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  • IN statement performance in PostgreSQL (and in general)

    - by Vasil
    I know this has probably been asked before, but I can't find it with SO's search. Lets say i've TABLE1 and TABLE2, who should I expect the performance of a query such as this: SELECT * FROM TABLE1 WHERE id IN SUBQUERY_ON_TABLE2; as the number of rows in TABLE1 and TABLE2 grow and id is a primary key on TABLE1. Yes, I know using IN is such a n00b mistake, but TABLE2 has a generic relation (django generic relation) to multiple other tables so I can't think of another way to filter the data. At what (aproximate) ammount of rows in TABLE1 and TABLE2 should I expect to notice performance issues because of this? Will performance degrade linearly, exponentially etc. depending on the number of rows?

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  • Indexing SET field

    - by Dienow
    I have two entities A and B. They are related with many to many relation. Entity A can be related up to 100 B entities. Entity B can be related up to 10000 A entities. I need quick way to select for example 30 A entities, that have relation with specified B entities, filtered and sorted by different attributes. Here how I see ideal solution: I put all information I know about A entities, including their relations with B entities into single row (Special table with SET field) then add all necessary indexes. The problem is that you can't use index while querying by SET field. What should I do? I can replace database with something different, if that'll help.

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  • Deadlock between select and truncate (postgresql)

    - by valodzka
    Table output_values_center1 (and some other) inherits output_values. Periodically I truncate table output_values_center1 and load new data (in one transaction). In that time user can request some data and he got error message. Why it ever happens (select query requests only one record) and how to avoid such problem: 2010-05-19 14:43:17 UTC ERROR: deadlock detected 2010-05-19 14:43:17 UTC DETAIL: Process 25972 waits for AccessShareLock on relation 2495092 of database 16385; blocked by process 26102. Process 26102 waits for AccessExclusiveLock on relation 2494865 of database 16385; blocked by process 25972. Process 25972: SELECT * FROM "output_values" WHERE ("output_values".id = 122312) LIMIT 1 Process 26102: TRUNCATE TABLE "output_values_center1"

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  • How to get attribute of a model saved in instance variable

    - by Nazar
    I am writing a plugin, in which i define a new relation dynamically with in plugin. Sample code is given below module AttachDocumentsAs @as = nil def attach_documents_as(*attachment_as) attachment_as = attachment_as.to_a.flatten.compact.map(&:to_sym) @as = attachment_as.first class_inheritable_reader(@as) class_eval do has_many @as, :as => :attachable, :class_name=>"AttachDocuments::Models::AttachedDocument" accepts_nested_attributes_for @as end end end now in any model i used it as class Person < AtiveRecord::Base attach_documents_as :financial_documents end Now want to access want to access this attribute of the class in overloaded initialize method like this def initialize(*args) super(*args) "#{@as}".build end But it is not getting required attribute, can any one help me in it. I want to build this relation and set some initial values. Waiting for guidelines from all you guys.

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  • What is the best design for these data base tables?

    - by Mohammed Jamal
    I need to find the best solution to make the DB Normalized with large amount of data expected. My site has a Table Tags (contain key word,id) and also 4 types of data related to this tags table like(articles,resources,jobs,...). The big question is:- for the relation with tags what best solution for optimazaion & query speed? make a table for each relation like: table articlesToTags(ArticleID,TagID) table jobsToTags(jobid,tagid) etc. or put it all in one table like table tagsrelation(tagid,itemid,itemtype) I need your help. Please provide me with articles to help me in this design consider that in future the site can conation new section relate to tag Thanks

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  • What to Expect in Rails 4

