Search Results

Search found 30822 results on 1233 pages for 'database replication'.

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

Page 28/1233 | < Previous Page | 24 25 26 27 28 29 30 31 32 33 34 35  | Next Page >

  • Database Modelling - Conceptually different entities with near identical fields

    - by Andrew Shepherd
    Suppose you have two sets of conceptual entities: MarketPriceDataSet which has multiple ForwardPriceEntries PoolPriceForecastDataSet which has multiple PoolPriceForecastEntry Both different child objects have near identical fields: ForwardPriceEntry has StartDate EndDate SimulationItemId ForwardPrice MarketPriceDataSetId (foreign key to parent table) PoolPriceForecastEntry has StartDate EndDate SimulationItemId ForecastPoolPrice PoolPriceForecastDataSetId (foreign key to parent table) If I modelled them as separate tables, the only difference would be the foreign key, and the name of the price field. There has been a debate as to whether the two near identical tables should be merged into one. Options I've thought of to model this is: Just keep them as two independent, separate tables Have both sets in the one table with an additional "type" field, and a parent_id equalling a foreign key to either parent table. This would sacrifice referential integrity checks. Have both sets in the one table with an additional "type" field, and create a complicated sequence of joining tables to maintain referential integrity. What do you think I should do, and why?

    Read the article

  • Database design - table relationship question

    - by iama
    I am designing schema for a simple quiz application. It has 2 tables - "Question" and "Answer Choices". Question table has 'question ID', 'question text' and 'answer id' columns. "Answer Choices" table has 'question ID', 'answer ID' and 'answer text' columns. With this simple schema it is obvious that a question can have multiple answer choices & hence the need for the answer choices table. However, a question can have only one correct answer and hence the need for the 'answer ID' in the question table. However, this 'answer ID' column in the question table provides a illusion as though there can be multiple questions for a single answer which is not correct. The other alternative to eliminate this illusion is to have another table just for correct answer that will have just 2 columns namely the question ID and the answer ID with a 1-1 relationship between the two tables. However, I think this is redundant. Any recommendation on how best to design this thereby enforcing the rules that a question can have multiple answer choices but only one correct answer? Many Thanks.

    Read the article

  • Generic version control strategy for select table data within a heavily normalized database

    - by leppie
    Hi Sorry for the long winded title, but the requirement/problem is rather specific. With reference to the following sample (but very simplified) structure (in psuedo SQL), I hope to explain it a bit better. TABLE StructureName { Id GUID PK, Name varchar(50) NOT NULL } TABLE Structure { Id GUID PK, ParentId GUID (FK to Structure), NameId GUID (FK to StructureName) NOT NULL } TABLE Something { Id GUID PK, RootStructureId GUID (FK to Structure) NOT NULL } As one can see, Structure is a simple tree structure (not worried about ordering of children for the problem). StructureName is a simplification of a translation system. Finally 'Something' is simply something referencing the tree's root structure. This is just one of many tables that need to be versioned, but this one serves as a good example for most cases. There is a requirement to version to any changes to the name and/or the tree 'layout' of the Structure table. Previous versions should always be available. There seems to be a few possibilities to tackle this issue, like copying the entire structure, but most approaches causes one to 'loose' referential integrity. Example if one followed this approach, one would have to make a duplicate of the 'Something' record, given that the root structure will be a new record, and have a new ID. Other avenues of possible solutions are looking into how Wiki's handle this or go a lot further and look how proper version control systems work. Currently, I feel a bit clueless how to proceed on this in a generic way. Any ideas will be greatly appreciated. Thanks leppie

    Read the article

  • Naming of boolean column in database table

    - by Space Cracker
    I have 'Service' table and the following column description as below Is User Verification Required for service ? Is User's Email Activation Required for the service ? Is User's Mobile Activation required for the service ? I Hesitate in naming these columns as below IsVerificationRequired IsEmailActivationRequired IsMobileActivationRequired or RequireVerification RequireEmailActivation RequireMobileActivation I can't determined which way is the best .So, Is one of the above suggested name is the best or is there other better ones ?

