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• How to preserve data integrity while minimizing the transmission size

  - by user1500578

  we have sensors in the wild that send their data to a server every day via TCP/IP, either through 3G or through satellite for the physical layer. The sensors can automatically switch from one to the other depending on their location and the quality of the signal with the local 3G operator. Given that the 3G and satellite communications are very expensive, we want to minimize the amount of data to send. But also, we want to protect ourselves from lost data. What would be the best strategy to ensure with reasonable certainty that the integrity of our data is preserved, while minimizing the amount of redundancy, i.e the amount of data transmitted ? I've read about the zfec codec, but I'm not sure if we need to transmit all the chunks, or if we need to send a hash code along each chunk.

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• DB2 Integrity Checks and Exception Tables

  - by imthefirestartr

  I am working on planning a migration of a DB2 8.1 database from a horrible IBM encoding to UTF-8 to support further languages etc. I am encountering an issue that I am stuck on. A few notes on this migration: We are using db2move to export and load the data and db2look to get the details fo the database (tablespaces, tables, keys etc). We found the loading process worked nicely with db2move import, however, the data takes 7 hours to load and this was unacceptable downtime when we actually complete the conversion on the main database. We are now using db2move load, which is much faster as it seems to simply throw the data in without integrity checks. Which leads to my current issue. After completing the db2move load process, several tables are in a check pending state and require integrity checks. Integrity checks are done via the following: set integrity for . immediate checked This works for most tables, however, some tables give an error: DB21034E The command was processed as an SQL statement because it was not a valid Command Line Processor command. During SQL processing it returned: SQL3603N Check data processing through the SET INTEGRITY statement has found integrity violation involving a constraint with name "blah.SQL120124110232400". SQLSTATE=23514 The internets tell me that the solution to this issue is to create an exception table based on the actual table and tell the SET INTEGRITY command to send any exceptions to that table (as below): db2 create table blah_EXCEPTION like blah db2 SET INTEGRITY FOR blah IMMEDIATE CHECKED FOR EXCEPTION IN blah USE blah_EXCEPTION NOW, here is the specific issue I am having! The above forces all the rows with issues to the specified exception table. Well that's just super, buuuuuut I can not lose data in this conversion, its simply unacceptable. The internets and IBM has a vague description of sending the violations to the exception tables and then "dealing with the data" that is in the exception table. Unfortunately, I am not clear what this means and I was hoping that some wise individual knows and could help me out and let me know how I can retrieve this data from these tables and place the data in the original/proper table rather than these exception tables. Let me know if you have any questions. Thanks!

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• How to copy files from HDD to HDD with integrity checking

  - by RafaelM

  I am moving data from an almost dead HDD to an external USB drive using linux , because for some reason Windows cannot see the data. I want to copy a large amount of data over from the HDD to the USB drive with integrity checking. I thought about copying everything over and then checking with md5summer but this would take a reaally long time because its a lot of data and this is not a very powerful PC. What tool can use to do this on Linux?

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• When is referential integrity not appropriate?

  - by Curtis Inderwiesche

  I understand the need to have referential integrity for limiting specific values on entry or possibly preventing them from removal upon a request of deletion. However, I am unclear as to a valid use case which would exclude this mechanism from always being used. I guess this would fall into several sub-questions: When is referential integrity not appropriate? Is it appropriate to have fields containing multiple and/or possibly incomplete subsets of a foreign key's list? Typically, should this be a schema structure design decision or an interface design decision? (Or possibly neither or both) Thoughts?

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• Database triggers / referential integrity and in-memory caching

  - by Ran Biron

  Do you see database triggers / referential integrity rules being used in a way that changes actual data in the database (changing row w in table x causes a change in row y in table z)? If yes, How does this tie-in with the increasing popularity of in-memory caching (memcache and friends)? After all, these actions occur inside the database but the caching system must be aware of them in order to reflect to correct state (or at least invalidate the possibly changed state). I find it hard to believe that callbacks are implemented for such cases. Does anyone have real-world experience with such a setup / real-world experience with considering such a setup and abandoning it (which way did you go? if caching, how do you enforce integrity?)