    - by mikhailov
    Rails 4 is nearly there, we should be ready before it released. Most developers are trying hard to keep their application on the edge. Must see resources: 1) @sikachu talk: What to Expect in Rails 4.0 - YouTube 2) Rails Guides release notes: http://edgeguides.rubyonrails.org/4_0_release_notes.html There is a mix of all major changes down here: ActionMailer changes excerpt: Asynchronously send messages via the Rails Raise an ActionView::MissingTemplate exception when no implicit template could be found ActionPack changes excerpt Added controller-level etag additions that will be part of the action etag computation Add automatic template digests to all CacheHelper#cache calls (originally spiked in the cache_digests plugin) Add Routing Concerns to declare common routes that can be reused inside others resources and routes Added ActionController::Live. Mix it in to your controller and you can stream data to the client live truncate now always returns an escaped HTML-safe string. The option :escape can be used as false to not escape the result Added ActionDispatch::SSL middleware that when included force all the requests to be under HTTPS protocol ActiveModel changes excerpt AM::Validation#validates ability to pass custom exception to :strict option Changed `AM::Serializers::JSON.include_root_in_json' default value to false. Now, AM Serializers and AR objects have the same default behaviour Added ActiveModel::Model, a mixin to make Ruby objects work with AP out of box Trim down Active Model API by removing valid? and errors.full_messages ActiveRecord changes excerpt Use native mysqldump command instead of structure_dump method when dumping the database structure to a sql file. Attribute predicate methods, such as article.title?, will now raise ActiveModel::MissingAttributeError if the attribute being queried for truthiness was not read from the database, instead of just returning false ActiveRecord::SessionStore has been extracted from Active Record as activerecord-session_store gem. Please read the README.md file on the gem for the usage Fix reset_counters when there are multiple belongs_to association with the same foreign key and one of them have a counter cache Raise ArgumentError if list of attributes to change is empty in update_all Add Relation#load. This method explicitly loads the records and then returns self Deprecated most of the 'dynamic finder' methods. All dynamic methods except for find_by_... and find_by_...! are deprecated Added ability to ActiveRecord::Relation#from to accept other ActiveRecord::Relation objects Remove IdentityMap ActiveSupport changes excerpt ERB::Util.html_escape now escapes single quotes ActiveSupport::Callbacks: deprecate monkey patch of object callbacks Replace deprecated memcache-client gem with dalli in ActiveSupport::Cache::MemCacheStore Object#try will now return nil instead of raise a NoMethodError if the receiving object does not implement the method, but you can still get the old behavior by using the new Object#try! Object#try can't call private methods Add ActiveSupport::Deprecations.behavior = :silence to completely ignore Rails runtime deprecations What are the most important changes for you?

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  • SQL Server many-to-many design recommendation

    - by Jean-Philippe Brabant
    I have a SQL Server database with two table : Users and Achievements. My users can have multiple achievements so it a many-to-many relation. At school we learned to create an associative table for that sort of relation. That mean creating a table with a UserID and an AchivementID. But if I have 500 users and 50 achievements that could lead to 25 000 row. As an alternative, I could add a binary field to my Users table. For example, if that field contained 10010 that would mean that this user unlocked the first and the fourth achievements. Is their other way ? And which one should I use.

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  • Javascript Library - Family Tree Flowchart

    - by MrMime
    Im looking for a simple Javascript Library (svg?) that allow me to draw a family tree relationships. I have searched a lot on google found a lot of interesting libraries like Raphaël and its extention Dracula. Google has its own library to make flowcharts too. Unfortunally, every library make a relation between nodes with a sigle line. If A and B has a relation to C, I will obtain 2 line: one from A to C and one from B to C. What I need is a line from A to B (we call it AB) and a line from AB to C to represent the Marriage of A and B. example-image Thanks.

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  • Save or update for FK relationship Sqlalchemy

    - by Alex
    I've googled, but haven't been able to find the answer to this seemingly simple question. I have two relations, a customer and an order. Each order is associated to a single cusomter, and therefore has a FK relationship to the customer table. The customer relation only stores customer names, and I have set a unique constraint on the customer table barring duplicate names. Let's say I create a new order instance and set a customer for the order. Something like: order_instance.customer = Customer("customer name") When I save the order instance, SqlAlchemy will complain if a customer with this name already exists in the customer table. How do I specify to SqlAlchemy to insert into the customer table if a customer with this name doesn't already exist, or just ignore (or even update) to the customer relation? I don't really want to have to check each time if a customer with some name already exists...

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  • Making a many-to-many relationship using DataRelations object

    - by dotnetdev
    Hi, I have about 200 tables which need to relate to another table in a many-to-many fashion. I have the tables (including the intersection table) ready IN SQL Server. How can I write code using the data relation object to make the relationship? The tables are: PartStatPartName PartsMaterialsIntersection << Materials The materials table needs to have a foreign key from the PartStatPartName table. I tried various approaches using the DataRelation class but the change did not sync to SQL Server, despite being connected and adding the relation, and then calling AcceptChanges() on the dataset. Any guidance much appreciated. I have seen some threads covering the same problem but need an example in code so I can follow the right method. Thanks

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  • Drupal Views: Render Null Result for Relationship as 0

    - by Kyle S
    I have a View configured in Drupal to return nodes, sorting them by their average vote in descending order. For the purpose of the View, the value of the average votes is a Relationship. I noticed that nodes with no votes are displayed after nodes with a negative average. Nodes with no votes should have an average of 0, but I believe the MySQL JOIN is causing NULL values to be returned (as there are no matching rows in the joined table, since a row is created after the first vote is cast for that item). I discovered that with MySQL it is possible to output all values that are NULL in a column as another value with IFNULL(column_name,'other value'). I feel like I would need to modify the Views module in order to obtain this functionality, but I'm hoping that there is some sort of option that returns NULL values in a relation (a relation doesn't exist for the item) as 0 instead of NULL, so that I can properly sort the nodes. The modules I am using include Views, Voting API, Vote Up/Down, and CTools. Thanks.