    Read the article

  • Upgrading from SQL2000 database to SQL Express 2008 R2

    - by itwb
    Hi, We have a web application which uses a MSSQL 2000 backend database. We are currently paying a ridiculous amount for Shared Hosting, with the database costs alone costing us $150 per month (MSSQL 100mb extra space is $40 per month). Our database size is 896.38 MB I am looking at getting a Virtual Private Server and upgrading the database to a MSSQL2008 Express database. I am aware that the Express version is limited to a 10GB database (with R2), and is constrained to a single CPU. I have also been offered SQL Server 2008 Web Edition for $19/per month, but I cannot find many details on the difference between Express and Web. Any suggestions here? What I would also like to know is: If we upgrade the database to MSSQL 2008 database, is there any issues with possible data transformations in the future? I.e. Is it possible to download and mount it with SQL Server 2008 Standard edition? I'm more concerned about how to get data in and out of the database through SQL Management tools. Are there any other issues that I might face? Thanks, Mike

    Read the article

  • MySQL root user can't access database

    - by Ed Schofield
    Hi all, We have a MySQL database ('myhours') on a production database server that is accessible to one user ('edsf') only, but not to the root user. The command 'SHOW DATABASES' as the root user does not list the 'myhours' database. The same command as the 'edsf' user lists the database: mysql> SHOW DATABASES; +--------------------+ | Database | +--------------------+ | information_schema | | myhours | +--------------------+ 2 rows in set (0.01 sec) Only the 'edsf' user can access the 'myhours' database with 'USE myhours'. Neither user seems to have permission to grant further permissions for this database. My questions are: Q1. How is it that the root user does not have permission to use the database? How could this have come about? The output of SHOW GRANTS FOR 'root'@'localhost'; looks fine to me: GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' IDENTIFIED BY PASSWORD '*xxx' WITH GRANT OPTION Q2. How can I recover this situation to make this database visible to the MySQL root user and grant further permissions on it? Thanks in advance for any help! -- Ed

    Read the article

  • Getting started with Oracle Database In-Memory Part III - Querying The IM Column Store

    - by Maria Colgan
    In my previous blog posts, I described how to install, enable, and populate the In-Memory column store (IM column store). This weeks post focuses on how data is accessed within the IM column store. Let’s take a simple query “What is the most expensive air-mail order we have received to date?” SELECT Max(lo_ordtotalprice) most_expensive_order FROM lineorderWHERE  lo_shipmode = 5; The LINEORDER table has been populated into the IM column store and since we have no alternative access paths (indexes or views) the execution plan for this query is a full table scan of the LINEORDER table. You will notice that the execution plan has a new set of keywords “IN MEMORY" in the access method description in the Operation column. These keywords indicate that the LINEORDER table has been marked for INMEMORY and we may use the IM column store in this query. What do I mean by “may use”? There are a small number of cases were we won’t use the IM column store even though the object has been marked INMEMORY. This is similar to how the keyword STORAGE is used on Exadata environments. You can confirm that the IM column store was actually used by examining the session level statistics, but more on that later. For now let's focus on how the data is accessed in the IM column store and why it’s faster to access the data in the new column format, for analytical queries, rather than the buffer cache. There are four main reasons why accessing the data in the IM column store is more efficient. 1. Access only the column data needed The IM column store only has to scan two columns – lo_shipmode and lo_ordtotalprice – to execute this query while the traditional row store or buffer cache has to scan all of the columns in each row of the LINEORDER table until it reaches both the lo_shipmode and the lo_ordtotalprice column. 2. Scan and filter data in it's compressed format When data is populated into the IM column it is automatically compressed using a new set of compression algorithms that allow WHERE clause predicates to be applied against the compressed formats. This means the volume of data scanned in the IM column store for our query will be far less than the same query in the buffer cache where it will scan the data in its uncompressed form, which could be 20X larger. 3. Prune out any unnecessary data within each column The fastest read you can execute is the read you don’t do. In the IM column store a further reduction in the amount of data accessed is possible due to the In-Memory Storage Indexes(IM storage indexes) that are automatically created and maintained on each of the columns in the IM column store. IM storage indexes allow data pruning to occur based on the filter predicates supplied in a SQL statement. An IM storage index keeps track of minimum and maximum values for each column in each of the In-Memory Compression Unit (IMCU). In our query the WHERE clause predicate is on the lo_shipmode column. The IM storage index on the lo_shipdate column is examined to determine if our specified column value 5 exist in any IMCU by comparing the value 5 to the minimum and maximum values maintained in the Storage Index. If the value 5 is outside the minimum and maximum range for an IMCU, the scan of that IMCU is avoided. For the IMCUs where the value 5 does fall within the min, max range, an additional level of data pruning is possible via the metadata dictionary created when dictionary-based compression is used on IMCU. The dictionary contains a list of the unique column values within the IMCU. Since we have an equality predicate we can easily determine if 5 is one of the distinct column values or not. The combination of the IM storage index and dictionary based pruning, enables us to only scan the necessary IMCUs. 4. Use SIMD to apply filter predicates For the IMCU that need to be scanned Oracle takes advantage of SIMD vector processing (Single Instruction processing Multiple Data values). Instead of evaluating each entry in the column one at a time, SIMD vector processing allows a set of column values to be evaluated together in a single CPU instruction. The column format used in the IM column store has been specifically designed to maximize the number of column entries that can be loaded into the vector registers on the CPU and evaluated in a single CPU instruction. SIMD vector processing enables the Oracle Database In-Memory to scan billion of rows per second per core versus the millions of rows per second per core scan rate that can be achieved in the buffer cache. I mentioned earlier in this post that in order to confirm the IM column store was used; we need to examine the session level statistics. You can monitor the session level statistics by querying the performance views v$mystat and v$statname. All of the statistics related to the In-Memory Column Store begin with IM. You can see the full list of these statistics by typing: display_name format a30 SELECT display_name FROM v$statname WHERE  display_name LIKE 'IM%'; If we check the session statistics after we execute our query the results would be as follow; SELECT Max(lo_ordtotalprice) most_expensive_order FROM lineorderWHERE lo_shipmode = 5; SELECT display_name FROM v$statname WHERE  display_name IN ('IM scan CUs columns accessed',                        'IM scan segments minmax eligible',                        'IM scan CUs pruned'); As you can see, only 2 IMCUs were accessed during the scan as the majority of the IMCUs (44) in the LINEORDER table were pruned out thanks to the storage index on the lo_shipmode column. In next weeks post I will describe how you can control which queries use the IM column store and which don't. +Maria Colgan