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• Normalization of database for timesheet tool and ensure data integrity

  - by fireeyedboy

  I'm creating a timesheet application. I have the following entities (amongst others): Company Employee = an employee associated with a company Client = a client associated with a company So far I have the following (abbreviated) database setup: Company - id - name Employee - id - companyId (FK to Company.id) - name Client - id - companyId (FK to Company.id) - name Now, I want an employee to be associated with a client, but only if that client is associated with the company the employee works for. How would you guarantee this data integrity on a database level? Or should I just depend on the application to guarantee this data integrity? I thought about creating a many to many table like this: EmployeeClient - employeeId (FK to Employee.id) - companyId \ (combined FK to Client.companyId, Client.id) - clientId / Thus, when I insert a client for an employee along with the employee's company id, the database should prevent this when the client is not associated with the employee's company id. Does this make sense? Because this still doesn't guarantee the employee is associated with the company. How do you deal with these things? UPDATE The scenario is as followed: A company has multiple employees. Employees will only be linked to one company. A company has multiple clients also. Clients will only be linked to one company. (Company is a sandbox, so to speak). An employee of a company can be linked to a client of it's company, but only if the client is part of the company's clientele. In other words: The application will allow a company to create/add employees and create/add clients (hence the companyId FK in the Employee and Client tables). Next, the company will be allowed to assign certain clients to certain of it's employees (EmployeeClient table). Imagine an employee working on projects for a few clients for which s/he can write billable hours, but the employee must not be allowed to write billable hours for clients they are not assigned to by their employer (the company). So, employees will not automatically have access to all their company's clients, but only to those that the company has selected for them. Hopefully this has shed some more light on the matter.

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• Programming Language Choices for High Integrity Systems

  - by Finbarr

  What programming languages are a good choice for High Integrity Systems? An example of a bad choice is Java as there is a considerable amount of code that is inaccessible to the programmer. I am looking for examples of strongly typed, block structured languages where the programmer is responsible for 100% of the code, and there is as little interference from things like a JVM as possible. Compilers will obviously be an issue. Language must have a complete and unambiguous definition.

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• Should I trust Redis for data integrity?

  - by Jiaji

  In my current project, I have PostgreSQL as my master DB, and Redis as kind of a slave, e.g., when some user adds another as a friend, first the relationship will be stored in PostgreSQL and then a friend list in Redis will be updated. When some user's friend list is requested, it will be pulled out of Redis instead of PostgreSQL. The question is: when I update the friend list in Redis, should I get a fresh copy outof PostgreSQL, and replace the old list in Redis with the new one or should I keep the old list and simply SADD the userid into the list? The latter is of course best for performance, but intuitively the former does a better job in keep the data integrity? And if something like Celery is used, is the second method worth the risk?

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• "SQLSTATE[23000]: Integrity constraint violation" in Doctrine

  - by rags

  Hi, i do get an Integrity constraint violation for Doctrine though i really can't see why. Schema.yml User: columns: id: type: integer primary: true autoincrement: true username: type: varchar(64) notnull: true email: type: varchar(128) notnull: true password: type: varchar(128) notnull: true relations: Websites: class: Website local: id foreign: owner type: many foreignType: one onDelete: CASCADE Website: columns: id: type: integer primary: true autoincrement: true active: type: bool owner: type: integer notnull: true plz: type: integer notnull: true longitude: type: double(10,6) notnull: true latitude: type: double(10,6) notnull: true relations: Owner: type: one foreignType: many class: User local: owner foreign: id And here's my data Fixtures (data.yml) Model_User: User_1: username: as email: as****.com password: ***** Model_Website: Website_1: active: true plz: 34222 latitude: 13.12 longitude: 3.56 Owner: User_1

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• django forms from two tables referencial integrity

  - by dana

  i have a class named cv,and a class named university, and each user that completes his cv, should choose a University he studyes at. My problem is: one student can study at one or 2 or three universities, or may be a user that is not student. I need to take this data into a form, and i use ModelForm. The data from the Cv class, and from the University class in the same form, and the user can add one or more universities, or no university. (in the same form) How should i do it? Should i use ModelForm? if i have a foreign key in the CV class, and the user is not a student (so he is at zero universities), i may get an referencial integrity error. thanks a lot

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• Sharepoint: Integrity of lookup fields after a list import

  - by driAn

  Hi there I got a question about the behavior of lookup fields when importing data. I wonder how the lookup fields behave when the list they point to is being replaced/imported. To explain the issue, I will provide a quick example below: As example, assume we have these two sharepoint lists: Product Types ------------- + Type Name + Code Nr + etc Products -------- + Product Name + Product Type (Lookup field to list "Product Types") + etc In my scenario, the Products List contains production data on the production Sharepoint platform. It is filled with data by the business users. However the Product Types list contains rather static data and is maintained by the developer. Now after a development cycle, the developer wants to deploy his new webparts and his new data (product types list). The developer performs the following procedure: On the dev machine: Export "product type" list using stsadm On the production machine: Delete all items in the "product type" list On the production machine: Import the "product type" list using stsadm This means we basically replace the "product type" list on the production server while keeping the "product" list as it is. Now the question: Is this safe? Will the lookup references break under certain circumstances? Any downside of this import/export procedure? What happens if someone accesses a "product" during the import? Will the (now invalid) reference clear its own content (become a null value). What happens if the schema of the "product type" list changes (new column)? Will this cause any troubles? Thanks for all feedback and suggestions!