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  • If cookie found, get data, else create cookie, is this good logic?

    - by Ryan
    I have an Action that basically adds an item to a cart, the only way the cart is known is by checking the cookie, here is the flow of logic, please let me know if you see any issue... /order/add/[id] is called via GET action checks for cookie, if no cookie found, it makes a new cart, writes the identifier to the cookie, and adds the item to the database with a relation to the cart created if cookie is found, it gets the cart identifier from the cookie, gets the cart object, adds the item to the database with a relation to the cart found so it's basically like... action add(int id){ if(cookie is there) cart = getcart(cookievalue) else cart = makecart() createcookie(cart.id) additemtocart(cart.id, id) return "success"; } Seem right? I can't really thing of another way that would make sense.

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  • How to throttle email server wide on a shared server?

    - by fdsa
    I have multiple programs that send email on a shared server with a relatively low email limit. These programs are completely separate and can each individually throttle mail but cannot do so in relation to the others. Currently, whenever the hourly limit is reached, our host just starts dropping the emails. They say they have no way to change this behavior and basically suggested that I ask around. Does anyone know of any programs that will throttle email server wide on a shared server?

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  • Unstructured Data - The future of Data Administration

    Some have claimed that there is a problem with the way data is currently managed using the relational paradigm do to the rise of unstructured data in modern business. PCMag.com defines unstructured data as data that does not reside in a fixed location. They further explain that unstructured data refers to data in a free text form that is not bound to any specific structure. With the rise of unstructured data in the form of emails, spread sheets, images and documents the critics have a right to argue that the relational paradigm is not as effective as the object oriented data paradigm in managing this type of data. The relational paradigm relies heavily on structure and relationships in and between items of data. This type of paradigm works best in a relation database management system like Microsoft SQL, MySQL, and Oracle because data is forced to conform to a structure in the form of tables and relations can be derived from the existence of one or more tables. These critics also claim that database administrators have not kept up with reality because their primary focus in regards to data administration deals with structured data and the relational paradigm. The relational paradigm was developed in the 1970’s as a way to improve data management when compared to standard flat files. Little has changed since then, and modern database administrators need to know more than just how to handle structured data. That is why critics claim that today’s data professionals do not have the proper skills in order to store and maintain data for modern systems when compared to the skills of system designers, programmers , software engineers, and data designers  due to the industry trend of object oriented design and development. I think that they are wrong. I do not disagree that the industry is moving toward an object oriented approach to development with the potential to use more of an object oriented approach to data.   However, I think that it is business itself that is limiting database administrators from changing how data is stored because of the potential costs, and impact that might occur by altering any part of stored data. Furthermore, database administrators like all technology workers constantly are trying to improve their technical skills in order to excel in their job, so I think that accusing data professional is not just when the root cause of the lack of innovation is controlled by business, and it is business that will suffer for their inability to keep up with technology. One way for database professionals to better prepare for the future of database management is start working with data in the form of objects and so that they can extract data from the objects so that the stored information within objects can be used in relation to the data stored in a using the relational paradigm. Furthermore, I think the use of pattern matching will increase with the increased use of unstructured data because object can be selected, filtered and altered based on the existence of a pattern found within an object.

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  • Finding a person in the forest