    Read the article

  • Oracle GoldenGate 12c - Leading Enterprise Replication

    - by Doug Reid
    Oracle GoldenGate 12c released  on October 17th and includes several new cutting edge features that firmly establishes GoldenGate's leader position in the data replication space.   In fact, this release more than doubles the performance of data delivery, supports Oracle's new multitenant database feature,  it's more secure, has more options for high availability, and has made great strides to simplify the configuration and deployment of the product.     Read through the press release if you haven't already and do not miss the quote from Cern's Eva Dafonte Perez, regarding Oracle GoldenGate 12c "….performs five times faster compared to previous GoldenGate versions and simplifies the management of a multi-tier environment" There are a variety of new and improved features in the Oracle GoldenGate 12c.  Here are the highlights: Optimized for Oracle Database 12c -  GoldenGate 12c is custom tailored to the unique capabilities of Oracle database 12c and out of the box GoldenGate 12c supports multitenant (pluggable database (PDB)) and non-consolidated deployments of Oracle Database 12c.   The naming convention used by database 12c is now in three parts (PDB-name, schema-name, and object name).  We have made changes to the GoldenGate capture process to support the new naming convention and streamlined the whole process so a single GoldenGate capture process is being used at the container level rather than at each individual PDB.  By having the capture process at the container level resource usage and the number of processes are reduced. To view a conceptual architecture diagram click here. Integrated Delivery for the Oracle Database - Leveraging a lightweight streaming API built exclusively for Oracle GoldenGate 12c, this process distributes load, auto tunes the degree of parallelism, scales better, and delivers blinding rates of changed data delivery to the Oracle database.  One of the goals for Oracle GoldenGate 12c was to reduce IT costs by simplifying the configuration and reduce the time to manage complex infrastructures.  In previous versions of Oracle GoldenGate, customers would split transaction loads by grouping tables into multiple different delivery processes (click here to view the previous method). Each delivery process executed independently and without any interaction or knowledge of other delivery processes.  This setup was complicated to configure and time consuming as the developer needed in-depth knowledge of the source and target schemas and the transaction profile. With GoldenGate 12c and Integrated Delivery we have made it easier to configure and faster to deploy.  To view a conceptual architecture diagram of integrated delivery click here Coordinated Delivery for Non-Oracle Databases - Coordinated Delivery orchestrates high-speed apply processes and simplifies the configuration of GoldenGate for non-Oracle targets. In Oracle GoldenGate 12c a single delivery process is used with multiple threads (click here) and key events, such as primary key updates, event markers, DDL, etc, are coordinated between the various threads to insure that the transactions are applied in the same sequence as they were captured, all while delivery improved performance.  Replication Between On-Premises and Cloud-Based systems. - The trend for business to utilize both on-premises and cloud-based systems is rising and businesses need to replicate data back and forth.   GoldenGate 12c can be configured in a variety of ways to provide real-time replication when unrestricted or restricted (limited ports or HTTP tunneling) networks are between on-premises and cloud-based systems.    Expanded Heterogeneity - It wouldn't be a GoldenGate release without new and improved platform support.   Release 1 includes support for MySQL 5.6 and Sybase 15.7.   Upcoming in the next release GoldenGate, support will be expanded for MS SQL Server, DB2, and Teradata. Tighter Security - Oracle GoldenGate 12c is integrated with the Oracle wallet to shield usernames and passwords using strong encryption and aliases.   Customers accustomed to using the Oracle Wallet with other Oracle products will instantly be familiar with how to use this great new feature Expanded Oracle Application and Technology Support -   GoldenGate can be used along with Oracle Coherence to enable real-time changed data feeds to the Coherence cache using Toplink and the Oracle GoldenGate JMS adapter.     Plus,  Oracle Advanced Customer Services (ACS) now offers a low downtime E-Business Suite platform and database migrations using GoldenGate as the enabling technology.  Keep tuned for more blogs on the new features and the upcoming launch webcast where we will go into these new features in more detail.   In the mean time make sure to read through our white paper "Oracle GoldenGate 12c Release 1 New Features Overview"

    Read the article

  • Problems locating Redmine database

    - by zordor
    I have an active redmine but I can not find the database where it is running right now. It should be on PostgreSQL but the database where it should be running is empty. Does anybody have any idea how to check current database used by redmine? Please let me know if you need any extra information. Thank you EDIT: Ok I know the database it is using. On the database.yml I have project_redmine but it is using the database project I dont know why. That database it is used by developers for the actual project. So that is getting me problems of course. I am unable to run it on the right DB (project_redmine) any ideas? :S

    Read the article

  • Changing Recovery Model in Replicated Database

    - by Rob
    I now am the proud owner of two servers that replicate with each other. I had nothing to do with the install, but (of course), now i have to support the databases. Both databases are in the Simple recovery model, but the users want to ensure as little data loss as possible so I'm thinking that I should change the recovery model over to full and start doing transaction log backups. I wasn't planning on backing up the subscribing database, only the publisher. Is this the right plan? Do I need to switch both the Subscriber and and the publisher to Full, or can I leave the subscriber in Simple, but have the Publisher in Full? When I change the recovery model in one (or both) do the databases need to be offline? Thanks

    Read the article

  • Centrally managing 100+ websites without bankrupting a small company

    - by palintropos
    I'm mainly interested in opinions on the trade-offs between having a single central server all the websites connect to as opposed to each website mirroring a subset of the master database with all the products in it. For example, will I run into severe performance issues (or even security issues, or restrictions) making queries to an offsite database? Will we hit scalability issues we can't handle early on from the sheer bandwidth required to maintain this? If we do go with something like a script that keeps smaller databases (each containing a subset of the central master data) in sync, what sorts of issues will we likely encounter there? I would really like the opinions of people far more knowledgeable than I am regarding the pros and cons of both setups and what headaches we are likely to encounter. CLARIFICATION: This should not be viewed as a question about whether we should implement one database vs multiple databases. This question has been answered numerous times. The question is regarding the pros and cons for a deployment like this having the ability to manage all the websites centrally (one server) vs trying to keep them all in sync if they each have their own db (multiple servers). REAL-WORLD EXAMPLE: We are a t-shirt company, and we have individual websites for our different kinds of t-shirts, but we're looking at a central order management integrated with our single shopping cart (which is ColdFusion + MySQL). Now, let's say we have a t-shirt that's on 10 of our websites and we change an image for it. Ideally we would change that in one place and the change would propagate, but how would we set this up?