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• Maintaining integrity of Core Data Entities with many incoming one-to-many relationships

  - by Henry Cooke

  Hi all. I have a Core Data store which contains a number of MediaItem entities that describe, well, media items. I also have NewsItems, which have one-to-many relationships to a number of MediaItems. So far so good. However, I also have PlayerItems and GalleryItems which also have one-to-many relationships to MediaItems. So MediaItems are shared across entities. Given that many entities may have one-to-many relationships, how can I set up reciprocal relationships from a MediaItem to all (1 or more) of the entities which have relationships to it and, furthermore, how can I implement rules to delete MediaItems when the number of those reciprocal relationships drops to 0?

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• Hibernate database integrity with multiple java applications

  - by Austen

  We have 2 java web apps both are read/write and 3 standalone java read/write applications (one loads questions via email, one processes an xml feed, one sends email to subscribers) all use hibernate and share a common code base. The problem we have recently come across is that questions loaded via email sometimes overwrite questions created in one of the web apps. We originally thought this to be a caching issue. We've tried turning off the second level cache, but this doesn't make a difference. We are not explicitly opening and closing sessions, but rather let hibernate manage them via Util.getSessionFactory().getCurrentSession(), which thinking about it, may actually be the issue. We'd rather not setup a clustered 2nd level cache at this stage as this creates another layer of complexity and we're more than happy with the level of performance we get from the app as a whole. So does implementing a open-session-in-view pattern in the web apps and manually managing the sessions in the standalone apps sound like it would fix this? Or any other suggestions/ideas please? <property name="hibernate.transaction.factory_class">org.hibernate.transaction.JDBCTransactionFactory</property> <property name="hibernate.current_session_context_class">thread</property> <property name="hibernate.cache.use_second_level_cache">false</property>

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• Coverity Rolls Out 'Software Integrity' Program

  Provides an objective standard to measure the integrity of software and reveal defects in third-party software Coverity - Business - Industry-Specific - Technology - Software for Engineering

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• How to organize integrity tests and code unit tests?

  - by karlthorwald

  I have several files with code testing code (which uses a "unittest" class). Later I found it would be nice to test database integrity also. I put this into a separate directory tree. (Things like the keys have correct format, parent and child nodes are pointing correctly and such.) I use the same unittest class for the integrity tests. Now I wonder if it makes really sense to keep this separate. To test the integrity of data I often duplicate parts of code that I use to test the code that handles the data. But it is not the same. The code tests use test databases (that get deleted after each test) and the integrity tests connect to the live data and analyze it. The integrity tests I want to call from cron and send an alarm if something happens in the live database. How would you handle that? Are there standards for such a setup? What is your experience? My tendency is to put everything in the same file, which would result in the code tests also being executed by the cron on the production environment.

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• How to organize live data integrity tests and code unit tests?

  - by karlthorwald

  I have several files with code testing code (which uses a "unittest" class). Later I found it would be nice to test database integrity also. I put this into a separate directory tree. (Things like the keys have correct format, parent and child nodes are pointing correctly and such.) I use the same unittest class for the integrity tests. Now I wonder if it makes really sense to keep this separate. To test the integrity of data I often duplicate parts of code that I use to test the code that handles the data. But it is not the same. The code tests use test databases (that get deleted after each test) and the integrity tests connect to the live data and analyze it. The integrity tests I want to call from cron and send an alarm if something happens in the live database. How would you handle that? Are there standards for such a setup? What is your experience? My tendency is to put everything in the same file, which would result in the code tests also being executed by the cron on the production environment.

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• Prevent two users from editing the same data

  - by Industrial

  Hi everyone, I have seen a feature in different web applications including Wordpress (not sure?) that warns a user if he/she opens an article/post/page/whatever from the database, while someone else is editing the same data simultaneously. I would like to implement the same feature in my own application and I have given this a bit of thought. Is the following example a good practice on how to do this? It goes a little something like this: 1) User A enters a the editing page for the mysterious article X. The database tableEvents is queried to make sure that no one else is editing the same page for the moment, which no one is by then. A token is then randomly being generated and is inserted into a database table called Events. 1) User B also want's to make updates to the article X. Now since our User A already is editing the article, the Events table is queried and looks like this: | timestamp | owner | Origin | token | ------------------------------------------------------------ | 1273226321 | User A | article-x | uniqueid## | 2) The timestamp is being checked. If it's valid and less than say 100 seconds old, a message appears and the user cannot make any changes to the requested article X: Warning: User A is currently working with this article. In the meantime, editing cannot be done. Please do something else with your life. 3) If User A decides to go on and save his changes, the token is posted along with all other data to update the database, and toggles a query to delete the row with token uniqueid##. If he decides to do something else instead of committing his changes, the article X will still be available for editing in 100 seconds for User B Let me know what you think about this approach! Wish everyone a great weekend!