    - by PointsToShare
    © 2011 By: Dov Trietsch. All rights reserved finding a person in the forest or Limiting the AD result in SharePoint People Picker There are times when we need to limit the SharePoint audience of certain farms or servers or site collections to a particular audience. One of my experiences involved limiting access to US citizens, another to a particular location. Now, most of us – your humble servant included – are not Active Directory experts – but we must be able to handle the “audience restrictions” as required. So here is how it’s done in a nutshell. Important note. Not all could be done in PowerShell (at least not yet)! There are no Windows PowerShell commands to configure People Picker. The stsadm command is: stsadm -o setproperty -pn peoplepicker-searchadcustomquery -pv ADQuery –url http://somethingOrOther Note the long-hyphenated property name. Now to filling the ADQuery.   LDAP Query in a nutshell Syntax LDAP is no older than SQL and an LDAP query is actually a query against the LDAP Database. LDAP attributes are the equivalent of Database columns, so why do we have to learn a new query language? Beats me! But we must, so here it is. The syntax of an LDAP query string is made of individual statements with relational operators including: = Equal <= Lower than or equal >= Greater than or equal… and memberOf – a group membership. ! Not * Wildcard Equal and memberOf are the most commonly used. Checking for absence uses the ! – not and the * - wildcard Example: (SN=Grant) All whose last name – SurName – is Grant Example: (!(SN=Grant)) All except Grant Example: (!(SN=*)) all where there is no SurName i.e SurName is absent (probably Rappers). Example: (CN=MyGroup) Common Name is MyGroup.  Example: (GN=J*) all the Given Names that start with J (JJ, Jane, Jon, John, etc.) The cryptic SN, CN, GN, etc. are attributes and more about them later All the queries are enclosed in parentheses (Query). Complex queries are comprised of sets that are in AND or OR conditions. AND is denoted by the ampersand (&) and the OR is denoted by the vertical pipe (|). The general syntax is that of the Prefix polish notation where the operand precedes the variables. E.g +ab is the sum of a and b. In an LDAP query (&(A)(B)) will garner the objects for which both A and B are true. In an LDAP query (&(A)(B)(C)) will garner the objects for which A, B and C are true. There’s no limit to the number of conditions. In an LDAP query (|(A)(B)) will garner the objects for which either A or B are true. In an LDAP query (|(A)(B)(C)) will garner the objects for which at least one of A, B and C is true. There’s no limit to the number of conditions. More complex queries have both types of conditions and the parentheses determine the order of operations. Attributes Now let’s get into the SN, CN, GN, and other attributes of the query SN – is the SurName (last name) GN – is the Given Name (first name) CN – is the Common Name, usually GN followed by SN OU – is an Organization Unit such as division, department etc. DC – is a Domain Content in the AD forest l – lower case ‘L’ stands for location. Jerusalem anybody? Or Katmandu. UPN – User Principal Name, is usually the first part of an email address. By nature it is unique in the forest. Most systems set the UPN to be the first initial followed by the SN of the person involved. Some limit the total to 8 characters. If we have many ‘jsmith’ we have to somehow distinguish them from each other. DN – is the distinguished name – a name unique to AD forest in which it lives. Usually it’s a CN with some domain or group distinguishers. DN is important in conjunction with the memberOf relation. Groups have stricter requirement. Each group has to have a unique name - its CN and it has to be unique regardless of its place. See more below. All of the attributes are case insensitive. CN, cn, Cn, and cN are identical. objectCategory is an element that requires special consideration. AD contains many different object like computers, printers, and of course people and groups. In the queries below, we’re limiting our search to people (person). Putting it altogether Let’s get a list of all the Johns in the SPAdmin group of the Jerusalem that local domain. (&(objectCategory=person)(memberOf=cn=SPAdmin,ou=Jerusalem,dc=local)) The memberOf=cn=SPAdmin uses the cn (Common Name) of the SPAdmin group. This is how the memberOf relation is used. ‘SPAdmin’ is actually the DN of the group. Also the memberOf relation does not allow wild cards (*) in the group name. Also, you are limited to at most one ‘OU’ entry. Let’s add Marvin Minsky to the search above. |(&(objectCategory=person)(memberOf=cn=SPAdmin,ou=Jerusalem,dc=local))(CN=Marvin Minsky) Here I added the or pipeline at the beginning of the query and put the CN requirement for Minsky at the end. Note that if Marvin was already in the prior result, he’s not going to be listed twice. One last note: You may see a dryer but more complete list of attributes rules and examples in: http://www.tek-tips.com/faqs.cfm?fid=5667 And finally (thus negating the claim that my previous note was last), to the best of my knowledge there are 3 more ways to limit the audience. One is to use the peoplepicker-searchadcustomfilter property using the same ADQuery. This works only in SP1 and above. The second is to limit the search to users within this particular site collection – the property name is peoplepicker-onlysearchwithinsitecollection and the value is yes (-pv yes) And the third is –pn peoplepicker-serviceaccountdirectorypaths –pv “OU=ou1,DC=dc1…..” Again you are limited to at most one ‘OU’ phrase – no OU=ou1,OU=ou2… And now the real end. The main property discussed in this sprawling and seemingly endless monogram – peoplepicker-searchadcustomquery - is the most general way of getting the job done. Here are a few examples of command lines that worked and some that didn’t. Can you see why? C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\BIN>stsa dm -o setproperty -url http://somethingOrOther -pn peoplepicker-searchadcustomfi lter -pv (Title=David) Operation completed successfully. C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\BIN>stsa dm -o setproperty -url http://somethingOrOther -pn peoplepicker-searchadcustomfi lter -pv (!Title=David) Operation completed successfully. C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\BIN>stsa dm -o setproperty -url http://somethingOrOther -pn peoplepicker-searchadcustomfi lter -pv (OU=OURealName,OU=OUMid,OU=OUTop,DC=TopDC,DC=MidDC,DC=BottomDC) Command line error. Too many OUs C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\BIN>stsa dm -o setproperty -url http://somethingOrOther -pn peoplepicker-searchadcustomfi lter -pv (OU=OURealName) Operation completed successfully. C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\BIN>stsa dm -o setproperty -url http://somethingOrOther -pn peoplepicker-searchadcustomfi lter -pv (DC=TopDC,DC=MidDC,DC=BottomDC) Operation completed successfully. C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\BIN>stsa dm -o setproperty -url http://somethingOrOther -pn peoplepicker-searchadcustomfi lter -pv (OU=OURealName,DC=TopDC,DC=MidDC,DC=BottomDC) Operation completed successfully.   That’s all folks!