    Read the article

  • Relational vs. Dimensional Databases, what's the difference?

    - by grautur
    I'm trying to learn about OLAP and data warehousing, and I'm confused about the difference between relational and dimensional modeling. Is dimensional modeling basically relational modeling, but allowing for redundant/un-normalized data? For example, let's say I have historical sales data on (product, city, # sales). I understand that the following would be a relational point-of-view: Product | City | # Sales Apples, San Francisco, 400 Apples, Boston, 700 Apples, Seattle, 600 Oranges, San Francisco, 550 Oranges, Boston, 500 Oranges, Seattle, 600 While the following is a more dimensional point-of-view: Product | San Francisco | Boston | Seattle Apples, 400, 700, 600 Oranges, 550, 500, 600 But it seems like both points of view would nonetheless be implemented in an identical star schema: Fact table: Product ID, Region ID, # Sales Product dimension: Product ID, Product Name City dimension: City ID, City Name And it's not until you start adding some additional details to each dimension that the differences start popping up. For instance, if you wanted to track regions as well, a relational database would tend to have a separate region table, in order to keep everything normalized: City dimension: City ID, City Name, Region ID Region dimension: Region ID, Region Name, Region Manager, # Regional Stores While a dimensional database would allow for denormalization to keep the region data inside the city dimension, in order to make it easier to slice the data: City dimension: City ID, City Name, Region Name, Region Manager, # Regional Stores Is this correct?

    Read the article

  • NoSQL for filesystem storage organization and replication?

    - by wheaties
    We've been discussing design of a data warehouse strategy within our group for meeting testing, reproducibility, and data syncing requirements. One of the suggested ideas is to adapt a NoSQL approach using an existing tool rather than try to re-implement a whole lot of the same on a file system. I don't know if a NoSQL approach is even the best approach to what we're trying to accomplish but perhaps if I describe what we need/want you all can help. Most of our files are large, 50+ Gig in size, held in a proprietary, third-party format. We need to be able to access each file by a name/date/source/time/artifact combination. Essentially a key-value pair style look-up. When we query for a file, we don't want to have to load all of it into memory. They're really too large and would swamp our server. We want to be able to somehow get a reference to the file and then use a proprietary, third-party API to ingest portions of it. We want to easily add, remove, and export files from storage. We'd like to set up automatic file replication between two servers (we can write a script for this.) That is, sync the contents of one server with another. We don't need a distributed system where it only appears as if we have one server. We'd like complete replication. We also have other smaller files that have a tree type relationship with the Big files. One file's content will point to the next and so on, and so on. It's not a "spoked wheel," it's a full blown tree. We'd prefer a Python, C or C++ API to work with a system like this but most of us are experienced with a variety of languages. We don't mind as long as it works, gets the job done, and saves us time. What you think? Is there something out there like this?

    Read the article

  • Still Confused About Identifying vs. Non-Identifying Relationships

    - by Jason
    So, I've been reading up on identifying vs. non-identifying relationships in my database design, and a number of the answers on SO seem contradicting to me. Here are the two questions I am looking at: What's the Difference Between Identifying and Non-Identifying Relationships Trouble Deciding on Identifying or Non-Identifying Relationship Looking at the top answers from each question, I appear to get two different ideas of what an identifying relationship is. The first question's response says that an identifying relationship "describes a situation in which the existence of a row in the child table depends on a row in the parent table." An example of this that is given is, "An author can write many books (1-to-n relationship), but a book cannot exist without an author." That makes sense to me. However, when I read the response to question two, I get confused as it says, "if a child identifies its parent, it is an identifying relationship." The answer then goes on to give examples such as SSN (is identifying of a Person), but an address is not (because many people can live at an address). To me, this sounds more like a case of the decision between primary key and non-primary key. My own gut feeling (and additional research on other sites) points to the first question and its response being correct. However, I wanted to verify before I continued forward as I don't want to learn something wrong as I am working to understand database design. Thanks in advance.