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• Introduction to Lean Software Development and Kanban Systems – Build Integrity and Quality In

  - by Ben Griswold

  In this post, we’ll continue the series by concentrating on Principle #3: Build Integrity and Quality In.   In the next part of the series, we’ll dive into Principle #4: Defer Commitment and Decide As Late As Possible. And I am going to be a little obnoxious about listing my Lean and Kanban references with every series post.  The references are great and they deserve this sort of attention.  

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• Referential Integrity: Best Practices for IBM DB2

  Of the various constraints possible on relational tables, referential constraints are perhaps the most common ... and most misused. Learn about the advantages and disadvantages of different methods to implement and enforce RI, and issues that must be addressed when implementing DBMS-enforced Referential Integrity.

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• Sets, Surrogates, Normalisation, Referential Integrity - the Theory with example Scaling considerati

  - by tonyrogerson

  The Slides and Demo's for the SQLBits session I did today at SQL Bits in London are attached. The Agenda was... Thinking in Sets Surrogate Keys ú What they are ú Comparison NEWID, NEWSEQUENTIALID, IDENTITY ú Fragmenation Normalisation ú An introduction – what is it? Why use it? ú Joins – Pre-filter problems, index intersection ú Fragmentation again Referential Integrity ú Optimiser -> Query rewrite ú Locking considerations around Foreign Keys and Declarative RI (using Triggers)...(read more)

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• What hash should be used to ensure file integrity?

  - by Corey Ogburn

  It's no secret that large files offered up for download often are coupled with their MD5 or SHA-1 hash so that after you download you can verify the file's integrity. Are these still the best algorithms to use for this? Obviously these are very popular hashes that potential downloaders would have easy access to. Ignoring that factor, what hashes have the best properties for being used for this? For example, bcrypt would be horrible for this. It's designed to be slow. That would suck to use on your 7.4 GB dual layer OS ISO you just downloaded when a 12 letter password might take up to a second with the right parameters.

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• Is data integrity possible without normalization?

  - by shuniar

  I am working on an application that requires the storage of location information such as city, state, zip code, latitude, and longitude. I would like to ensure: Location data is accurate Detroit, CA Detroit IS NOT in California Detroit, MI Detroit IS in Michigan Cities and states are spelled correctly California not Calefornia Detroit not Detriot Cities and states are named consistently Valid: CA Detroit Invalid: Cali california DET d-town The D Also, since city/zip data is not guaranteed to be static, updating this data in a normalized fashion could be difficult, whereas it could be implemented as a de facto location if it is denormalized. A couple thoughts that come to mind: A collection of reference tables that store a list of all states and the most common cities and zip codes that can grow over time. It would search the database for an exact or similar match and recommend corrections. Use some sort of service to validate the location data before it is stored in the database. Is it possible to fulfill these requirements without normalization, and if so, should I denormalize this data?

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• PASS Data Architecture VC presents Neil Hambly on Improve Data Quality & Integrity using Constraints

  On Tuesday June 19th 12PM noon Central, Neil Hambly will discuss "Leveraging the power of constraints to improve both data quality and performance of your databases." What are your servers really trying to tell you? Find out with new SQL Monitor 3.0, an easy-to-use tool built for no-nonsense database professionals.For effortless insights into SQL Server, download a free trial today.

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• Multiplayer Game Listen Servers: Ensuring Integrity

  - by Ankit Soni

  I'm making a simple multiplayer game of Tic Tac Toe in Python using Bridge (its an RPC service built over a message queue - RabbitMQ) and I'd like to structure it so that the client and the server are just one file. When a user runs the game, he is offered a choice to either create a game or join an existing game. So when a user creates a game, the program will create the game and also join him as a player to the game. This is basically a listen server (as opposed to a dedicated server) - a familiar concept in multiplayer games. I came across a really interesting question while trying to make this - how can I ensure that the player hosting the game doesn't tamper with it (or atleast make it difficult)? The player hosting the game has access to the array used to store the board etc., and these must be stored in the process' virtual memory, so it seems like this is impossible. On the other hand, many multiplayer games use this model for LAN games.

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• HP Adds New Itanium to Integrity Server Line

  But the processor is only the beginning of the story, says HP, as it overhauls its high-end servers across the board.

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