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  • An XEvent a Day (27 of 31) – The Future - Tracking Page Splits in SQL Server Denali CTP1

    - by Jonathan Kehayias
    Nearly two years ago Kalen Delaney blogged about Splitting a page into multiple pages , showing how page splits occur inside of SQL Server.  Following her blog post, Michael Zilberstein wrote a post, Monitoring Page Splits with Extended Events , that showed how to see the sqlserver.page_split Events using Extended Events.  Eladio Rincón also blogged about Using XEvents (Extended Events) in SQL Server 2008 to detect which queries are causing Page Splits , but not in relation to Kalen’s blog...(read more)

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  • Keyword Research - Why Bother?

    "Every long journey, starts with a single step" says Confucius. And with every successful SEO campaign, one must start with proper keyword research. Keyword research is more than just knowing which keywords to use for a campaign, it also determines the direction of your campaign in relation to whatever key phrase you are targeting.

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  • « Les DSI utiliseront plus astucieusement l'informatique en 2012 » d'après Oracle, qui prévoit une progression des CRM

    « Les DSI utiliseront plus astucieusement l'informatique en 2012 » D'après Oracle, qui prévoit une progression des CRM Pour préparer l'avenir, « les DSI utiliseront plus astucieusement l'informatique en 2012 ». Telle est l'une des conclusions tirées par Oracle de l'étude que la société a commanditée à PwC Cette étude révèle que les priorités des fournisseurs de services de télécommunication pour 2012 sont de rechercher un meilleur équilibre entre l'informatique interne et l'externalisation, et de mieux utiliser des applications telles que la gestion de la relation clients (CRM) Concrètement, le rapport montre que 60% des DSI consacrent actuellement plus de la ...

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  • Bill Gates et Mark Zuckerberg vont enseigner la programmation à travers l'initiative Code.org

    Bill Gates et Zuckerberg rejoignent la campagne Hour of code une initiative de code.org destinée à apprendre la programmation aux plus jeunesLa moisson est abondante pour le vaste marché de l'emploi aux États-Unis, mais les ouvriers sont peu nombreux. Le « Bureau of Labor Statistics » américain estime que les années à venir devraient donner naissance à près de 122 000 opportunités d'emploi en relation avec l'informatique. La condition requise pour postuler à ces offres sera d'avoir au minimum...

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  • Hosted CRM Solutions from a Manager?s Perspective

    CRM, Customer Relationship Management is a method or process that is used to know the customer?s behavior and their needs and it helps in developing a stronger relation with them. This is only a defi... [Author: James Wong - Computers and Internet - April 29, 2010]

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  • OOP - Composition, Components and Composites Example?

    - by coder3
    I've been reading a bit about OOP in relation to Composition, Components and Composites. I believe I understand the fundamental principle (not sure). Can some one please provide a code example of a person or car (both have many properties) using Composition, Components and Composites. I think seeing it in code would clear up the confusion I have regarding this pattern. Preferably in Java or PHP - many thanks!

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  • Parallel Data Warehouse

    - by jchang
    The Microsoft Parallel Data Warehouse diagram was somewhat difficult to understand in terms of the functionality of each subsystem in relation to the configuration of its components. So now that HP has provided a detailed list of the PDW components , the diagram below shows the PDW subsystems with component configuration (InfiniBand, FC, and network connections not shown). Observe that there are three different ProLiant server models, the DL360 G7, DL370 G6 and the DL380 G7, in five different configurations...(read more)

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