    Read the article

  • How do you decide what kind of database to use?

    - by Jason Baker
    I really dislike the name "NoSQL", because it isn't very descriptive. It tells me what the databases aren't where I'm more interested in what the databases are. I really think that this category really encompasses several categories of database. I'm just trying to get a general idea of what job each particular database is the best tool for. A few assumptions I'd like to make (and would ask you to make): Assume that you have the capability to hire any number of brilliant engineers who are equally experienced with every database technology that has ever existed. Assume you have the technical infrastructure to support any given database (including available servers and sysadmins who can support said database). Assume that each database has the best support possible for free. Assume you have 100% buy-in from management. Assume you have an infinite amount of money to throw at the problem. Now, I realize that the above assumptions eliminate a lot of valid considerations that are involved in choosing a database, but my focus is on figuring out what database is best for the job on a purely technical level. So, given the above assumptions, the question is: what jobs are each database (including both SQL and NoSQL) the best tool for and why?

    Read the article

  • any practices ,samples for ERD?

    - by just_name
    Q: I wanna any web sites , any books just for training on ERD and normalization ,, i wanna a lot of samples ,practices,and case studies with recommended answers, to strength myself in database design.and avoid the poor data base design i made . note:i don't need books to explain the concepts , what i need is practices ,examples,case studies with recommended answers. Thanks in advance.

    Read the article

  • What are possible results/side effects if replication between DC's in a Windows domain is unable to occur?

    - by hydroparadise
    There's plenty of administration literature out there how to properly manage Windows servers. But in dealing with real life, things don't always occur like you want them to. In Microsoft's Windows Server 2003 Administrator's Companion, out of 1400+ pages, theres only one page that I could find when it comes up setting up additional domain controlers. They make it sound seemless and don't reveal a whole lot on what happens if "peer" DC's are unable to replicate. Down to the specific issue at hand, we had a DC go down about a month ago due to a bad RAID controller. There was nothing critical that waranted imediate attention, so bringing it back up got put on the back burner. A month later, we get the DC back up and running and everyting seemed ok. The next day, nobody is able to logon complaining that the "user does not exist" or "unable to establish a trust relationship". Knowing that I had just put the downed DC back on the network, I immediately took it back off the network and had everybody restart the workstations. After that, exchange was fine, shares became available, and everybody was able to log in. After doing some event log swimming, it would appear that everything started due to replication issues on the SYSVOL. I've read where you can force replication, but that would mean putting it back on the network. I am afraid to put the DC back on the network in fear that something else could go wrong. So, what other issues could one expect to run into where two DC's are unreplicated for over a month?

