[2].plot(x, 0 * x, '-w', lw=3, alpha=0.5) ax[2].set_ylim(-1, 1) ax[2].set_title("Hover over points to see lines #2") plugins.connect(fig, LinkedView2(points, lines2[0], linedata)) mpld3.show()

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  • How to read data from SharePoint list using View RSS feeds to external site?

    - by James123
    I want export data from SharePoint lists (discussion forums, documents library, calendar) information to external site using RSS. Right now our SharePoint sites built on FBA based, so all sites are behind login page. Now I export each updates from these lists to our another external public site (anonymous). I know we have default View RSS Feed option. But that is not working for all readers like Google Reader, etc. Is there any free developer (open source) tool supports in this? Please share some ideas.

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  • What data is actually stored in a B-tree database in CouchDB?

    - by Andrey Vlasovskikh
    I'm wondering what is actually stored in a CouchDB database B-tree? The CouchDB: The Definitive Guide tells that a database B-tree is used for append-only operations and that a database is stored in a single B-tree (besides per-view B-trees). So I guess the data items that are appended to the database file are revisions of documents, not the whole documents: +---------|### ... | | +------|###|------+ ... ---+ | | | | +------+ +------+ +------+ +------+ | doc1 | | doc2 | | doc1 | ... | doc1 | | rev1 | | rev1 | | rev2 | | rev7 | +------+ +------+ +------+ +------+ Is it true? If it is true, then how the current revision of a document is determined based on such a B-tree? Doesn't it mean, that CouchDB needs a separate "view" database for indexing current revisions of documents to preserve O(log n) access? Wouldn't it lead to race conditions while building such an index? (as far as I know, CouchDB uses no write locks).

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  • Multiple Producers Single Consumer Queue

    - by Talguy
    I am new to multithreading and have designed a program that receives data from two microcontroller measuring various temperatures (Ambient and Water) and draws the data to the screen. Right now the program is singly threaded and its performance SUCKS A BIG ONE. I get basic design approaches with multithreading but not well enough to create a thread to do a task but what I don't get is how to get threads to perform seperate task and place the data into a shared data pool. I figured that I need to make a queue that has one consumer and multiple producers (would like to use std::queue). I have seen some code on the gtkmm threading docs that show a single Con/Pro queue and they would lock the queue object produce data and signal the sleeping thread that it is finished then the producer would sleep. For what I need would I need to sleep a thread, would there be data conflicts if i didn't sleep any of the threads, and would sleeping a thread cause a data signifcant data delay (I need realtime data to be drawn 30 frames a sec) How would I go about coding such a queue using the gtkmm/glibmm library.

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  • Build a decision tree for classification of large amount data,using python?

    - by kaushik
    Hi,i am working for speech synthesis.In this i have a large number of pronunciation for each phone i.e alphabet and need to classify them according to few feature such as segment size(int) and alphabet itself(string) into a smaller set suitable for that particular context. For this purpose,i have decided to use decision tree for classification.the data to be parsed is in the S expression format.eg:((question)(LEFTNODE)(RIGHTNODE)). i hav idea for building decision tree for normal buit in type such as list..looking for suggestion for implementation for S expression.. kindly help.. Thanks in advance.. Note:this question may look similar to my prev post,srry if cant giv multiple post.already edited it many times so though of wirting new question instead of editing again

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  • Data access strategy for a site like SO - sorted SQL queries and simultaneous updates that affect th

    - by Kaleb Brasee
    I'm working on a Grails web app that would be similar in access patterns to StackOverflow or MyLifeIsAverage - users can vote on entries, and their votes are used to sort a list of entries based on the number of votes. Votes can be placed while the sorted select queries are being performed. Since the selects would lock a large portion of the table, it seems that normal transaction locking would cause updates to take forever (given enough traffic). Has anyone worked on an app with a data access pattern such as this, and if so, did you find a way to allow these updates and selects to happen more or less concurrently? Does anyone know how sites like SO approach this? My thought was to make the sorted selects dirty reads, since it is acceptable if they're not completely up to date all of the time. This is my only idea for possibly improving performance of these selects and updates, but I thought someone might know a better way.

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  • Are memory barriers necessary for atomic reference counting shared immutable data?

    - by Dietrich Epp
    I have some immutable data structures that I would like to manage using reference counts, sharing them across threads on an SMP system. Here's what the release code looks like: void avocado_release(struct avocado *p) { if (atomic_dec(p->refcount) == 0) { free(p->pit); free(p->juicy_innards); free(p); } } Does atomic_dec need a memory barrier in it? If so, what kind of memory barrier? Additional notes: The application must run on PowerPC and x86, so any processor-specific information is welcomed. I already know about the GCC atomic builtins. As for immutability, the refcount is the only field that changes over the duration of the object.

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  • Import module stored in a cStringIO data structure vs. physical disk file

    - by Malcolm
    Is there a way to import a Python module stored in a cStringIO data structure vs. physical disk file? It looks like "imp.load_compiled(name, pathname[, file])" is what I need, but the description of this method (and similar methods) has the following disclaimer: Quote: "The file argument is the byte-compiled code file, open for reading in binary mode, from the beginning. It must currently be a real file object, not a user-defined class emulating a file." [1] I tried using a cStringIO object vs. a real file object, but the help documentation is correct - only a real file object can be used. Any ideas on why these modules would impose such a restriction or is this just an historical artifact? Are there any techniques I can use to avoid this physical file requirement? Thanks, Malcolm [1] http://docs.python.org/library/imp.html#imp.load_module

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  • Error while coping datacolumn with data from one table to another .

    - by Harikrishna
    I have one Datatable like DataTable addressAndPhones; And there are four columns name,address,phoneno,and other details and I only want two columns Name and address from that so I do for that is DataTable addressAndPhones2; addressAndPhones2.Columns.Add(new DataColumn(addressAndPhones.Columns["name"].ColumnName)); addressAndPhones2.Columns.Add(new DataColumn(addressAndPhones.Columns["address"].ColumnName)); But it gives me error so how can I copy fix no of columns data from one table to another table ? ERROR :Object reference not set to an instance of an object.

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  • Is the time cost constant when bulk inserting data into an indexed table?

    - by SiLent SoNG
    I have created an archive table which will store data for selecting only. Daily there will be a program to transfer a batch of records into the archive table. There are several columns which are indexed; while others are not. I am concerned with time cost per batch insertion: - 1st batch insertion: N1 - 2nd batch insertion: N2 - 3rd batch insertion: N3 The question is: will N1, N2, and N3 roughly be the same, or N3 N2 N1? That is, will the time cost be a constant or incremental, with existence of several indexes? All indexes are non-clustered. The archive table structure is this: create table document ( doc_id int unsigned primary key, owner_id int, -- indexed title smalltext, country char(2), year year(4), time datetime, key ix_owner(owner_id) }

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