    Read the article

  • Android threading and database locking

    - by Sena Gbeckor-Kove
    Hi, We are using AsyncTasks to access database tables and cursors. Unfortunately we are seeing occasional exceptions regarding the database being locked. E/SQLiteOpenHelper(15963): Couldn't open iviewnews.db for writing (will try read-only): E/SQLiteOpenHelper(15963): android.database.sqlite.SQLiteException: database is locked E/SQLiteOpenHelper(15963): at android.database.sqlite.SQLiteDatabase.native_setLocale(Native Method) E/SQLiteOpenHelper(15963): at android.database.sqlite.SQLiteDatabase.setLocale(SQLiteDatabase.java:1637) E/SQLiteOpenHelper(15963): at android.database.sqlite.SQLiteDatabase.<init>(SQLiteDatabase.java:1587) E/SQLiteOpenHelper(15963): at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:638) E/SQLiteOpenHelper(15963): at android.database.sqlite.SQLiteDatabase.openOrCreateDatabase(SQLiteDatabase.java:659) E/SQLiteOpenHelper(15963): at android.database.sqlite.SQLiteDatabase.openOrCreateDatabase(SQLiteDatabase.java:652) E/SQLiteOpenHelper(15963): at android.app.ApplicationContext.openOrCreateDatabase(ApplicationContext.java:482) E/SQLiteOpenHelper(15963): at android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:193) E/SQLiteOpenHelper(15963): at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:98) E/SQLiteOpenHelper(15963): at android.database.sqlite.SQLiteOpenHelper.getReadableDatabase(SQLiteOpenHelper.java:158) E/SQLiteOpenHelper(15963): at com.iview.android.widget.IViewNewsTopStoryWidget.initData(IViewNewsTopStoryWidget.java:73) E/SQLiteOpenHelper(15963): at com.iview.android.widget.IViewNewsTopStoryWidget.updateNewsWidgets(IViewNewsTopStoryWidget.java:121) E/SQLiteOpenHelper(15963): at com.iview.android.async.GetNewsTask.doInBackground(GetNewsTask.java:338) E/SQLiteOpenHelper(15963): at com.iview.android.async.GetNewsTask.doInBackground(GetNewsTask.java:1) E/SQLiteOpenHelper(15963): at android.os.AsyncTask$2.call(AsyncTask.java:185) E/SQLiteOpenHelper(15963): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:256) E/SQLiteOpenHelper(15963): at java.util.concurrent.FutureTask.run(FutureTask.java:122) E/SQLiteOpenHelper(15963): at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:648) E/SQLiteOpenHelper(15963): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:673) E/SQLiteOpenHelper(15963): at java.lang.Thread.run(Thread.java:1060) Does anybody have a general example for code which writes to a database from a different thread than the one reading and how can we ensure thread safety. One suggestion I've had is to use a ContentProvider, as this would handle the access of the database from multiple threads. I am going to look at this, but is this the recommended method of handling such a problem? It seems rather heavyweight considering we're talking about in front or behind Thanks in advance.

    Read the article

  • Enable Automatic Code First Migrations On SQL Database in Azure Web Sites

    - by Steve Michelotti
    Now that Azure supports .NET Framework 4.5, you can use all the latest and greatest available features. A common scenario is to be able to use Entity Framework Code First Migrations with a SQL Database in Azure. Prior to Code First Migrations, Entity Framework provided database initializers. While convenient for demos and prototypes, database initializers weren’t useful for much beyond that because, if you delete and re-create your entire database when the schema changes, you lose all of your operational data. This is the void that Migrations are meant to fill. For example, if you add a column to your model, Migrations will alter the database to add the column rather than blowing away the entire database and re-creating it from scratch. Azure is becoming increasingly easier to use – especially with features like Azure Web Sites. Being able to use Entity Framework Migrations in Azure makes deployment easier than ever. In this blog post, I’ll walk through enabling Automatic Code First Migrations on Azure. I’ll use the Simple Membership provider for my example. First, we’ll create a new Azure Web site called “migrationstest” including creating a new SQL Database along with it:   Next we’ll go to the web site and download the publish profile:   In the meantime, we’ve created a new MVC 4 website in Visual Studio 2012 using the “Internet Application” template. This template is automatically configured to use the Simple Membership provider. We’ll do our initial Publish to Azure by right-clicking our project and selecting “Publish…”. From the “Publish Web” dialog, we’ll import the publish profile that we downloaded in the previous step:   Once the site is published, we’ll just click the “Register” link from the default site. Since the AccountController is decorated with the [InitializeSimpleMembership] attribute, the initializer will be called and the initial database is created.   We can verify this by connecting to our SQL Database on Azure with SQL Management Studio (after making sure that our local IP address is added to the list of Allowed IP Addresses in Azure): One interesting note is that these tables got created with the default Entity Framework initializer – which is to create the database if it doesn’t already exist. However, our database did already exist! This is because there is a new feature of Entity Framework 5 where Code First will add tables to an existing database as long as the target database doesn’t contain any of the tables from the model. At this point, it’s time to enable Migrations. We’ll open the Package Manger Console and execute the command: PM> Enable-Migrations -EnableAutomaticMigrations This will enable automatic migrations for our project. Because we used the "-EnableAutomaticMigrations” switch, it will create our Configuration class with a constructor that sets the AutomaticMigrationsEnabled property set to true: 1: public Configuration() 2: { 3: AutomaticMigrationsEnabled = true; 4: } We’ll now add our initial migration: PM> Add-Migration Initial This will create a migration class call “Initial” that contains the entire model. But we need to remove all of this code because our database already exists so we are just left with empty Up() and Down() methods. 1: public partial class Initial : DbMigration 2: { 3: public override void Up() 4: { 5: } 6: 7: public override void Down() 8: { 9: } 10: } If we don’t remove this code, we’ll get an exception the first time we attempt to run migrations that tells us: “There is already an object named 'UserProfile' in the database”. This blog post by Julie Lerman fully describes this scenario (i.e., enabling migrations on an existing database). Our next step is to add the Entity Framework initializer that will automatically use Migrations to update the database to the latest version. We will add these 2 lines of code to the Application_Start of the Global.asax: 1: Database.SetInitializer(new MigrateDatabaseToLatestVersion<UsersContext, Configuration>()); 2: new UsersContext().Database.Initialize(false); Note the Initialize() call will force the initializer to run if it has not been run before. At this point, we can publish again to make sure everything is still working as we are expecting. This time we’re going to specify in our publish profile that Code First Migrations should be executed:   Once we have re-published we can once again navigate to the Register page. At this point the database has not been changed but Migrations is now enabled on our SQL Database in Azure. We can now customize our model. Let’s add 2 new properties to the UserProfile class – Email and DateOfBirth: 1: [Table("UserProfile")] 2: public class UserProfile 3: { 4: [Key] 5: [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)] 6: public int UserId { get; set; } 7: public string UserName { get; set; } 8: public string Email { get; set; } 9: public DateTime DateOfBirth { get; set; } 10: } At this point all we need to do is simply re-publish. We’ll once again navigate to the Registration page and, because we had Automatic Migrations enabled, the database has been altered (*not* recreated) to add our 2 new columns. We can verify this by once again looking at SQL Management Studio:   Automatic Migrations provide a quick and easy way to keep your database in sync with your model without the worry of having to re-create your entire database and lose data. With Azure Web Sites you can set up automatic deployment with Git or TFS and automate the entire process to make it dead simple.

    Read the article

  • Database version control resources

    - by Wes McClure
    In the process of creating my own DB VCS tool tsqlmigrations.codeplex.com I ran into several good resources to help guide me along the way in reviewing existing offerings and in concepts that would be needed in a good DB VCS.  This is my list of helpful links that others can use to understand some of the concepts and some of the tools in existence.  In the next few posts I will try to explain how I used these to create TSqlMigrations.   Blogs entries Three rules for database work - K. Scott Allen http://odetocode.com/blogs/scott/archive/2008/01/30/three-rules-for-database-work.aspx Versioning databases - the baseline http://odetocode.com/blogs/scott/archive/2008/01/31/versioning-databases-the-baseline.aspx Versioning databases - change scripts http://odetocode.com/blogs/scott/archive/2008/02/02/versioning-databases-change-scripts.aspx Versioning databases - views, stored procedures and the like http://odetocode.com/blogs/scott/archive/2008/02/02/versioning-databases-views-stored-procedures-and-the-like.aspx Versioning databases - branching and merging http://odetocode.com/blogs/scott/archive/2008/02/03/versioning-databases-branching-and-merging.aspx Evolutionary Database Design - Martin Fowler http://martinfowler.com/articles/evodb.html Are database migration frameworks worth the effort? - Good challenges http://www.ridgway.co.za/archive/2009/01/03/are-database-migration-frameworks-worth-the-effort.aspx Continuous Integration (in general) http://martinfowler.com/articles/continuousIntegration.html http://martinfowler.com/articles/originalContinuousIntegration.html Is Your Database Under Version Control? http://www.codinghorror.com/blog/archives/000743.html 11 Tools for Database Versioning http://secretgeek.net/dbcontrol.asp How to do database source control and builds http://mikehadlow.blogspot.com/2006/09/how-to-do-database-source-control-and.html .Net Database Migration Tool Roundup http://flux88.com/blog/net-database-migration-tool-roundup/ Books Book Description Refactoring Databases: Evolutionary Database Design Martin Fowler signature series on refactoring databases. Book site: http://databaserefactoring.com/ Recipes for Continuous Database Integration: Evolutionary Database Development (Digital Short Cut) A good question/answer layout of common problems and solutions with database version control. http://www.informit.com/store/product.aspx?isbn=032150206X

    Read the article

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

< Previous Page | 24 25 26 27 28 29 30 31 32 33 34 35  | Next Page >